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Jolle Kirpensteijn DVM, PhD, DipACVS, DipECVS and Gert ter Haar DVM, PhD, DipECVS, MRCVS Department of Clinical Sciences of Companion Animals Faculty of Veterinary Medicine University of Utrecht The Netherlands Manson Publishing/The Veterinary Press Reconstructive Surgery and Wound Management of the Dog and Cat Copyright © 2013 Manson Publishing Ltd ISBN: 978-1-84076-163-4 All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means without the written permission of the copyright holder or in accordance with the provisions of the Copyright Act 1956 (as amended), or under the terms of any licence permitting limited copying issued by the Copyright Licensing Agency, 33–34 Alfred Place, London WC1E 7DP, UK. Any person who does any unauthorized act in relation to this publication may be liable to criminal prosecution and civil claims for damages. A CIP catalogue record for this book is available from the British Library. For full details of all Manson Publishing Ltd titles please write to: Manson Publishing Ltd, 73 Corringham Road, London NW11 7DL, UK. Tel: +44(0)20 8905 5150 Fax: +44(0)20 8201 9233 Email: manson@mansonpublishing.com Website: www.mansonpublishing.com Commissioning editor: Jill Northcott Project manager: Kate Nardoni Copy editor: Peter Beynon Design: Cathy Martin Layout: diacriTech, India Colour reproduction: Tenon & Polert Colour Scanning Ltd, Hong Kong Printed by: Grafos SA, Barcelona, Spain www.mansonpublishing.com Contents Preface 5 Acknowledgements 5 Contributors 6 Foreword 7 Abbreviations 8 Chapter 1 Introduction 9 Gert ter Haar, Sjef C. Buiks, Marijn van Delden, Tjitte Reijntjes, Rick F. Sanchez and Jolle Kirpensteijn Anatomy 10 Blood supply 10 Skin tension 12 Tension-relieving suture patterns 13 Skin flaps and their classification 13 Reconstruction of the head 15 Eyelid reconstructive techniques 15 Reconstruction of the neck and trunk 17 Reconstruction of the forelimb 17 Reconstruction of the hindlimb 17 Wound closure techniques 18 Complications in performing plastic and reconstructive surgery 18 References 19 Chapter 2 Wound management: a new protocol for dogs and cats 21 Tosca van Hengel, Gert ter Haar and Jolle Kirpensteijn Introduction 22 Wound healing 22 Wound management 28 A protocol for wound management in dogs and cats 42 Cost-effectiveness and patient and owner benefit 43 Conclusion/summary 43 References 45 Chapter 3 General reconstructive techniques 49 Sjef C. Buiks, Marijn van Delden and Jolle Kirpensteijn Triangular lesion 50 Square lesion 51 Bow tie technique 52 Walking sutures 54 Releasing incisions 56 Mesh releasing incisions 58 Advancement (U-) flap 59 Double advancement or H-flap 62 V-Y plasty 64 Z-plasty 65 Reading man procedure 68 Transposition flap 70 Interpolation flap 72 Rotation flap 75 Chapter 4 Avascular and microvascular reconstructive techniques 77 Guido Camps and Jolle Kirpensteijn Introduction 78 Background to avascular and microvascular skin surgery 78 Avascular mesh graft 79 Microvascular flap transfer 82 Conclusion/summary 92 References 92 Chapter 5 Reconstructive techniques of the facial area and head 95 Sjef C. Buiks and Gert ter Haar Unilateral modified nasal rotation flap 96 Bilateral modified nasal rotation flap 98 Full-thickness labial advancement flap (lower lip) 100 4 Full-thickness labial advancement flap (upper lip) 102 Full-thickness buccal rotation flap 104 Transposition skin flap for upper labial and buccal replacement 106 Facial artery axial pattern flap 108 Superficial temporal artery axial pattern flap 110 Caudal auricular axial pattern flap 112 Pedicle flap for pinnal defects 114 Chapter 6 Reconstructive techniques of the eyelids 117 Rick F. Sanchez H-plasty 118 Z-plasty 121 Semicircular skin flap 126 Rhomboid flap 128 Modified cross lid flap 131 Lip-to-eye mucocutaneous subdermal plexus rotating flap 134 Superficial temporal artery axial pattern flap for reconstruction of the upper eyelid 139 Entropion repair and the arrowhead method for correction of lateral canthal entropion involving the upper and lower eyelid 144 Stades technique for correction of upper eyelid entropion/trichiasis 146 Munger–Carter flap adaptation of the Khunt–Szymanowski–Fox–Smith procedure for correction of lower eyelid ectropion and macroblepharon in dogs 149 Chapter 7 Reconstructive techniques of the neck and trunk 153 Marijn van Delden, Sjef C. Buiks and Gert ter Haar Omocervical axial pattern flap 154 Thoracodorsal axial pattern flap 156 Cranial superficial epigastric axial pattern flap 160 Cutaneous trunci myocutaneous flap 162 Latissimus dorsi myocutaneous flap 166 External abdominal oblique muscle flap 170 Tensor fascia lata flap 173 Episioplasty 176 Scrotal flap 178 Tail flap/lateral caudal axial pattern flap 180 Chapter 8 Reconstructive techniques of the forelimb 183 Sjef C. Buiks, Tjitte Reijntjes and Jolle Kirpensteijn Lateral thoracic artery axial pattern flap 184 Superficial brachial axial pattern flap 186 Axillary (forelimb) fold flap 189 Flexor carpi ulnaris muscle flap 193 Phalangeal fillet (digit I or dewclaw [P-I]) 196 Phalangeal fillet (digits II–IV) 200 Fusion podoplasty 204 Segmental pad transfer 207 Chapter 9 Reconstructive techniques of the hindlimb 209 Tjitte Reijntjes and Jolle Kirpensteijn Deep circumflex iliac axial pattern flap 210 Caudal superficial epigastric axial pattern flap 213 Flank fold flap 216 Genicular axial pattern flap 220 Cranial sartorius muscle flap 222 Caudal sartorius muscle flap 224 Reverse saphenous conduit flap 227 Metatarsal pad transfer 230 Index 233 5 in the treatment of animals with skin defects caused by injury or tumour resection. Why should one buy this book? If you are interested in skin surgery and you learn best by seeing a procedure performed, this atlas will show you all the procedures currently available in veterinary medicine and surgery using clear illustrations and step-by-step instructions. Consider it a cookbook with lots of ideas and recipes. A word of warning though – like cooking, surgery is a skill not mastered to the same degree by everyone. In addition, conditions are variable and do not remain constant. Use this book wisely, allow it to give you inspiration and evaluate each wound as an individual challenge to close. Every animal, and thus every wound, is different. This is why reconstructive surgery is so much fun! Jolle Kirpensteijn Gert ter Haar Preface The idea of designing a colour atlas of reconstructive techniques in dogs and cats started a couple of years ago during our lectures to residents in surgery. The plan was that the illustrations in the atlas would be comparable to the gold standard set by the excellent drawings in the books written by Michael Pavletic and Steven Swaim, with the additional advantage that they would demonstrate each reconstructive procedure step by step and using real tissues. In addition to being close personal friends, Michael and Steven have been immense sources of knowledge for this atlas. We would like to acknowledge and sincerely thank these two pioneers in reconstructive surgery for showing us the way to proceed, and we advise every reader to add their volumes to their library. The main goal of this atlas is to provide an overview of reconstructive techniques in dogs and cats, illustrated with high-quality pictures, as an aid Acknowledgements An atlas of this nature takes the input and hard work of a great number of people. We are indebted to many people for their assistance and support while writing this book. First, we sincerely thank our five students, Marijn van Delden, Sjef Buiks, Tjitte Reijntjes, Guido Camps and Tosca van Hengel, who were involved in the making of this atlas. As part of their training in scientific research, they dedicated three full months to studying the literature, bothveterinary and human, preparing the actual surgeries, and performing the surgeries under our close supervision. Without their enthusiasm, dedication, perseverance and logistical skills we would not have been able to write this book. Special thanks are in order for Joop Fama, who single-handedly took all the photographs in this atlas and did an outstanding job. It is unbelievable how many hours he spent on not only taking the photographs, but in processing and editing all the material afterwards. There would not have been an atlas if it had not been for Joop’s support. We owe thanks to Harry van Engelen and the veterinary technicians for providing all the materials we needed, even at short notice, and for cleaning up after us! We are very grateful for the contribution of Rick Sanchez. Without his eye for detail and concise knowledge of this specialist area, the quality of the eyelid reconstruction chapter would not have been so high. Thanks are due to Jill Northcott from Manson Publishing Limited for being very patient and believing in the end result while extending deadline after deadline. We thank Peter Beynon for performing an outstanding editing job, Bouvien Brocks for a final check and Kate Nardoni and Cathy Martin for making it even more beautiful than originally planned. It has been a pleasure working with them. 6 Contributors Sjef C. Buiks DVM Department of Clinical Sciences of Companion Animals Faculty of Veterinary Medicine University of Utrecht Utrecht, The Netherlands Guido Camps MS Department of Clinical Sciences of Companion Animals Faculty of Veterinary Medicine University of Utrecht Utrecht, The Netherlands Marijn van Delden DVM Department of Clinical Sciences of Companion Animals Faculty of Veterinary Medicine University of Utrecht Utrecht, The Netherlands Gert ter Haar DVM, PhD, DipECVS, MRCVS Department of Clinical Sciences of Companion Animals Faculty of Veterinary Medicine University of Utrecht Utrecht, The Netherlands and Department of Veterinary Clinical Sciences Royal Veterinary College University of London Hertfordshire, United Kingdom Tosca Hengel DVM Department of Clinical Sciences of Companion Animals Faculty of Veterinary Medicine University of Utrecht Utrecht, The Netherlands Jolle Kirpensteijn DVM, PhD, DipACVS, DipECVS Department of Clinical Sciences of Companion Animals Faculty of Veterinary Medicine University of Utrecht Utrecht, The Netherlands Tjitte Reijntjes DVM Department of Clinical Sciences of Companion Animals Faculty of Veterinary Medicine University of Utrecht Utrecht, The Netherlands Rick F. Sanchez DVM, DipECVO, MRCVS Department of Veterinary Clinical Sciences Royal Veterinary College University of London Hertfordshire, United Kingdom 7 Foreword Wound management and reconstructive surgery are challenges that small animal practitioners encounter on a regular basis. The techniques for dealing with these challenges involve both science and art, and the practitioner must have an understanding of both to attain a cosmetic and functional result from his/her efforts. This textbook provides practitioners with information to help attain such results. The authors’ interests and abilities in small animal surgery underlie the preparation of the book. Professor Jolle Kirpensteijn has a worldwide reputation for his expertise in surgical oncology and reconstructive surgery. His service as president of the World Small Animal Veterinary Association attests to his reputation. His experience and his teaching ability at the university and at inter - national levels well qualify him to prepare a book of this nature. Dr Gert ter Haar’s credentials reflect his interest and high qualifications in veterinary surgery and in particular veterinary ear, nose and throat surgery. His presidency of the International Veterinary Ear, Nose, and Throat Association indicates his renown in the latter field. Thus, prepa - ration of this book has been in the hands of two well-qualified individuals. The book’s design is to give the practitioner information on techniques and materials to manage wounds in preparation for reconstructive surgery and then to provide step-by-step guidance in the various procedures needed to perform the recon - struction. The content of the book is thorough, covering the basics of anatomy and wound healing and progressing on to management, reconstruction and aftercare of wounds. The topics and techniques are not only inclusive, but they are arranged in a very organized way. For example, reconstructive techniques are arranged anatomi cally. If a prac - titioner is presented with a wound on a certain body part, he/she can go to that section of the book to see what the options are for reconstruction. The authors strongly emphasize the use of various skin flaps for reconstruction. The advantage of flaps is their potential for maintaining a blood supply and, therefore, viability at all times during transfer and healing. Because ‘a picture is worth a thousand words’, the use of high-quality pictures in this step-by-step approach makes the book very user friendly. Steven F. Swaim DVM, MS Professor Emeritus Department of Clinical Sciences and Scott-Ritchey Research Center College of Veterinary Medicine Auburn University, Alabama, USA 8 Abbreviations ASA acetylsalicylic acid ATP adenosine triphosphate EDTA ethylenediamine tetra-acetic acid EGF epidermal growth factor FGF fibroblast growth factor GM-CSF granulocyte–macrophage colony- stimulating factor HBOT hyperbaric oxygen therapy IFN interferon IL interleukin IM inflammatory mediator IP inducible protein LLLT low-level laser therapy LRS lactated Ringer’s solution MCP monocyte chemoattractant protein MIP macrophage inflammatory protein-1 MMP matrix metalloproteinase MSRA methicillin-resistant Staphylococcus aureus NAP neutrophil-activating peptide NSAID nonsteroidal anti-inflammatory drug PDGF platelet-derived growth factor PF4 platelet factor 4 PMN polymorphonuclear cell PSIS porcine small intestinal submucosa SFAF skin fold advancement flap SSD silver sulfadiazine TAO triple antibiotic ointment TCC tripeptide-copper complex TGF transforming growth factor TNF-! tumour necrosis factor alpha TNP topical negative pressure (therapy) VEGF vascular endothelial growth factor Chapter 1 Introduction 9 Gert ter Haar, Sjef C. Buiks, Marijn van Delden, Tjitte Reijntjes, Rick F. Sanchez and Jolle Kirpensteijn • Anatomy • Blood supply • Skin tension • Tension-relieving suture patterns • Skin flaps and their classification • Reconstruction of the head • Eyelid reconstruction techniques • Reconstruction of the neck and trunk • Reconstruction of the forelimb • Reconstruction of the hindlimb • Wound closure techniques • Complications in performing plastic and reconstructive surgery • References Introduction10 In the last two decades, wound management and skin reconstructive techniques for dogs and cats have advanced dramatically and many articles and several textbooks and manuals dealing with wound reconstruction and wound closure tech niques have been published. The aim of this book is not to provide the reader with in-depth knowledge on skin reconstruction techniques or theoretical background information, but to describe in detail, step by step, the most commonly used recon structive techniques in dogs and cats. How ever, the basic knowledge necessary to understand and use the information provided in this book will be discussed. The basic anatomy and physiology of the skin with regard to cutaneous blood supply and skin tension lines are discussed in this chapter. A general description of reconstructive terminology, including a classification of the different types of flaps and skin grafts used in small animal recon structive surgery, is also included. An introduction to these flaps and skin grafts is provided as well as information regarding their use in specific locations on the body. Anatomy The skin of dogs and cats is quite different from human skin.Skin thickness, hair growth and circulation vary regionally between species and between dog and cat breeds to some degree.1,2 The skin consists of two main layers, the epidermis and the dermis.3–5 The general composition of the outer layer, the epidermis, is of avascular keratinized stratified squamous epithelium. The thicker vascular dermis lies underneath the epidermis and consists of tough fibroelastic tissue with a supportive and nourishing function. The dermis rests on a layer of loose connective tissue, known as the subcutis or hypodermis, which is composed of adipose tissue, the cutaneous trunci muscle (where present) and direct cutaneous arteries and veins. This layer is particularly abundant in most dogs and cats, but the quantity and elasticity of the skin will vary depending on the breed and on the physical condition of the animal.1,3 Variations in structure are present at different sites of the body surface. For example, the nose and footpads have a thick protective keratin layer, while the skin between the hindlimbs is fairly thin and sparsely haired. In addition, in most skin areas there are specialized epithelial appendages, such as hair follicles and sebaceous glands.6 The eyelids are dorsal and ventral folds of thin skin that are contin - uous with the facial skin, and their free edges meet to form the lateral and medial canthi.7 Histo- logically, the lids may be divided into four portions: the outermost layer of typical skin, the orbicularis oculi muscle layer, a stromal layer that contains a tarsal plate near the eyelid edge, and the innermost layer of palpebral conjunctiva.7 Blood supply Musculocutaneous vessels are the primary vessels supplying the skin in humans, but they play only a minor role in dogs and cats, rendering certain skin grafting techniques commonly used in man of limited use. In dogs and cats, direct cutaneous arteries are responsible for supplying large areas of skin. They run parallel to the skin in the hypo - dermis and arise from perforator arteries (1). Musculocutaneous arteries, which run perpen - dicular to the surface of the skin, branch off the perforator arteries and supply small portions of the skin (1). 1 Diagram depicting the unique vascular supply to the animal (feline and canine) skin and underlying tissues. 1, epidermis; 2, subcutis; 3, panniculus muscle; 4, skeletal muscle; a, superficial plexus; b, middle plexus; c, deep or subdermal plexus; d, segmental artery; e, perforator artery; f, direct cutaneous artery. The perforator arteries that supply the skeletal muscle terminate as small musculocutaneous arteries perpendicular to the skin after supplying their direct cutaneous arteries. The direct cutaneous arteries branch to form a deep, middle and superficial plexus.9 1 2 3 4 d ee a b c f 1 Introduction 11 Terminal arteries and veins branch from the direct cutaneous vessels and form the subdermal (deep or subcutaneous) plexus, cutaneous (middle) plexus and subpapillary (superficial) plexus (1).2–4,8,9 When a cutaneous trunci muscle is present, the subdermal plexus lies both superficial and deep to the muscle. The vessels of the subdermal plexus also run in the subcutaneous fatty tissue of the middle and distal portion of the limbs, where the cutaneous trunci muscle is absent. The superficial and middle plexuses lie within the dermis. The capillary loop system that originates from the superficial plexus and supplies the epidermis is poorly developed in dogs and cats compared to man, apes and swine.3 The subdermal plexus in dogs and cats is therefore of major importance in reconstructive skin surgery and should always be preserved when undermining skin for local flaps, especially when no direct superficial arteries can be incorporated into the proposed flap. Axial pattern flaps are based on direct cutaneous arteries and veins that supply a specific region of dermal tissue. Since the terminal branches of these vessels supply the subdermal plexus, axial pattern flaps have better perfusion than local flaps and are widely used in veterinary reconstructive surgery. The main canine integu - mentary vasculature, with its superficial arteries, is illustrated in 2.10 2 Topographical anatomy of the superficial arteries of the canine skin used in axial pattern flaps. 1, facial; 2, superficial temporal; 3, caudal auricular; 4, superficial cervical branch of omocervical; 5, cutaneous branch of thoracodorsal; 6, lateral thoracic; 7, superficial brachial; 8, cranial superficial epigastric; 9, caudal superficial epigastric; 10, deep circumflex iliac; 11, cutaneous branches of superficial lateral coccygeal; 12, medial genicular; 13, saphenous.10 1 2 3 4 5 6 8 9 10 11 12 13 7 2 Introduction12 Skin tension Tension on the wound edges is the most common reason for skin reconstructions to fail and occurs when insufficient skin is available to close the initial defect. Closing wounds under tension, particularly on extremities, may create vascular and lymphatic compromise to distal areas or reduce perfusion to wound edges, thus causing delayed healing or wound dehiscence.11,12 Eyelid reconstruction is further complicated by the fact that tension and scar formation can interfere with eyelid movement and affect corneal function. The elasticity of canine and feline skin is primarily the result of the lack of firm attachment of the subcutis to the bone, muscle and fascia. The skin is loose and abundant on most parts of the body, particularly on the neck and trunk, but is less pliable on the limbs, tail and head, especially around the bridge of the nose, nasal planum and medial canthi. This is the result of linear alignment of fibrous tissues within the skin in this area. The skin tension lines have fixed directions on the topographical anatomy of the dog.1,5,13–15 In breeds with abundant skin (e.g. the Shar Pei), tension lines are of less importance when considering recon - structive surgery. The tension lines of the head and neck region resemble the orientation of the underlying muscles (3). The tension lines of the trunk are perpendicular to the body axis and the tension lines 3 Skin tension lines of the head, neck, trunk and limbs in the dog.13 The tension lines of the head and neck region resemble the orientation of the underlying muscles, while those of the trunk are perpendicular to the body axis. The tension lines of the limb are generally parallel to the long axis of the limb on the cranial surface, but perpendicular to the long axis of the limb laterally and caudally. 3 Introduction 13 of the dorsal thoracoabdominal region are parallel to the body axis. The tension lines of the limbs are generally parallel to the long axis of the limb on the cranial surface, but perpendicular to the long axis of the limb on the lateral and caudal surfaces (3).13 Generally, incisions should always be made parallel to tension lines to minimize wound tension during closure. Incisions that are made at an angle or perpendicular to these lines may result in wound deformation, wound dehiscence and necrosis.16 If incisions cannot be made parallel to the tension lines, methods to reduce skin tension should be employed on closure. These include (from simple to more advanced techniques) undermining the wound edges, selecting tension-relieving suture patterns, using tension-releasing incisions, or skin stretching and tissue expansion techniques. If these methods do not allow primary closure of the wound, second intention healing or reconstruction with skin flaps or grafts have to be considered. Tension-relieving suture patterns Mild tension on skin wound edges can usually be relieved by using subdermal sutures, including the strong subdermal fascia. The subdermal fascia tolerates tension better than subcutaneous tissue or the skin itself. Walking sutures in successive rows can be used to relieve mild to moderate tension. They gradually advance the skin from the edge of a wound towards the centre (from both sides). Walking sutures are placed throughthe fascia of the body wall at a distance closer to the centre of the wound than the bite through the subdermal fascia (see Chapter 3).1,5 The most commonly used external tension- relieving suture is the vertical mattress suture, but horizontal mattress sutures, with or without rubber tubing stents, and far-near-near-far or far-far-near- near suture patterns can be used as well. Primary wound closure and second intention healing are discussed in Chapter 2, and tension-releasing incisions, including releasing incisions, V-Y plasties and Z plasties, are discussed in Chapter 3. Dis - cussion of skin stretching and tissue expansion methods is beyond the scope of this book. Skin flaps and their classification Wounds can be closed by primary closure, delayed primary closure or secondary closure or they can heal by second intention (see Chapter 2).1,17 Skin flaps useful for primary or secondary closure of wounds of the integument can be classified using different criteria (e.g. based on location, blood supply or geometric shape). Classification based on the blood supply of the flap distinguishes subdermal plexus flaps from axial pattern flaps. Subdermal plexus flaps are based on local skin vasculature from the flap base, whereas axial pattern flaps are based on a direct cutaneous artery and vein. Erroneously, the term ‘pedicle flap’ is sometimes used as a synonym for a subdermal plexus flap, but pedicle flaps normally are based on musculocutaneous vessels, which are of minor importance in dogs and cats, as discussed above.5 The principle behind the technique is that local skin in an area with relative abundance or elasticity is used to close the primary wound. The created secondary wound can be closed relatively tension free. Subdermal plexus flaps are easy to perform and often recreate the appearance of the original hair coat as well. However, they cannot be performed in areas with movement or increased tension. Additionally, the vascularity of the flap often limits its length. A flap with a direct cutaneous artery included has a better chance of survival than flaps without. Increasing the length of the flap or failing to include sufficient vascularity to the flap will increase the chance of dehiscence of the tip of the flap. The wider the base, the more chance that a direct cutaneous branch is included in the flap, thus improving viability. Subdermal plexus flaps can be subdivided into advancement flaps, rotation flaps, transposition flaps and interpolation flaps:18,19 • Advancement flaps are formed in adjacent skin by making slightly diverging incisions from the wound to the flap’s base, parallel to the tension lines, to allow advancement into the wound. The U-flap or French flap is a skin flap that is mobilized by undermining and advancing the skin in the direction of the wound axis. The indications for this type of flap include relatively square wounds and tension-free skin in the direct vicinity of the wound. Slightly divergent incisions will broaden the skin flap base. Bilateral U-flaps will create an H-flap, decrease tension and improve viability. Many variations of this flap type, including the V-Y, Z, reading man flap and rotation flaps, have been described. • Rotation flaps are local subdermal flaps that are pivoted over a defect with which they share a common border. • Transposition flaps are rectangular local subdermal flaps that bring additional skin into defects when transposed, with one edge of the flap being a portion of the original defect.5 • Interpolation flaps are rectangular flaps that are rotated into a defect with the pedicle passing over intact skin and usually sutured into a tube. The skin fold advancement flap (SFAF) is a special subdermal plexus flap that uses the abundance of skin in the region of the proximal or caudal parts of the limbs (skin fold) to close inguinal or sternal defects.20 Introduction14 Axial pattern flaps contain a specific cutaneous artery, vein and nerve that supply a specific region of dermal tissue. Therefore, axial pattern flaps have a more robust blood supply compared with randomly chosen local flaps, which rely on the subdermal plexus for their blood supply. When surrounding tissue has been excised from the supplying artery, but the flap remains attached to the donor bed by this cutaneous vessel, the flap is called an island or insular flap. A peninsular flap remains attached to the skin surrounding the cutaneous artery.21 Flaps created in adjacent skin are called local flaps, of which the advancement, rotation and transposition flaps are examples. Flaps where the donor site is distant from the recipient (defect) area are called distant flaps. They usually require multiple-stage reconstruction and transfer, but can be transferred in one stage by microvascular anastomosis of an artery and vein. The inter pola- tion flap, or tubed pedicle flap, is an example of a distant flap. A tubed pedicle flap is used to walk an indirect, distant flap to a recipient site (see Chapter 3). Pouch flaps (bipedicle) and hinge flaps (single pedicle) are other distant flaps used to reconstruct skin defects on the distal extremities. Chapter 4 presents the current knowledge on microvascular transfers, provides background information on transfers and location of recipient vessels, describes the most successful techniques used in veterinary medicine and provides a detailed overview of the results of published scientific articles in this field. Apart from these microvascular techniques, free avascular skin grafts can be used. They are most commonly used for defects that cannot be reconstructed by direct apposition of skin flaps (e.g. on the limbs). Skin grafts are segments of epidermis and dermis that are completely detached from the donor site (and donor vessels) and transferred to a recipient site. Most skin grafts used in dogs and cats are derived from the same animal (autogenous). Allografts (same species, different individual) and xenografts (different species) have been described, but are not used routinely. Skin grafts can also be classified as full or split thickness. Full-thickness skin grafts incorporate the entire dermis and epidermis and are more easily harvested by veterinary surgeons who do not have special equipment than split-thickness grafts. Skin grafts are further classified as sheet, mesh, strip or seed depending on the configuration of the graft.11,15,17,22 Of these, full-thickness mesh grafts are preferred for most wound reconstructions because of their ease of use, success of graft take and final cosmetic outcome. Mesh grafts are formed by placing multiple staggered rows of parallel incisions through the graft to allow expansion. Additionally, the release of fluid (serum, blood and exudate) produced by the host site is facilitated. This mesh graft technique is also described in Chapter 4. Flaps that contain tissue other than skin and subcutaneous tissue are called compound or composite flaps and may include muscle (myocutaneous), cartilage or bone. When only muscle is used, flaps are referred to as muscle flaps. They have an excellent blood supply and tissue volume and can be used for rebuilding defects of the trunk, abdomen and limbs.23 Myocutaneous or musculocutaneous flaps are compound flaps in which a skeletal muscle is elevated with the over - lying skin. These flaps have enjoyed considerable popularity in human reconstructive surgery and have clinical potential in small animal reconstructive surgery as well. Several individual muscles in the dog and cat are expendable without sacrificing regional function and could therefore be used. However, myocutaneous flaps are more technically demanding to perform; in most cases, local flaps, axial pattern flaps or free grafts can and should be used instead. Muscle and myocutaneous flaps are mainly used for recon - struction of the trunk. They are described in detail in Chapter 7 and include the external abdo minal oblique and tensor fascia lata muscle flaps and the cutaneous trunciand latissimus dorsi myocut - aneous flaps. The latissimus dorsi flap is suitable for closing defects on the trunk and on the forelimb as low as the elbow joint. The cutaneous trunci flap is a thinner flap and can be used to close defects on the thoracic and abdominal region as well as large wounds more distal on the forelimb. The latter flaps have great potential because of their size, ease of elevation, expendability and versatility. Whereas it was previously assumed that the latissimus muscle had to be included when har vesting these com - pound flaps in order to reduce flap necrosis, no significant differences were found in flap survival rates between cutaneous trunci and latissimus dorsi flaps.24 Finally, omental flaps can be used to cover soft tissue defects. As with muscle flaps, they enhance healing by combating infection, controlling adhe - sion and contributing to circulation and drainage. Selection of a particular technique is influenced by the size and location of the wound and the availability of adjacent donor skin. In most instances, more than one option is available and some wounds may require a combination of flaps.21,23 The most commonly used reconstructive Introduction 15 techniques are described in this book. The relatively easy reconstruction techniques that can be performed on any part of the body are discussed in Chapter 3, starting with the simplest techniques and progressing to the more complex procedures. Reconstruction of specific anatomical areas is sub - sequently discussed in Chapters 5–9, describing the flaps from cranial to caudal and from proximal to distal. Chapters 5 and 6 describe reconstruction of the facial area (head and eyelids, respectively), Chapter 7 describes reconstruction of the neck and trunk and Chapters 8 and 9 describe reconstructions of the forelimb and hindlimb, respectively. Reconstruction of the head Reconstruction of facial defects is often required after radical resective surgery of tumours, for closure of traumatic wounds, for the repair of burns or chemical damage to the skin and for a variety of palpebral problems. However, facial defect reconstruction can be very challenging, as not only is cosmesis of importance to owners, but the repair of defects in close proximity to the eyes, nostrils, ears and lips must provide for normal function of these structures and prevent secondary problems.22 The specificity and complex nature of eyelid reconstructive surgery and how it relates to surface ocular problems is discussed in a separate, dedicated chapter (Chapter 6). The bridge of the nose is more difficult to reconstruct than other areas of the face due to a paucity of local tissues. A modified nasal rotation flap (see Chapter 5) has been adapted by the authors for use in veterinary patients as it allows for a cosmetic closure of this difficult area using local tissues. Both unilateral and bilateral versions of this flap are described. As lips often have an abundance of loose skin, especially in dogs, most lip defects can easily be reconstructed using geometric closure techniques and advancement of local tissues. With the help of surgical textbooks, simple rectangular and wedge resections should not create a problem for veterinary surgeons. Full-thickness labial advancement of the lower and upper lip, buccal rotation and labial/buccal reconstruction with transposition skin flaps are more elaborate surgical techniques and are discussed in Chapter 5. Most other facial defects can be closed using local available tissues. Subdermal plexus flaps and axial pattern flaps are the most useful techniques for this purpose. Examples of subdermal plexus flaps commonly used in this area are the transposition flap, the rotation flap and the advancement flaps. These techniques are described in Chapter 3. The three axial pattern flaps that can be used for the reconstruction of large facial defects are the facial artery, superficial temporal and caudal auricular axial pattern flaps, all of which are described in Chapter 5. The omocervical axial pattern flap can be used for reconstruction of the caudal parts of the head in some patients, but is more commonly used in the neck area and therefore described in Chapter 7. Finally, in addition to the above-mentioned techniques, defects involving the auricle can be closed using subdermal plexus flaps. When small avulsions of the ear heal by second intention, the wound margins will contract, leaving a cupped or folded ear. The treatment of small avulsions of the pinna is purely cosmetic (i.e. resection of the surrounding tissue to form a new contour of the pinna). This flap is described in the literature as a pedicle flap for repair of large defects of the ear, using skin located on the neck and/or the dorsum of the head, and it is discussed in Chapter 5. Eyelid reconstructive techniques There are over 20 individually recognized techniques for surgery of the eyelids in the veterinary literature. This book describes only those that pertain to the reconstruction of large eyelid defects, whether caused by aplasia, trauma or tumour removal. Additionally, flaps designed for the reconstruction of eyelid shape and position relative to the eye are included. There are several points that apply specifically to eyelid surgery and must be considered by the surgeon during eyelid reconstruction. Eyelid tissue is extremely delicate and very well perfused. Eyelids heal relatively fast, but they also swell markedly in the postoperative period. Although swelling is usually a short-lived problem, it can lead to an inability to blink, unwanted trichiasis (skin hairs that contact the eye) and patient discomfort. Until swelling subsides, the use of a temporary tarsorr - haphy can prove very helpful in such cases. Maintenance of eyelid function and anatomy must be considered by the surgeon when per - forming eyelid reconstructive surgery. The eyelids serve a very important function in keeping the eye protected and in spreading the tear film and removing debris from the corneal surface. Direct closure of an eyelid defect should only be attempted when the defect accounts for less than 25% of the length of the eyelid, as closure is unlikely to interfere with eyelid function in these cases.25 Closure of larger defects requires reconstruction with other techniques such as Z- and H- plasties and flaps such as the rhomboid flap, lip-to-eye Introduction16 mucocutaneous subdermal plexus rotating flap, modified cross-eyelid flap and superficial temporal artery axial pattern flap. As the upper eyelid is more mobile than the lower eyelid, some of these procedures are designed to favour its complete reconstruction by using tissue from the third eyelid or the lower eyelid. Reconstructions that allow for an eyelid margin that is as anatomically correct as possible are pre - ferred. However, recreating a hair-free eyelid margin can be difficult, as many techniques resort to the use of peripalpebral skin. In order to resolve this problem, some surgeons advocate suturing conjunctiva to the edge of the new eyelid tissue. Others (personal communication, Prof. M. Boevé) suggest cutting the edge of the transposed skin that serves as the new eyelid margin at a 45° angle to its surface so as to eliminate hair follicles from the transposed edge. As meibomian gland secretion prevents evaporative loss of the tear film, removal of a large percentage of the eyelid margin could predispose the eye to dryness.26 Therefore, tear film quality should be re-examined before and after surgery. Reconstruction is also indicated when misalignment of the eyelids with respect to the eye has developed over time (i.e. marked partial facial droop and upper eyelid entropion–trichiasis). This misalignment can cause corneal irritation and interfere with sight. The aim in such cases is to reconstruct the eyelids so that they are in an anatomically correct position, they fit the globe relative to its size and they do not shift away from the eye with a change in headposition. Lastly, the medially located puncta of the conjunctival side of the upper and lower eyelids are an essential part of the nasolacrimal duct system and should be preserved or reconstructed whenever possible. Large, nonabsorbable suture material may be used in punctal and canaliculi reconstruction by feeding the suture all the way to the nasal ostium and leaving it in place for re-epithelialization to occur around it. Other points to consider are not exclusive to eyelid surgery. Postoperative graft shrinkage may lead to graft deformation. However, although a small change in graft size may be relatively unimportant elsewhere, in the eyelid it can lead to trichiasis, ectropion, entropion, inability to blink and secondary corneal problems. These are painful and may compromise sight through pigmentary or ulcerative keratitis and scarring. Therefore, the eyelid reconstruction should always be slightly larger than the defect it is meant to fill and it should protrude approximately 1 mm from the wound margin to allow for tissue shrinkage.25 Absorbable and nonabsorbable suture materials may be used in eyelid reconstruction techniques, which often require a two-layer closure. Deep sutures should be absorbable and in either a simple interrupted or simple continuous pattern. Skin may be closed with absorbable or nonabsorbable material depending on the proximity of the suture material to the eye and how much patient cooperation is required to facilitate their removal. In this book, 6-0 polyglactin has been used for closure of deeper tarsoconjunctivae and skin in areas of close proximity to the eyelid margin. For skin closure in areas not near the eyelid margin, 5- 0 polyamide or similar has been used. Generally, when apposing two parts of the eyelid margin, a tarsal plate ‘holding’ suture with a buried knot is placed before alignment and apposition is achieved with a figure-of-eight suture pattern. Thin eyelids may only allow for a figure-of-eight pattern that has to hold, align and appose the tissue. Needle designs include reverse cutting and round choices. Magnification (2.5" to 4") is recommended when performing eyelid surgery as it helps the surgeon to visualize the entry and exit points of fine suture material and to identify delicate structures such as the lacrimal puncta. Finally, the skin should be prepared aseptically prior to surgery. However, soap-containing solutions should be avoided in areas near the eye. For eyelid and ocular surface preparation, dilute solutions of iodine in sterile saline are commonly used. A solution of iodine in saline in a ratio of 1:10 may be used for preparing the eyelid tissue and a 1:50 ratio may be used for preparing conjunctival surfaces; higher concentrations could be slightly irritating to the conjunctival and corneal epithelium. Conjunctival tissues should be carefully and thoroughly irrigated. Sterile cotton buds may be used with care if hairs and mucus need to be removed. Skin should be free of infection and prophylactic, postoperative, topical and oral antibiotics should be used as needed. Reconstruction of the eyelids is described in Chapter 6 and includes H-plasty, Z-plasty, semicircular flap, rhomboid flap, modified cross-lid flap, lip-to-eye flap and the superficial temporal artery axial pattern flap techniques. Reconstruction of misalignment of the eyelids with respect to the eye is also covered in Chapter 6. The selected techniques increase in complexity from the arrowhead method for correction of lateral canthal entropion involving the upper and lower eyelid, to the Stades technique for correction of upper eyelid entropion–trichiasis and the Munger–Carter flap adaptation of the Khunt–Szymanowski–Fox–Smith procedure. Introduction 17 Reconstruction of the neck and trunk Reconstruction of skin defects in the neck or trunk area is usually relatively easy in dogs and cats because of the considerable amount of loose skin in this area. In most cases, defects can be closed using local skin flaps. However, after radical resective surgery of tumours, for closure of large traumatic wounds or for reconstruction in areas with compromised blood supply, other techniques have to be used. In addition, reconstruction of the caudal part of the trunk, and in particular the perineal area, is more challenging because of less available skin. The axial pattern flaps that can be used for reconstruction of large defects in the neck or trunk area are the omocervical, the thoracodorsal and the cranial and caudal superficial epigastric flaps. The first three flaps are described in Chapter 7. The caudal superficial epigastric axial pattern flap is described in Chapter 9, since this versatile flap is more commonly used to close defects of the hindlimb. The muscle and myocutanous flaps that can be used for reconstruction of the neck and trunk in dogs and cats are also described in Chapter 7. They include the external abdominal oblique and tensor fascia lata muscle flaps and the cutaneous trunci and latissimus dorsi myocutaneous flaps. Reconstruction of surgical wounds in the perineal region is challenging, since local skin is often not applicable for local flaps because of a high risk of necrosis. However, an axial pattern tail flap, based on the lateral caudal arteries, can be used to close large caudodorsal trunk and perineal defects. The scrotal flap, used as a subdermal plexus flap, can also be used to close defects in the perineal area. Finally, excessive skin folds around the vulva require episioplasty or vulvoplasty in case of perivulvular dermatitis, but excessive skin here can also be used to close adjacent defects. Chapter 7 ends with a description of these three techniques. Reconstruction of the forelimb Reconstruction of skin defects of the forelimb, as described in Chapter 8, can be complicated because of the lack of loose skin and the fact that most axial pattern flaps will not be able to reach the distal part of the limb. In small lesions, defects can be closed using local skin flaps. However, after radical resective surgery of tumours, for closure of large traumatic wounds or for reconstruction in areas with compromised blood supply, other techniques have to be used. The axial pattern flaps that can be used for reconstruction of large defects in the forelimb include the omocervical, the thoracodorsal, the cranial superficial epigastric, the lateral thoracic and the brachial flaps. The latter will be discussed in Chapter 8. Both the peninsular and island varia - tions of the brachial axial pattern flap are described. The forelimb fold transposition flap technique utilizes the thin elastic skin fold of the forelimbs and is a skin fold advancement flap, not an axial pattern flap. Because of the sheer size of the flap, minor vessels run within the flap and even the lateral thoracic artery might be included. It is a versatile flap that can be used for defects of the upper arm or sternal region and is therefore described in Chapter 8. Two large myocutaneous flaps, the cutaneous trunci and latissimus dorsi myocutaneous flaps, can be created from the thoracolumbar region to close defects of the forelimb. Both flaps, but especially the thinner more mobile cutaneous trunci flap, can be used to cover defects near the elbow joint. Since they originate from the trunk and are also used to close defects of the trunk, these flaps are described in Chapter 7. The flexor carpi ulnaris muscle flap can be used in cases of chronic recurrent problems where other techniques have failed, or in cases with large defects of the antebrachium where skin and subcutis are lost and bone is visible. This muscle flap is more likely to stay attached and remain in place on a bony surface than skin flaps and is described in Chapter 8. Reconstruction of defects involving the foot are especially challenging. Many new techniques have been developed to close these defects with a better outcome than with local flaps, including fusion podoplasty, segmental pad transfer and phalangeal(toe) fillet flap. The toe fillet technique is specifically worth mentioning because of its versatility and excellent results. Either digit 1 or 2 and digit 5 can be used for this technique. All of the above- mentioned techniques are described in Chapter 8. Last, but not least, mesh grafting is often used for distal limb lesions, especially in cats, when no local tissue is available at all. This technique is described in Chapter 4. Reconstruction of the hindlimb Surgeons have more options for reconstruction of skin defects of the hindlimb than the forelimb. In small lesions, defects can be closed using local skin flaps. However, as with the forelimb, other techniques have to be used for closure of large wounds. The axial pattern flaps that can be used for reconstruction of large defects in the hindlimb include the deep circumflex iliac, the caudal Introduction18 superficial epigastric, the genicular and the reversed saphenous conduit flaps. The latter technique is unique because of the ligation of veins and arteries proximally, reversing the blood flow. An adequate blood supply is secured through anastomoses with other vessels. The hindlimb (flank) fold transposition flap technique utilizes the thin elastic skin flank fold of the hindlimbs in a similar way to the transposition flap of the forelimbs. This versatile flap can be used for defects of the upper limb or inguinal region. Both the unilateral and bilateral techniques are described in Chapter 9. Muscle flaps that can be used on the hindlimb are the cranial and caudal sartorius flaps. Options for reconstruction of defects of the foot of the hindlimb are similar to those of the forelimb. In addition to the techniques described in Chapter 8, metatarsal pad transfer as a salvage procedure for extensive damage to the underfoot is described in Chapter 9. Wound closure techniques Most plastic surgery and reconstructive techniques used in dogs and cats involve the creation of new surgical wounds. The general surgical principles of using aseptic techniques, proper instruments and delicate tissue handling while creating a surgical wound apply here as well. In addition, appropriate suture materials and suture techniques must be used for reconstructive surgery. For a complete discussion of types of suture materials and suture techniques, the reader is referred to general surgical textbooks. The authors prefer to use monofilament absorbable suture material of the smallest size possible for apposition of subcutaneous tissues. Depending on the size of the animal, monofilament absorbable 2-0 to 4-0 suture material (e.g. polyglecaprone) is advised. Both interrupted and continuous suture patterns can be used. The inter - rupted suture technique can be modified to allow for a decrease in skin tension; for example, using a walking suture pattern or mattress suture pattern as discussed above. For most types of grafts, skin closure using nonabsorbable suture material in an interrupted pattern is the preferred option, again with a preference for monofilament over braided material. Nonabsorbable monofilament 3-0 or 4-0 suture materials (e.g. polyamide) generally suffice. However, where appropriate, straight wounds can be closed by suturing only the subcutaneous or subcuticular layers in a continuous pattern, resulting in a highly cosmetic outcome. Mono fila- ment absorbable material is most commonly used. Finally, tissue glue or skin staples can be used for skin closure in reconstructive surgery; however, the cost of tissue glue limits its use, as generally large wounds have to be closed. Skin staples are increasingly used, since they are easy to insert and allow for rapid closure without loss of safety or cosmetic effect. The end result of stapling the skin is no worse than that of interrupted skin sutures, but it is less cosmetically attractive than using a continuous subcutaneous suture pattern. The in - creased cost of staples compared with normal suture material usually outweighs the cost of the increased anaesthesia and surgical time required when large flaps have to be sutured. In this book, both interrupted skin sutures and staples have been used for skin closure. Complications in performing plastic and reconstructive surgery Complications of wound closure in plastic and reconstructive surgery are similar to those in general soft tissue surgeries and include wound dehiscence, infection, haematoma or seroma form - ation and excessive scar formation. In addition, closure of wounds on the extremities under excessive tension can lead to oedema or circulatory compromise of the tissues distal to the wound.15,17,21,27,28 Most complications can be avoided by proper preoperative planning and skin mobility assessment, by using a meticulous surgical technique and achieving haemostasis. The chances of flap survival will increase if the size and localization of the wound is suitable for receiving the flap, if the wound is neither contami - nated nor infected and if the wound is not more than 4–6 hours old. It is also important that the recipient bed for the flap is properly prepared. Reconstruction can be carried out immediately after tumour resection or on a fresh wound. In other cases it is advisable not to close the wound too soon and to wait until contamination is resolved, the local circulation has improved and a healthy gran - ulation bed has formed. Contaminated or infected wounds should be managed (delayed closure) for a few days with medications and bandages until all tissues are ready for closure (see Chapter 2). Infection is, next to excessive skin tension, the major cause of flap rejection. Thus, the preparation of a healthy wound bed is one of the most important aspects of reconstructive surgery. Another potential complication is the development of dead space, which can lead to the formation of abscesses, seromas or haem - atomas.15,17,21,27,28 Formation of dead space can be overcome by placing drains, using subcutaneous and walking sutures and applying bandages. The authors recommend the use of either passive or active drains whenever possible, while taking care not to damage the blood supply at the base of the flap by making exit ports. Whenever possible skin flaps should be bandaged after surgery to provide support, prevent (self- inflicted) trauma and allow for absorption of wound fluids. The wound and flap should be exam - ined at regular intervals postoperatively to check if there is oedema because of impaired venous or lymphatic outflow, infection or colour changes. Tension can be relieved by making releasing incisions. Some degree of ischaemia resulting in necrosis may occur in any flap. With partial- thickness necrosis, the necrotic tissue usually sloughs spontaneously and re-epithelialization occurs rapidly from the graft margins. When necessary, gentle wound debridement can be helpful. Full-thickness necrosis is best treated by wound debridement and proper wound manage - ment (see Chapter 2). Clean wounds can be allowed to heal by second intention healing or a new reconstructive procedure can be planned. References 1. Swaim SF, Henderson RA (1997) (eds) Small Animal Wound Management, 2nd edn. Williams & Wilkins, Philadelphia, pp. 143–275. 2. Pavletic MM (1991) Anatomy and circulation of the canine skin. Microsurg 12:103–112. 3. Dyce KM, Sack WO, Wensing CJG (1996) (eds) Textbook of Veterinary Anatomy. WB Saunders, Philadelphia. 4. Scott DW, Miller WH (1995) Muller & Kirk’s Small Animal Dermatology, 5th edn. WB Saunders, Philadelphia, pp. 45–46. 5. Hedlund CS (2002) Surgery of the integument. In: Small Animal Surgery, 2nd edn. (eds TW Fossum, CS Hedlund, DA Hulse et al.) Mosby, St. Louis, pp. 134–228. 6. Young B, Heath JW (2000) Wheater’s Functional Histology, 4th edn. Churchill Livingstone, Edinburgh, p. 157. 7. Samuelson DA (2007) Ophthalmic anatomy. In: Veterinary Ophthalmology, 4th edn. (ed KN Gelatt) Blackwell Publishing, Ames, pp. 37–148. 8. Pavletic MM (1993) The integument. In: Textbook of Small Animal Surgery,2nd edn. (ed D Slatter) WB Saunders, Philadelphia, pp. 260–268. 9. Daniel RK, Williams HB (1973) The free transfer of skin flaps by microvascular anastomoses: an experimenal study and a reappraisal. Plast Reconstr Surg 52:16–31. 10. Evans HE (1993) Miller’s Anatomy of the Dog, 3rd edn. WB Saunders, Philadelphia. 11. Smeak D (2006) Reconstruction techniques using tension relieving and axial pattern flaps. Proceedings of 13th ESVOT Congress, pp. 146–150. 12. Anderson D (1997) Practical approach to reconstruction of wounds in small animal practice. Part 2. In Pract 19:537. 13. Oiki N, Nishida T, Ichihara N et al. (2003) Cleavage line patterns in Beagle dogs: as a guideline for use in dermatoplasty. Anat Histol Embryol 32:65–69. 14. Irwin DH (1966) Tension lines in the skin of the dog. J Small Anim Pract 7:593–598. 15. Hedlund CS (2006) Large trunk wounds. Vet Clin North Am Small Anim Pract 36:847–872. 16. Straw R (2007) Reconstructive surgery in veterinary cancer treatment. Proceedings of the World Small Animal Veterinary Association, Sydney. Introduction 19 Introduction20 17. Pavletic MM (2010) Atlas of Small Animal Wound Management and Reconstructive Surgery, 3rd edn. Wiley–Blackwell, Ames, pp. 31–50. 18. Gregory CR, Gourley IM (1990) Use of flaps and/or grafts for repair of skin defects of the distal limb of the dog and cat. Probl Vet Med 2:424–432. 19. Pope ER, Swaim SF (1986) Wound management in cats. Vet Med 81:503. 20. Hunt GB, Tisdall PL, Liptak JM et al. (2001) Skin-fold advancement flaps for closing large proximal limb and trunk defects in dogs and cats. Vet Surg 30:440–448. 21. Dupré G (2007) Complications in plastic and reconstructive surgery. Who is guilty: the patient, the owner, the vet? Proceedings of the 56th Congresso Internazionale Multisala SCIVAC, Rimini, pp. 207–208. 22. Pope ER (2006) Head and facial wounds in dogs and cats. Vet Clin North Am Small Anim Pract 36:793–817. 23. Szentimrey D (1998) Principles of reconstructive surgery for the tumor patient. Clin Tech Small Anim Pract 13:70–76. 24. Pavletic MM, Kostolich M, Koblik P et al. (1987) A comparison of the cutaneous trunci myocutaneous flap and latissimus dorsi myocutaneous flap in the dog. Vet Surg 16:283–293. 25. Stades F, Gelatt KN (2007) Eyelid surgery. In: Veterinary Ophthalmology, 4th edn. (ed KN Gelatt) Blackwell Publishing, Ames, pp. 563–617. 26. Ofri R, Orgad K, Kass PH et al. (2007) Canine meibometry: establishing baseline values for meibomian gland secretions in dogs. Vet J 174:536–540. 27. Degner DA (2007) Facial reconstructive surgery. Clin Tech Small Anim Pract 22:82–88. 28. Pope ER (1996) Plastic and reconstructive surgery. In: Complications in Small Animal Surgery. (eds AJ Lipowitz, DD Caywood, CD Newton, A Schwartz) Williams & Wilkins, Baltimore, pp. 641–662. • Introduction • Wound healing • Wound management • A protocol for wound management in dogs and cats • Cost-effectiveness and patient and owner benefit • Conclusion/summary • References Chapter 2 Wound management: a new protocol for dogs and cats Tosca van Hengel, Gert ter Haar and Jolle Kirpensteijn 21 Introduction Wounds can be defined as injuries to the body that result in disruption of the continuity of the body structure.1 They are encountered frequently in veterinary practice and therefore a veterinarian should be familiar with all processes involved in wound healing and the options for wound management. Although there are differences in the types of wounds, which include incisions, abrasions, burns, avulsions, ruptures, punctures, contusions, lacerations and bite and shot wounds, the main principles of wound healing are the same for all types. Wounds can be classified in several ways. One of the most important distinctions to make is between open and covered, or closed, wounds. In closed wounds the superficial layer is still intact and protects the wound against contamination; in open wounds there is a disruption of the skin or mucous membrane. Further classification of open wounds can be based on the degree of contamination, which partly depends on the duration of the injury:2–4 • Category 1. Clean wounds: nontraumatic wounds not involving the respiratory, oropharyngeal, gastrointestinal or urogenital organs with no visible contamination; within 0–6 hours after surgery. • Category 2. Clean-contaminated wounds: nontraumatic wounds where respiratory, oropharyngeal, gastrointestinal or urogenital organs are opened without spillage of contents; clean wounds in which a drain is placed; in cases of small breaches in aseptic technique; within 0–6 hours after surgery. • Category 3. Contaminated wounds: traumatic wounds less than 4–6 hours old; inflammatory processes without purulent exudate; procedures that are contaminated with contents of the gastrointestinal organs or infected urine; serious breaches in aseptic technique. • Category 4. Infected or dirty wounds: traumatic wounds more than 4–6 hours old or with obvious contamination or signs of infection (4); inflammatory processes with purulent exudate or necrotic tissue; perforation of the gastrointestinal organs or infected urogenital organs and serious faecal contamination. An infected wound contains more than 105 bacteria per gram of tissue. Wounds can also be classified by the length of time they have been present (acute or chronic wounds) and by the thickness of the skin surface that is lost (full-thickness or partial-thickness). In chronic wounds, underlying factors preventing wound healing can usually be identified and need to be addressed for standard treatment to be successful. With full-thickness skin loss the complete dermis and epidermis are lost, but with partial-thickness skin loss the dermis is still partly intact. Adnexal structures in the partly intact dermis can serve as a source for epithelial cells, which are needed for wound healing.3 Wound healing As stated above, all wounds heal in a similar fashion, divided into four distinctive phases. However, depending on the type of wound and its classification, one or several phases of wound healing can be accelerated, delayed or complicated by several factors. In addition, several phases of wound healing can be found at the same time in all wounds. Although the phases of wound healing are the same in dogs and cats, there are some important differences in wound healing between these two species and the clinician must take these into Wound management: a new protocol for dogs and cats22 4 An infected wound with a purulent discharge and partial dehiscence. 4 consideration.5–7 Every wound will follow the general wound healing pathway of four consecutive phases: the acute inflammatory phase; the breakdown or debridement phase; the reparation or proliferation phase; and the remodelling or maturation phase.2–4,8–11 To aid wound healing, to direct and stimulate the healing process and to make the right decisions in wound management, a clinician has to be familiar with these processes of wound healing. Inflammatory phase Directly after wounding, the wound fills with blood and lymph from damaged vessels. This is followed by an immediate vasoconstriction of the damaged vessels, mediated by catecholamines, serotonin, bradykinin, prostaglandins and histamine, which lasts 5–10 minutes and helps minimize blood loss.9 Subsequent vasodilation dilutes toxic substances, provides nutrients and results in blood clot formation mediated by activated platelets. The blood clot protects the wound, dries to form a scab and enables wound healing to proceed underneath it. Vasodilation also allows fluid containing cells, such as lymphocytes, polymorphonuclear cells (PMNs) and macrophages, and chemotactic factors, such as cytokines and growth factors, to reach the injured area.1,3,4,8,9 The activated platelets are also responsible for initiation of wound healing through the release of cytokines and essential growth factors. Within 24–48 hours, local monocytes migrate into the wound and become macrophages, whichalso produce a wide array of essential growth factors. Wound macro - phages, endothelial cells and fibroblasts mediate the healing process from this point on.1,3,4,8,9 The migration of PMNs, lymphocytes and macrophages is stimulated by chemotactic factors such as complement, growth factors and cytokines.1,3,4,8,9 Research has shown that PMNs, which dominate the wound in the early stages, are not essential in uncomplicated wound healing, but macrophages, more dominant from day 5 on, are needed.3,9,12 The mediators that initiate inflammation in healing wounds are soluble factors released by resident cells of the wound bed and by platelets and leucocytes delivered by the circulation after the disruption of intact skin. These factors initiate a series of events that attempt to stabilize the wound, remove invading organisms and return the wound to its pre-injury architecture. This depends on the production, regulation and control of inflammatory mediators (IMs).13 IMs are usually found in two groups of wound healing soluble factors: cytokines and growth factors. Cytokines are extremely potent and usually act within a short distance of their release as intracrine, autocrine or paracrine signals. They can be subcategorized as chemokines, lymphokines, monokines, interleukins (ILs) and interferons (IFNs).13–15 The growth factors that play essential roles in wound healing, such as platelet-derived growth factor (PDGF), epidermal growth factor (EGF), fibroblast growth factor (FGF) and vascular endothelial growth factor (VEGF), can be referred to as connective tissue growth factors given their function locally and rare systemic effects.13–15 The IMs currently known to be crucial to the wound healing process are IL-1, IL-2, IL-4, IL-6, IL-8, granulocyte–macrophage colony-stimulating factor (GM-CSF), G-CSF, M-CSF, macrophage inflammatory protein (MIP)-1, monocyte chemo - attractant protein (MCP)-1, neutrophil-activating peptide (NAP)-2, IFN-inducible protein (IP)-10, IFNs, transforming growth factor (TGF)-#, tumour necrosis factor alpha (TNF-!), platelet factor 4 (PF4) and PDGF.13,15 More specifically, in the inflammatory stage, platelets release PDGF, TGF-#, FGF and EGF, which orchestrate the early chemoattraction and activation of cells involved in wound healing. After clot formation, epithelial cells begin to migrate from the wound periphery onto the exposed tissue in response to EGF, TGF-!, TGF-#, GM-CSF and FGFs. These induce the epithelial cells to migrate and cover the wound. Fibroblast proliferation is stimulated by TGF-# and IL-1, angiogenesis is activated by EGF and IL-8, and neutrophil wound infiltration is triggered by TNF-! and NAP-2.13–15 The inflammatory phase is characterized by the five classical signs of inflammation (i.e. redness, pain, heat, swelling and loss of function; also known as rubor, dolor, calor, tumor and functio laesa, respectively). Debridement phase Necrotic or dead tissue impedes wound healing and therefore its removal is an essential phase in the healing process.8,9,16 This necrotic tissue is a stimulus for inflammation and provides a good environment for bacteria to proliferate. PMNs and macrophages have an important function in removing the debris and cleaning the wound and are regulated by the previously-mentioned cytokines and growth factors.13,15 As mentioned above, macrophages play the most important role by assuring cytokine secretion and secretion of proteinases and other proteolytic enzymes that digest damaged wound bed matrix and allow migration by other connective tissue cells. Wound management: a new protocol for dogs and cats 23 The inflammatory exudate formed in the previous phase provides all the necessary phagocytic cells and proteolytic enzymes to deal with the demar - cation. This phase ends with the rejection of nonvital tissue (5).4 In some instances these two phases are combined into one phase. The next phase, the proliferation phase, is marked by invasion of fibroblasts, accumulation of collagen and the formation of new endothelial structures. Proliferation phase Approximately 3–5 days after injury, the signs of inflammation subside, the wound becomes cleaner because of the debridement process and the repair of the wound can start. The proliferation phase can be divided into three processes (granulation, contraction and epithelialization) and is characterized by proliferation of fibroblasts and endothelial and epithelial cells.3,4,8,9 The period before these phases is sometimes called the lag phase because the wound does not gain strength in the first few days after wounding.9 Monocytes, after they have been activated to macrophages, produce their own growth factors, including PDGF, TGF-!, TGF-#, IGF-1, VEGF and TNF-! along with the growth factors produced by damaged parenchymal cells, and the stored growth factors released by stimulated platelets. These cytokines orchestrate the proliferative phase of wound repair. Fibroblasts invade the wound and begin to lay down new matrix mainly in the form of collagen and glycosaminoglycans. Concurrently, neovasculari - zation begins to take place and granulation tissue is formed.3,8,9,13 Granulation The main components of granulation tissue are fibroblasts and capillaries. The capillary network occurs through sprout formation of capillary endothelial cells on the wound surface.4 Endothelial buds and sprouts are formed through mitosis and these expand and contact other buds or already hollow capillaries.4 Next, the capillary network is intertwined with fibroblasts. The fibroblasts migrate from the surrounding tissues and develop from fibrocytes, but they also originate from undifferentiated pericapillary cells, mesenchymal cells and monocytes. Fibrin and fibronectin in the wound are important for the formation of granulation tissue because they serve as a framework to support inwardly growing cells.3,4,8,9 The fibroblasts produce collagen and fibrin is slowly replaced by the collagen deposited.17,18 The deposition of collagen is controlled by epithelial cells and fibroblasts themselves, which both have collagenase activity.3 Collagen production reaches its maximum on approximately the 9th day of wound healing, but the net collagen synthesis increases up to 4–5 weeks after injury.4 Endo- genously produced vitamin C is essential to the production of collagen.3 Once the wound is filled with granulation tissue, a reduction takes place of the number of cells and the amount of collagen fibres. Furthermore, the collagen fibres undergo continuous remodelling by breakdown and rebuild - ing of fibres.4 Granulation tissue is characterized by a red, irregular surface because of the newly formed capillary buds (6, 7). It is fragile tissue that functions as a barrier to infection.8,9,18 A healthy bed of granulation tissue acts not only as a barrier against environmental contamination, but also as a scaffold for migrating epithelial cells. The supply of nutrients, the removal of toxic metabolites and the presence of oxygen are the main factors that Wound management: a new protocol for dogs and cats24 5 A wound with obvious necrosis and advanced demarcation demonstrating the need for surgical debridement in order to allow continuation of wound healing. 5 determine how the barrier functions.3 However, hypoxia can stimulate the formation of new capillaries.18 Wound contraction The wound surface and the wound cavity become smaller because of the specific activities of fibroblasts with contractile properties during and after the formation of granulation tissue in the wound. These specialized fibroblasts, called myo - fibroblasts, are the main contributors, but normal fibroblasts are also capable of aiding wound contraction.3,4,8,17 Myofibroblasts attach themselves to the dermis under the skin edges and to the underlying fascia or panniculus muscle layer.3 They orientate themselves parallel to each other on the wound surface. After attaching they contract, pulling the adjacent skin to the centre of the wound.3Wound contraction thus involves a process that pulls the borders of the skin adjacent to the wound towards the centre of the wound. This centripetal movement is especially striking in areas of the body with loose skin (e.g. the trunk). The quantity and elasticity of the skin differ between species and breeds. Wound contraction normally begins 5–9 days after wounding.9 Wound contraction stops when the tension of the surrounding skin becomes too high or when the edges of the wound contact each other. If wound contraction is excessive, wound contracture can occur. This is a pathological process and results in limited motion of the underlying structures.11 Excessive granulation tissue can impede contraction by preventing the skin from gliding over the wound surface. Also, a normal amount of granulation tissue can impede wound healing when it is of poor quality.17 Another factor that can inhibit wound contraction is pressure on the wound, because the wound edges are pushed away from each other.17 When applying a bandage, it is recommended that pressure is kept off the wound by distributing it around the wound.17 After wound contraction, the surrounding skin has been thinned. This will be restored by pro - liferation of epithelial cells and connective tissue, called intussusceptive growth.3,8,18 Wound management: a new protocol for dogs and cats 25 6, 7 (6) A large burn wound before debridement. (7) The same wound after 4 weeks of intensive care demonstrating a healthy bed of granulation tissue. 6 7 Epithelialization Epithelialization occurs when there is a partial or full disruption of the epidermis. This process includes proliferation of basal epithelial cells from the adjacent skin edges and their moving over and adhesion to the surface of the wound (8).3,4,8 The cells fill in the area of the wound that is left after wound contraction, provided the area to be covered is not too large. The epidermal cells make use of the underlying fibroangioblast tissue layer, which needs to be healthy in order for proper epithelialization to occur. The activity of the epithelial cells leads to inhibition of the formation of granulation tissue and prevention of excessive formation of granu - lation tissue.4 In closed wounds, however, epithelial cells migrate over the exposed dermis and through the fibrin clot.8,18 The movement of new epithelium stops due to contact inhibition. The total duration of epithelialization can range from days to weeks, depending on wound size and the condition of the granulation tissue.8 During this stage of wound healing, concentrations of growth factors involved in earlier phases of wound healing are reduced, while others including TGF-# are increased. The surface of the wound that has become epithelialized is known as the epithelial scar and is Wound management: a new protocol for dogs and cats26 8 A wound showing healthy granulation (red) and advancing epithelialization (pink). 9 A wound that has healed by second intention demonstrating advanced maturation and obvious scar formation. thin and fragile.3 Therefore, care must be taken when applying bandages to wounds in this phase because migrating cells are easily removed from the surface when changing the bandage.4 Maturation phase The remodelling or maturation phase is charac - terized by increasing strength of the scar as a result of remodelling of tissue.4 Collagen III is replaced by the stronger collagen I, the collagen bundles become thicker and the number of cross-linkages between collagen fibres is increased.1,3,4,8,11,18 The newly formed collagen is arranged parallel to the tension lines of the skin.3,8 This phase can take several weeks to 1 year after the traumatic event, but ultimately the healed wound will never regain its original strength.9 In addition, the newly formed skin has no or insufficient hair follicles, sweat and sebaceous glands, poor moveability and elasticity and an absence of pigment (9).4 The signals for the remodelling phase are still largely unknown, but blocking TGF-# activity has been implicated in excessive scarring, suggesting that it may play a role in halting scar formation by encouraging cell apoptosis.15 8 9 Differences between acute and chronic wounds As mentioned above, wounds can be divided into acute and chronic wounds. Understanding the differences between these two types of wounds is important for proper wound management. In chronic wounds there is a lack of orderly pro - gression through the four phases of wound healing (10). The sequence of wound healing, described above, is disturbed. For instance, the wound fluid in chronic and acute wounds differs biochemically. In chronic wounds the levels of inflammatory cytokines are raised for a prolonged period and there seems to be an excess of matrix metalloproteinases (MMPs) and serine protein - ases.13,19 These lead to a breakdown of the matrix, which is needed for epithelialization, and to the breakdown of the growth factors and cytokines important for wound healing.19 An important cause of chronic wounds is infection, which causes a sustained inflammatory phase. Persistent inflammation results in further trauma to wound tissue and prevents healing.20 Many other factors influence wound healing including malnutrition, radiation, use of corticosteroids and underlying metabolic diseases.2,11,20 To resume the normal repair process, these factors need to be addressed. Differences in wound healing between dogs and cats For many centuries it was thought that wound healing was the same for all mammals. In the last decades researchers have discovered that although all species follow the same phases of wound healing, they do not all heal in the same way. Differences between horses and ponies and between rabbits and humans were found, and there also seemed to be differences between cutaneous wound healing in dogs and cats.5–7 Research into wound management has predominantly been in dogs. Recent studies in cats make previous assumptions that results can be extrapolated to cats questionable. A few studies have been carried out to investigate the differences between wound healing in dogs and cats. One of these differences is the vascular supply of the skin. One study showed that dogs appeared to have a higher density of tertiary and higher order vessels than cats. This was in accordance with a laser Doppler perfusion study, which concluded that the intact skin of cats was less perfused than the intact skin of dogs.5,21 Additionally, the breaking strength of a wound in cats is approximately 50% less than that in dogs 7 days after primary closure.5 There is also a difference in the rate and pattern of production of granulation tissue. The formation of granulation tissue takes longer in cats compared with dogs. In cats, granulation tissue first appears at Wound management: a new protocol for dogs and cats 27 10 A chronic nonhealing wound on the hock of a dog. the wound edges, in contrast to dogs where it appears simultaneously on the entire exposed surface.7 The colour of the granulation tissue is paler in cats.7 Rates of wound contraction, epithelialization and total healing are all reduced in cats compared with dogs.7 However, the role of subcutaneous tissue in wound healing in the dog and the cat is similar in both species.6 Complications in wound healing also differ between dogs and cats. Pseudohealing and formation of indolent pockets are much more common in cats.7 Pseudohealing refers to a sutured wound that appears well healed but, after removal of the sutures, dehiscence occurs under normal stresses.7 Pseudohealing is often observed with bite wounds. Indolent pockets, also called indolent ulcers, are chronic pockets in the subcutis that are lined with mature collagen and contain a thin, serous, modified transudate.7 Wound contraction does not occur in these wounds.17 Because of the lower breaking strength of sutured wounds in cats, some authors have advised leaving sutures for a few days longer in cats after surgery comparedwith dogs.7 This is especially important when larger parts of the subcutis have been removed during surgery. More research is needed to better understand the differences in wound healing between the two species and to translate them into practice. 10 Wound management Many of the wounds that the veterinarian is confronted with will heal naturally, but there are wounds that may need intervention (e.g. large wounds or necrotic and infected wounds). In addition, some wounds may heal better, quicker or have a better cosmetic outcome following some kind of stimulation. In patients presented with acute wounds that are still bleeding, the first step in wound management is to stop the bleeding. With major haemorrhage this can be performed by compression of the wounded area.4 For minor bleeding, the use of specialized dressings with haemostatic properties is possible (e.g. alginates with calcium, adrenaline-soaked gauzes or gelatin sponges).2,4 The second step and primary goal after stopping significant haemorrhage is to try to reduce the level of contamination and prevent further contam - ination. Contaminated wounds are preferably cleaned within the ‘golden period’. This period of 4–6 hours after wounding is the period in which a contaminated wound can turn into an infected wound because of proliferation of bacteria to more than 105 per gram of tissue.3,4 Tissue invasion by bacteria after this period makes it almost impossible to remove them by irrigation.3,4 Debridement Debridement is indicated whenever necrotic tissue or debris exists in a wound and might impede wound healing. Small amounts of debridement may be feasible without sedation or anaesthesia, but generally anaesthesia is required for aggressive debridement. There are several methods of accomplishing debridement of wounds: surgical, mechanical, autolytic, enzymatic, chemical and biosurgical.2,22 The objective of debridement is to convert the open contaminated wound into a surgically clean wound, which can be closed primarily or secondarily or treated as an open wound if closure is not possible.23 The choice of which method to use depends on the wound and the patient. Important factors to consider are the amount of necrotic tissue, the laxity and elasticity of the surrounding tissue, the presence or absence of a clear demarcation line between necrotic and viable tissue and whether or not the patient can tolerate anaesthesia (11). Because of these variable factors, more than one debridement procedure may be necessary before a healthy wound can be created. Surgical Surgical debridement is used most commonly and involves the surgical removal of necrotic tissue from the wound (12). It is especially important when considering surgical closure of the wound. The goal is to remove all obvious necrotic tissue and debris. However, during the inflammatory phase of wound healing, it is often difficult to distinguish necrotic nonviable tissue from healthy viable tissue because of incomplete tissue demarcation. The assessment of tissue viability, often based on colour and attachment, is subjective and there is a risk of removing healthy tissue.2 The layered approach is often used for surgical debridement.2 This means that superficial devitalized tissue is removed first, followed by the deeper tissues. Nonattached, extremely light or dark tissues should be removed in layers to the level where active bleeding is present. Questionably viable tissue should be left in place and re-evaluated later. The surgeon has to take factors affecting tissue circulation, such as vasoconstriction or vasodilatation, and tissue Wound management: a new protocol for dogs and cats28 11 Debridement of an infected burn wound. 12 Surgical debridement. 11 12 temperature into consideration when using this layered approach.2 En-bloc debridement involves complete excision of the wound and all affected tissue, with a border of normal tissue. This technique should be reserved for wounds that are obviously infected or where layered debridement would not likely result in a healthy wound.2 Mechanical Mechanical debridement is performed using wet-to- dry or dry-to-dry dressings after layered surgical debridement or as the sole means of debridement. In the wet-to-dry technique, a primary dressing of gauzes wetted with isotonic saline, lactated Ringer’s solution (LRS) or 0.05% chlorhexidine diacetate is placed on the wound.2,24 Several layers of wet gauze followed by several layers of dry gauze should be added and covered with an absorptive layer and, finally, an external layer. As the fluid evaporates and the bandage dries, it adheres to the wound surface. When removing the dressing, the adhering tissue is removed at the same time. Wet-to-dry bandages are typically changed daily and used only until healthy granulation tissue starts to appear in the wound. Dry-to-dry dressings work by means of the same principle, but there is no solution added to the dressing. Although these forms of debridement are effective in removing necrotic tissue and the dressings are relatively cheap, they have several disadvantages. Firstly, debridement is nonselective, since both healthy and necrotic tissue adhere to the dressing and are subsequently removed.2,24 The removal of healthy granulation tissue and epithelial cells, as well as wound fluid-containing growth factors and cytokines, combined with the dry environment created, can delay wound healing. Furthermore, the risk of infection is increased and because bandage changes are painful, multiple sedations may be necessary. For these reasons and because newer bandage materials are available nowadays that interact with wound tissues and keep the wound moist, some authors feel that wet- to-dry and dry-to-dry dressings no longer meet the expected standard of care in veterinary medicine.24 Autolytic Autolytic debridement is the most selective method of debridement and it is painless. Autolytic debridement of devitalized tissue is essential to promote wound healing. It depends on the whole area being kept moist so that natural enzymatic reactions can take place. Wound exudate is preserved on the wound surface and natural components, such as enzymes and leucocytes, remove necrotic tissue. Autolytic debridement can be performed with interactive dressings such as hydrogels, hydrocolloids, hydrofibres and foam dressings.2,9,24 Hydrogels are recognized as the standard treatment in human medicine and are considered to be gentle debriders, promoting rehydration of nonviable tissues. Hydrosorb® and Hydrosorb Comfort® are hydrocellular gel dressings made from 60% water and are therefore suitable for keeping granulation tissue and young epithelium moist.25 Another example of autolytic debridement is the use of honey or sugar, which can be applied as a topical medication. Because of its high osmolarity, it attracts fluids and provides a moist environment, which encourages autolytic debridement.26–28 Enzymatic With enzymatic debridement, proteolytic enzymes are applied to the wound to break down the necrotic tissue. It is a very selective method of debridement and is painless. Proteolytic enzymes or derivatives of bacteria (Bacillus subtillis) can be used in wounds with small amounts of necrotic tissue or debris. The enzymes are processed in powders or creams, which can be applied to the wound. The most commonly used enzymes are trypsin, fibrinolysin, chymotrypsin, desoxyribonuclease, papain-urea and collagenase.23 In animal wounds, enzymatic debridement is sometimes used as an adjunct to mechanical and chemical wound debridement, especially in patients with a high anaesthetic risk. Enzymatic agents break down necrotic tissue, yet leave viable tissue intact, provided they stay in contact with the wound for a sufficient time. However, the effectiveness of enzymatic debridement is questionable and a long exposure time is required to remove the nonviable tissue.2,23 Chemical Chemical debridement can be performed with antiseptics such as Dakin’s solution (0.25%solution of sodium hypochlorite), chlorhexidine (bisbiguanide chlorhexidine-diacetate solution, 0.05%), povidone–iodine (1%) and hydrogen peroxide.22 However, it is a nonselective manner of debridement and cells important for wound healing are also damaged. Chemical debridement is not generally recommended. Biosurgical Biosurgical debridement uses the placement of medical maggots (Lucilia sericata) into the wound. The maggots produce enzymes that dissolve the necrotic tissue, but spare healthy tissue, and are therefore selective.2,22 The maggots used for this purpose are specially bred and therefore expensive. Maggots may be indicated for management of deep wounds, which are difficult to debride by other means. Wound management: a new protocol for dogs and cats 29 Wound irrigation and topical medications Wound irrigation Dirty or contaminated wounds can be cleaned by irrigation. Obvious debris, necrotic tissue, dirt and bacteria will be washed away by fluid under pressure. Many fluids have been used for this purpose including tap water, physiological solutions (e.g. isotonic saline, LRS) or antiseptic solutions (e.g. povidone–iodine, chlorhexidine diacetate, sodium hypochlorite). In cases where there is severe contamination, simple initial cleaning with warm tap water can be performed.2 However, tap water has been shown to be toxic to fibroblasts because it may contain cytotoxic trace elements such as fluoride, nitrates, arsenic, cadmium, copper, cyanide, lead, mercury and selenium.8 Furthermore, it has an alkaline pH and is hypotonic. This might result in intracellular diffusion of water molecules, cellular and mitochondrial swelling and, therefore, reduction of oxidative phosphorylation and adenosine triphosphate (ATP) production.8 However, the use of tap water has never been proven to either delay wound healing or increase the risk of wound infection.29,30 The irrigation pressure should not be too high because it may damage tissue and push contamination further into the wound. Specialized equipment, which produces a pulsating stream of water with a pressure of about 0.6 kg/cm2 (8 psi), is available.4 This pressure can also be achieved by using a 19 gauge needle and a syringe of at least 30 ml (13).4 In minimal to moderately contaminated wounds, cleaning should preferably be performed using isotonic saline or LRS. In selected patients, dilute antiseptic solutions such as 0.05% chlorhexidine or 1% povidone–iodine solution can be used. Saline and LRS can remove bacteria and foreign matter mechanically, are isotonic and should be used in a sterile form. They can be used safely in any situation, but are not bacteriostatic.2 They are used widely with good results in wounds that are not highly contaminated. Because the physical aspect of wound cleansing is the most important function of irrigation, the use of antiseptic solutions may not be necessary. However, antiseptic solutions used in the concentrations mentioned above aid in decreasing bacterial contamination without resulting in substantial damage to the exposed tissues.31 Topical antibiotics and antiseptics When dealing with infected wounds, the use of systemic antibiotics is preferred in order to prevent the toxic effects on cells important for wound healing that occur after topical administration. However, for a systemically given antibiotic to reach the wound area, a good blood supply is Wound management: a new protocol for dogs and cats30 needed. In general, the use of antibiotics should be minimized to prevent the development of bacterial resistance and they should be used only for infected wounds.32 When necessary, broad-spectrum antibiotics are given for 5–7 days, preferably based on the results of a bacteriological culture and antibiogram (14). Pending the results of culture and sensitivity, the initial antimicrobial therapy can be guided by a Gram stain.2 The use of topical antibiotics and antiseptics is controversial. They are used to prevent or treat wound infections and to increase the rate of healing, but research, especially in vitro, has shown that the use of medications on wound healing may have an adverse effect.2,31,33,34 Topical antibiotics should promote normal healing by protecting the wound from infection. However, topical antibiotics have no effect on dead tissue, haematomas or proteolytic enzymes causing necrosis. Infection results from bacterial invasion of open lymphatics and blood vessels. Haemostatic mechanisms seal the bacterial infiltrates in deeper tissue. Pathogenic bacteria can replicate and overwhelm local host defences, resulting in infection. Antibacterial agents must be present in sufficient quantities at the time of bacterial invasion or within 1 hour to assist the host defences in eliminating these pathogens.16,22,33 Topical and systemic antibiotics have no beneficial effect once infection is established. The presence of wound coagulum prevents antibiotics from reaching effective levels in deep tissues and prevents systemic antibiotics from reaching superficial bacteria. The effectiveness of topical and systemic antibiotics may be extended to 24 hours with gentle cleansing of the contaminated wound.16,22,33 Use of antibiotics should never replace surgical, mechanical or enzymatic debridement, but should be used in combination with these procedures. Topical antibiotic selection should be based on the following considerations: spectrum of activity, dose, pharmacokinetics, tissue and systemic toxicity, timing, route of administration and type of preparation (i.e. lavage, ointment, cream or powder).16,22,33 The topical antibiotic selection should be broad spectrum, bactericidal and have a low risk of toxic or allergic reactions. Indications include wounds older than 4 hours, marked soft tissue injury or bacteria present after debridement. Antibiotics should be administered at initial presentation and be continued until 5 days after wound closure or development of a healthy granulation tissue bed. The advantages of antibiotics over antiseptics include selective bacterial toxicity, effectiveness in the presence of organic matter and combined efficacy with systemic antibacterial therapy.16,22,33 The disadvantages include expense, reduced antimicrobial spectrum, potential for bacterial resistance, creation of superinfections and increased risk of nosocomial infections. In addition, epithelialization may be delayed by topical antimicrobials that have a petroleum base. In-vitro studies have shown that topical antimicrobials administered at bactericidal concentrations are either cytotoxic or impair local cell function. Commonly used topical antibiotics are gentamicin, nitrofurazone, cephalosporins, mafenide, triple antibiotic ointment (TAO), silver sulfadiazine (SSD) and tris-ethylenediamine tetra- acetic acid (EDTA).22 The general advantages of antiseptics such as iodine compounds, chlorhexidine and hypochlorite (Dakin’s) solutions over topical antibiotics are the broader spectrum of activity against bacteria and other microorganisms and fewer problems with bacterial resistance.16,22,33 However, they are often less powerful when a specific infection has to be treated or prevented.16,22,33 Antiseptics should preferably be applied to intact skin, since application on open wounds can result in severe tissue inflammation, which decreases resistance to infection, wound strength, granulation tissue formation, contractile ability and rate of epithelialization. Furthermore, they increase the intensity and duration of inflammation and are toxic to human keratinocytes and fibroblasts.32 Gentamicin Gentamicin has efficacy against gram-negative bacteria and Staphylococcus spp. It has been used as a topical antibiotic rather than a systemic one because of the toxicity risks associated with the latter. Wounds treated with 0.1% gentamicin solution or cream have been shown to be effective in controlling bacterial growth, with no negative effects on wound contraction and epithelialization.35,36 However, isotonicgentamicin solutions are preferred as they do not inhibit wound contraction and even promote epithelialization.10 Nitrofurazone Nitrofurazone has a broad gram-positive spectrum and also hydrophilic properties because of its polyethylene base. Water is drawn into the wound and the viscous exudate becomes thinner and more diluted, making it less toxic and easier to absorb into bandages. However, it may have a negative impact on epithelialization.10,22 Cephalosporins Cefazolin is characterized by a broad gram-positive spectrum of activity and efficacy against some gram-negative organisms. Topically administered cefazolin is highly bioavailable, reaches high concentrations in the wound fluid and is rapidly absorbed.10 In one study, patients treated for Staphylococcus aureus infections by wound irrigation demonstrated concentrations of cefazolin in wound fluid well above the miminum inhibitory concentrations, which remained high for 24 hours.37 Wound management: a new protocol for dogs and cats 31 13 Irrigation of a contaminated wound using a syringe and needle. 14 Taking a swab from a contaminated wound for culture and sensitivity testing. 13 14 Mafenide Mafenide (hydrochloride or acetate) is a topical sulpha compound, available as an aqueous spray, with a wide spectrum activity against gram-negative bacteria. Because mafenide is active against Pseudomonas and Clostridium spp. and methicillin- resistant Staphylococcus aureus (MRSA), it is particularly useful for severely contaminated, chronic wounds.10 It has been used mainly for the treatment of burn wounds in humans, but allergic reactions (contact and/or irritant dermatitis) have been reported.38 Triple antibiotic ointment TAO (neomycin, polymyxin B and bacitracin in a petrolatum base) is a safe and effective topical agent used mainly for the prevention of skin and wound infections. It is effective against many pathogenic bacteria, but usually not against Pseudomonas spp. Resistance to TAO does not develop readily and complications and adverse reactions are rare.39 Because of its zinc content it may stimulate epithelialization.10,22 Silver compounds The best known silver compound antibiotic used in wound dressings is SSD cream. SSD is a combination of silver and the antibiotic sulfadiazine. It is most commonly used in wound dressings for burn treatment in humans, because of the broad-spectrum action against pathogens (especially against Pseudomonas spp.).22,32,33 Silver is also used as an antimicrobiological component of modern wound dressings in other patients. However, side-effects, including allergic reactions, silver staining of the wound, hyperosmolality, methaemoglobinaemia and haemolysis, have been reported.40,41 To date there is insufficient evidence to establish whether silver-containing dressings promote wound healing or prevent wound infection.41 Iodine compounds Two types of iodine formulations are available, povidone–iodine and cadexomer iodine. The active component against microorganisms of both these products is free iodine, which has a broad antimicrobial spectrum against gram-positive and gram-negative bacteria, viruses, fungi and protozoa.31,33,42 Povidone–iodine solution (0.1–1.0%) is recommended as it is rapidly bactericidal, but not cytotoxic, to cells responsible for wound healing.43 A disadvantage of the use of iodine is inactivation by organic matter, which is always present in open wounds; however, there is no known bacterial resistance. Residual activity lasts only 4–8 hours, therefore frequent reapplication of dressings is required. Iodine absorption from the wound may cause excess systemic iodine concentrations and transient thyroid dysfunction. The low pH of the solution can cause or intensify metabolic acidosis and contact hypersensitivities may occur in as many as 50% of dogs scrubbed with povidone–iodine.10 In a 0.5% concentration, povidone–iodine is cytotoxic to fibroblasts.10 While some in-vitro studies have shown impairment of wound healing, others have demonstrated improvement of wound healing when povidone–iodine is used. However, the relevance of these data for in-vivo conditions is questionable.44 The cadexomer iodine products are newer, less toxic and have been found to be beneficial to wound healing.33 Chlorhexidine solution Chlorhexidine digluconate is frequently used for wound lavage, but other solutions, including chlorhexidine diacetate and chlorhexidine dihydrochloride, have been used. Chlorhexidine digluconate has a wide spectrum of activity against gram-positive and gram-negative bacteria, but a variable and inconsistent efficacy against viruses and fungi. Chlorhexidine binds to the protein of the stratum corneum of the skin, creating a persistent residue that lasts for a few hours.36,45,46 The bactericidal activity of chlorhexidine has been reported to be significantly higher than the activity of povidone–iodine in vivo.47 Chlorhexidine has a low toxicity when used as a skin cleanser or as an aqueous solution for wound asepsis.45,48 Even though it may be toxic for fibroblasts in vitro, rinsing with diluted chlorhexidine (0.05%) has no negative effect on wound healing. However, when used intra-articularly, this concentration may cause synovial ulceration, inflammation and fibrin accumulation.45 For wound irrigation a 0.02% solution is recommended, but a less diluted 0.05% solution can probably be used safely in dressings.48 Prontosan Prontosan is a wound irrigation solution containing polyhexanide, a polymeric biguanide and cationic preservative. It inhibits the growth of micro - organisms and aids in the removal of dirt and debris from chronic wounds.49,50,51 It is commonly used as an antiseptic in chronic wounds and burn wounds in people, but to date there are no studies of its use in companion animals. It has less toxicity on primary human fibroblasts and keratinocytes than other topical antiseptics.49 However, commercially available wound dressing products can reduce the antibacterial efficacy of poly hexanide.50 This is most likely due to poly hexanide’s strong cationic character and, therefore, its limited compatibility with the anionic matrices that can be present in certain wound dressing materials.50 Wound management: a new protocol for dogs and cats32 Dakin’s solution Dakin’s solution (sodium hypochlorite 0.5%) is bactericidal to the organisms commonly present in open wounds. It releases free chlorine and oxygen into tissues, killing bacteria and liquefying necrotic tissue.10 It is detrimental to neutrophils, fibroblasts and endothelial cells and therefore most authors do not recommend the use of Dakin’s solution in open wounds.10 However, there is a renewed interest in its use nowadays because of its aggressive debridement activity and its broad-spectrum activity against microorganisms.48 When used, it is indicated only for severely contaminated or infected wounds and only early in the debridement phase of wound healing. A 0.005% solution is recommended in these cases to prevent cytotoxic effects on the cells responsible for wound healing.16,31 Tris-ethylenediamine tetra-acetic acid Tris-EDTA added to lavage solutions increases the permeability of gram-negative bacteria to extracellular solutes, making them more susceptible to destruction by lysozymes, antiseptics and antibiotics.10,22,52 Tris-EDTA solution can be prepared by adding 0.5 g of EDTA and 6.05 g of tris to 1 litre of sterile water. Sodium hydroxide is used to adjust the pH of the solution to pH 8, after which the solution can be mixed and autoclaved for 15 minutes.10 Tris-EDTA in sterile water rapidly lyses Pseudomonas aeruginosa, Escherichia coli and Proteus vulgaris.10,22 The addition of tris-EDTA to chlorhexidine gluconate solution increases antimicrobial effectiveness and, similarly, tris-EDTA has a synergistic activity against bacteria when combined with topical antibiotics.10,22,52 Glycerol Glycerol (also known as glycerin) is a trihydroxy alcohol usually obtained by saponification of lipids.53In medicine, glycerol has been used in the treatment of brain oedema, as a laxative and in cough syrups, throat lozenges and suppositories. The beneficial effects of the chemical on the skin have been recognized for a long time and include improvement of stratum corneum hydration, skin barrier function and skin mechanical properties, as well as acceleration of wound healing processes.53 Impairment of the epidermal cell proliferation related to reduced epidermal glycerol content and ATP was demonstrated in AQP3 null mice. Glycerol supplementation resulted in correction of the defective epidermal cell proliferation and enhanced wound healing rates.53 Antimicrobial effects have also been attributed to glycerol. An antimicrobial effect, more pronounced at 36°C (96.8°F) than at 4°C (39.2°F), has been demonstrated. Gram- negative species were found to be more susceptible to glycerol than the gram-positive ones.53,54 Because of its antimicrobial effects, while providing an excellent moisturized wound healing environment, glycerol is currently one of the most commonly used topical medications used in dressings for wounds in the repair phase of wound healing in the authors’ hospital. Honey Honey has been used in wound management for centuries, but was partly forgotten by modern medicine in the last century. Because of the growing desire to use more natural products and problems associated with bacterial resistance, a renewed interest has taken place in the therapeutic use of honey in wound management in both human and veterinary medicine. Recent research has shown that using honey can significantly reduce the total healing time.55,56 The functions and mechanisms of the action of honey on a wound are summarized in Table 1. Honey exerts antimicrobial activity because of its high osmolarity and low pH. A low pH favours repair of wounds. Honey contains inhibin, an enzyme that generates hydrogen peroxide, and glucolactone and/or gluconic acid, which act as a mild disinfectant and mild antibiotic, respectively. Honey also provides antioxidants, which protect wound tissues from damage imparted by free oxygen radicals.34,57,58 Wound management: a new protocol for dogs and cats 33 Table 1. Functions of honey. • Antimicrobial activity. • Anti-inflammatory activity. • Decrease oedema. • Neutralize odours. • Stimulate granulation. • Stimulate epithelialization. • Source of nutrition. Honey stimulates the processes of granulation and epithelialization because of the improved nutrition of cells important to wound healing, the creation of a moist environment and because hydrogen peroxide promotes angiogenesis, growth of fibroblasts and the mobilization and activation of epithelial cells.26,57,59,60 Debridement is also stimulated by the osmotic effect and the moist environment. When necrotic tissue is present, however, surgical debridement is advised before application of honey. Honey used for treatment of wounds should be sterile, as nonsterile honey can contain Clostridium botulinum spores, which can cause botulism.56,60 Sterilization must be done with gamma irradiation because heat will destroy the enzymes and, consequently, the antimicrobial activity of honey.34,56,60 Honey has no reported toxic side-effects and is nonadherent to the wound surface. (Note: Application on open wounds is known to be painful in humans.) Its use would be specifically indicated in the treatment of wounds infected with bacteria resistant to antibiotics and in chronic nonhealing wounds (15).60–62 An occlusive or absorbent secondary dressing is needed to prevent leakage of the honey. Honey does not diminish wound exudate and initially dressings have to be changed at least daily. Once a healthy granulation tissue bed is present and epithelialization has begun, application of honey dressings may be ceased.34 Honey is a natural product and any effect could be influenced by the species of bee, the flowers used, geographic location or processing and storage conditions.34,56,60 In addition, even though inhibition of bacterial growth has been demon - strated in vitro, the scientific merit of studies suggesting increased wound healing has been questioned.34 Sugar Sugar has a similar hyperosmolarity-induced antimicrobial effect to honey and it has also been used in wound management.26,27 Since the antimicrobial actions of sugar depend on its concentration, this effect will be lost when sugar is used in highly productive wounds.27 This problem can partly be prevented by multiple (3–4 times daily) bandage changes along with thorough lavage of the wound in the first 24–48 hours. Bandage changes can become less frequent when undissolved sugar remains in the wound.34 Sugar also provides nutrients, has a deodorizing action and stimulates granulation and epithelialization.27 There are no known adverse effects of sugar on wound healing, but application of sugar on a wound is reported to be painful in humans.27 Sugar treatment should be replaced by treatment with a (semi-)occlusive dressing, such as hydrogel or hydrocolloid, after the formation of a healthy granulation bed.22,27 Maltodextrin Maltodextrin (a D-glucose polysaccharide) is available in a hydrophilic powder or gel form containing 1% ascorbic acid. It is used as a wound- healing stimulant on contaminated and infected wounds.10 It is reported to stimulate healing by supplying glucose for cell metabolism via hydrolysis of its polysaccharide component.10 Its hydrophilic property draws fluid through the tissue, keeping it moist. Maltodextrin causes chemotaxis of neutrophils, lymphocytes and macrophages into the wound. In addition to reducing odour, exudate, swelling and infection, it may enhance early granulation tissue formation and epithelial growth.10,34,63 Maltodextrin also has antibacterial and bacteriostatic properties.63 After debridement and lavage, a 5–10 mm layer of maltodextrin is applied to the wound. It should then be covered with a nonadherent primary bandage followed by absorbent wrap and outer tertiary bandage layer, and changed daily.63 It can be used from the early inflammatory stage to the repair stage of healing.10 Tripeptide-copper complex Tripeptide-copper complex (TCC), a hydrogel with chemoattractant properties for mast cells as well Wound management: a new protocol for dogs and cats34 15 Application of a honey-based ointment to a chronic nonhealing wound on the limb. 15 as monocytes and macrophages, stimulates several biological activities during acute wound healing.22,34,63 It is thought to increase angiogenesis, collagen deposition, epithelialization and wound proteases, ultimately improving the wound environment.34,63 In dogs, TCC has been shown to advance open wound healing, mainly stimulating granulation tissue formation, especially during the first 7 days.12,63 The median time for coverage of the wound with granulation tissue was significantly shorter using TCC in rabbits compared with a control group.64 Topical TCC has also been shown in a recent study to be an effective stimulant of healing of ischaemic open wounds in rats.65 TCC is applied to the wound after debridement and lavage, starting in the late inflammatory phase and continuing through the proliferative phase. A nonadherent primary bandage pad should then be placed over the wound, followed by a secondary absorptive layer and a tertiary outer layer, which need to be changed daily.22,63 Zinc Zinc is an essential trace element in the body and serves as a cofactor in numerous transcription factors and enzyme systems, including zinc- dependent MMPs, that augment autodebridement and keratinocyte migration during wound repair.66 Zinc deficiency of hereditary or dietary cause can lead to delayed wound healing. Oral zinc supplementation may be beneficial in some human patients; however, topical administration appears to be superior. This is due to its action in reducing superinfections and necrotic material (autodebridement) via enhanced local defence systems and collagenolytic activity, inaddition to the sustained release of zinc ions, which stimulate epithelialization of wounds.66 Studies have shown unequivocally that topical zinc therapy reduces wound debris and advances epithelialization in surgical wounds in the rat.66,67 Median healing times and the occurrence of S. aureus in wounds both decreased compared with a placebo group in humans.68 Zinc oxide has also been shown to enhance wound contraction in rabbits, but studies of its use and toxicity in dogs and cats are not available.64 Aloe vera Aloe vera gel is extracted from the mucilaginous zone of the aloe vera leaf and it contains 75 potentially active constituents.10,34,69 Aloe vera has anti-inflammatory effects, antifungal activity and an antibacterial activity against P. aeruginosa.10 It enhances contraction of wounds and increases breaking strength through increased collagen activity. It stimulates fibroblast replication and has antiprostaglandin activity against thromboxane A, which is produced in burnt dermal tissue and pressure sores.69 Aloe vera gel has therefore been used extensively in human burn wounds. Cumulative evidence tends to support the view that aloe vera might be an effective intervention in wound healing for first- and second-degree burns.70 A recent study performed in rats showed a significant decrease in wound diameter and increased healing rate of created wounds after application of aloe vera gel compared with a control group.71 Aloe vera reportedly also has analgesic activity due to the presence of a salicylate-like substance.69 Indeed, application of aloe vera cream on the surgical site was proven to be effective in reducing postoperative pain, healing time and analgesic requirements in patients compared with a placebo group.72 However, further well-designed trials with sufficient details of the contents of aloe vera products should be carried out to determine the effectiveness of aloe vera in wound healing before its use can actively be recommended in dogs and cats. Acemannan Acemannan is a derivate of the aloe vera plant and is available as a hydrogel or as a foam.10,22 It acts as a growth factor, stimulating macrophages to enhance IL-1, which stimulates fibroblast proliferation, and TNF-! secretion, which stimulates angiogenesis, epidermal growth and motility, and collagen deposition.34,63 In a topical gel form, it enhanced contraction and epithelialization of paw wounds in dogs and stimulated granulation tissue formation over exposed bone.8,63 A recent study in rats demonstrated that acemannan significantly enhanced oral wound healing via the induction of fibroblast proliferation and stimulation of keratinocyte growth factor-1, VEGF and type I collagen production.73 However, another study failed to demonstrate any significant advantage of acemannan dressings over moist saline gauze dressings for the treatment of pressure ulcers.74 As with aloe vera, application is indicated after debridement and lavage of the wound, from the inflammatory phase until the end of the proliferation phase.63 Bandages should be changed daily. Live yeast cell extracts Live yeast cell derivative is a water-soluble extract from brewer’s yeast.34 It is reported to contain substances that increase wound oxygen consumption, angiogenesis, epithelialization and collagen synthesis.34,47 In horses it has been suggested that live yeast cell extracts prolong healing time by delaying epithelialization and inhibiting contraction, while favouring the Wound management: a new protocol for dogs and cats 35 formation of exuberant granulation tissue.34 In a study on wound healing in diabetic mice, it was clearly demonstrated that live yeast cell extracts improve the formation of granulation tissue, epithelial migration and wound closure.75 Although prospective studies in dogs or cats are lacking, one experienced researcher states that he believes live yeast cell extracts do enhance epithelialization in dogs.36 Growth factors For more than 20 years, clinical trials have been conducted on the application of topical exogenous recombinant growth factors to accelerate the healing of chronic wounds. The results have been conflicting.76 Some trials have been encouraging, but most have been somewhat disappointing.15,76 To date only one recombinant growth factor, PDGF, has been approved by the US Food and Drug Administration, and it is for use in diabetic foot ulcers in humans only.11,15,16 However, a single growth factor will not be able to resolve all issues of repair or strengthen all vulnerabilities of chronic wounds and although not yet commercially available, other growth factors are currently undergoing investigation as an adjunctive treatment for nonhealing wounds in humans. These include TGF-#, FGF, VEGF, keratinocyte growth factor, EGF, IGF and others such as platelet activating factor, growth hormone, thrombin, colony- stimulating factors, L-arginine and MMPs. Their use in the treatment of chronic wounds in veterinary patients warrants further study before they can be recommended. PDGF is released from the alpha granules of platelets and is responsible for the production of TGF-#. A recombinant PDGF product, becaplermin gel, is commercially available.11 It is strongly chemotactic for monocytes, neutrophils, fibroblasts and smooth muscle cells. It also has mitogenic properties, promoting the mitosis of fibroblasts, endothelial cells and smooth muscle cells. It was shown to stimulate angiogenesis, wound contraction, granulation tissue formation and wound remodelling in experimental rabbit and rat studies.3,8 When used in phase III trials in people with diabetic foot ulcers, PDGF gave a persistent 10% overall increase in the rate of complete healing.11,15 Another growth factor that has been tested extensively for use in diabetic and pressure-related ulcers is TGF-#. It is derived from platelets and numerous other cells involved in wound healing. It has a powerful mitogenic effect on macrophages, smooth muscle cells and osteoblasts. Like PDGF, it stimulates angiogenesis and fibroplasia as well as keratinocyte migration, but has an inhibitory effect on the production of MMPs, keratinocyte proliferation, endothelial cell growth, lymphocytes and epithelial cells.3,8 TGF-# has been shown to increase granulation tissue and collagen formation as well as wound tensile strength when applied locally in some animal models of normal or impaired healing; however, in limb wounds in horses, no beneficial effects were noted.34 Platelet-derived products offer an advantage over individual cytokines or growth factors, because a large number of mediators are easily available in high concentrations when platelets are activated. Degranulating platelets release growth factors and many wound healing mediators. Topical application of growth factors derived from platelets encouraged repair of previously nonhealing wounds in human patients. Accelerated epithelial differentiation and more mature granulation tissue formation were found in wounds of the distal limb of horses when treated with a platelet-derived wound healing gel.34,77 Wound closure One of the most important decisions to make during wound management is whether or not a wound should be surgically closed and, if so, when. Wounds that are left to heal through the formation of granulation tissue, contraction and epithelialization because of severe infection or being too large to close primarily, constitute healing by second intention (secondary wound healing or healing per secundam). Second intention healing can be very effective; however, the healing time can be very long and can be complicated in areas of the body with high motility, and excessive contraction and scar tissue formation can lead to wound contracture. Primary wound healing (wound healing per primam) is obtained through direct adhesion of the wound edges (after primary closure using sutures, staples or glue) directly after injury and before or after granulation tissue formation (delayed primary and secondary closure, respectively).Primary closure Primary wound closure is defined as direct closure of the wound after lavage and debridement. Primary wound closure is indicated and preferred for clean wounds, including surgical wounds and contaminated wounds that have been debrided and are less than 6 hours old.3,4 The wound healing process is in principle the same as with the open wounds described earlier, but all the phases are much shorter and many of them are not visible. Primary closure leads to a more rapid anatomical and functional recovery than delayed and secondary closure (16). Wound management: a new protocol for dogs and cats36 • Passive drains are easier to insert and cost less than active drains. The most commonly used passive drain is the Penrose drain, a soft latex tube. Passive drains have to be placed in the most dependent part of the wound in order to allow fluid to drain from the wound under gravity. The drain should be secured to the skin with sutures proximally and distally or dorsally and ventrally. One of the disadvantages of passive drains is the risk of ascending infection, especially when the drain is left in place for several days or is left uncovered. It is therefore recommended that the drain is covered with a sterile dressing to minimize this risk, prevent leakage of the fluid into the environment and allow for assessment of the quantity of fluid that has been produced.3 Another disadvantage of passive drains is that it is not possible to place a drain in every area of the body because of its dependency on gravity.3 An Elizabethan collar should be used to prevent the patient from removing the drain, especially when a dressing is not used. Wound management: a new protocol for dogs and cats 37 After the golden period of 4–6 hours, primary closure will become less desirable because of the increased chance of wound infection.3 If the level of contamination, tissue viability, depth of tissue damage or vascular supply is questionable, other options should be considered.2 With uncomplicated healing after primary closure of a wound, the sutures can generally be removed in 7–10 days in dogs.4 Delayed primary closure Delayed primary closure is defined as a wound that is not closed immediately, but is managed as an open wound until it is clean and without formation of granulation tissue.10 Closure is therefore usually performed within 3–5 days after the emergence of the wound. Delayed closure allows for drainage of the wound, a decrease in contamination and the development of a clear demarcation line between viable and necrotic tissue prior to surgery. Secondary closure Secondary closure is defined as closure of the wound after the formation of granulation tissue and is most commonly used for contaminated or infected wounds. There are two methods of secondary closure:2–4 (1) leaving the existing granulation tissue intact and separating the edge of the skin from the granulation tissue bed and advancing the skin over the granulation bed; and (2) excision of the granulation tissue bed followed by primary closure. The second method is usually the preferred method because the wound edges are more mobile for closure, cosmetic results are better and the incidence of infection is lower.3 Important factors in choosing between the two methods are the thickness and health of the granulation tissue bed and the mobility of the skin edges.2 The total healing time is still reduced when compared with healing by second intention. Drainage Dead space can result when suturing a large wound. Fluid accumulation in these spaces is a good medium for growth of bacteria. Drains can be placed to prevent accumulation of fluids. For minimally contaminated wounds with minimal dead space formation, surgical debridement, lavage and primary closure usually suffices, and drainage is often not necessary. In moderately contaminated wounds or where there is a large dead space, drainage is recommended. For grossly contaminated and infected wounds, delayed primary or secondary closure is recommended.3 The most common types of drains used are passive and active drains: 16 Well-healed wound after primary closure. 16 • Active drains work by creating a vacuum through the drain. This vacuum will remove the fluid from the wound by suction, thus eliminating the need for gravity. Therefore, this type of drain can be placed anywhere on the body. An additional advantage is the reduced risk of infection. The use of active drains is slightly more elaborate than that of passive drains, since the containers in which the wound fluid accumulates will need to be emptied regularly (17). Wound dressings and bandages Dressings refer to materials that are applied directly to the surface of a wound; bandages are wraps primarily used to hold plain and medicated dressings in place. Other functions of bandages are support or immobilization of body parts, applying pressure to control haemorrhage, obliteration of dead space or cavities and protection of a wound from external trauma and contamination. Bandages consist of three defined layers: a primary layer (contact dressing), a secondary or intermediate (absorptive) layer, and a tertiary or outer (protective) layer.3,8,10,24,63 The functions of wound dressings are detailed in Table 2. The most important function is to allow for moist wound healing. Wounds that are kept in a moist environment have a reduced total healing time because of preservation of the voltage gradient.24 During the proliferation phase of wound healing, this gradient will stimulate the formation of granulation tissue and epithelialization. Growth factors are kept on the wound, leucocytes are not trapped in a scab and are functional, and the mildly acidic pH and warm temperature are optimal for wound healing. The moist environment also prevents trauma due to adherence of the dressings. In addition, autolytic debridement takes place in a moist environment by maintaining exudate with enzymes at the wound surface.24 The primary or contact layer of the dressing can be adherent or nonadherent and occlusive, semi- occlusive or nonocclusive.3,8,10,24 In general, an adherent contact layer is used when wound debridement is required, whereas a nonadherent contact layer is selected when granulation tissue has formed. Occlusive dressings are impermeable to air and fluid and are used on low exudative wounds to maintain a moist environment. Semi-occlusive dressings allow air to penetrate and exudate to escape from the wound surface. The modern, most commonly used nonadherent (semi-) occlusive moisture-retentive dressings provide the desired moist environment for wound healing. They are also known as interactive dressings. Dressings belonging to this group include hydrocolloids, hydrogels, hydrofibres, alginates, foams and polyethylene glycol dressings. The traditional gauzes are considered to be passive dressings and can be used both dry as an adherent or wet as a nonadherent dressing. In contrast to the synthetic dressings, biological dressings are derived from natural sources such as porcine submucosa or equine amnion. They may have similar pro - perties to the dressings discussed above. Finally, topical medications can be added to a dressing (see Topical antibiotics and antiseptics) to create an antimicrobial dressing. Table 3 provides an overview of this classification of wound dressings. The most important point to remember when choosing a dressing is that there is no single dressing that is perfect for all wounds in all phases of wound healing. Every wound requires initial and follow-up assessments to assess whether wound dressing changes are required. Nonocclusive dressings Gauzes are nonocclusive dressings and are available in adherent and nonadherent forms as well as in sterile and nonsterile forms.3,10 Because they are relatively inexpensive, they are commonly used in veterinary medicine and especially in wet-to-dry bandages during the debridement phase. They are not recommended in more mature wounds because changing a dried dressingwill disrupt granulation tissue.24 Because they dry easily after application to the wound, it is important to keep the dressings wet in order to provide a moist wound environment when used on more mature wounds. This requires changing the dressing every 8–12 hours. A secondary absorptive layer and a tertiary protective Wound management: a new protocol for dogs and cats38 17 Closed suction (active) drains inserted after surgery. 17 layer are required to prevent migration of bacteria from the environment through the pores of the dressing. The use of gauze is recommended in acute, nondebrided wounds that have to be inspected and irrigated regularly. Modern dressings are only cost-effective when they are changed daily or less frequently.24 They are therefore not recommended when there is still a considerable chance of infection because this requires more regular inspection and cleaning. Gauzes can be impregnated with different types of fluids and topical medication. Hypertonic saline dressings, for example, can be used in the early phases of wound healing because of their bactericidal mechanism and debridement properties by attracting fluid and debris from the wound. In contaminated or infected wounds, gauzes can be impregnated with antimicrobials. Moisture-retentive dressings Moisture-retentive dressings can be divided into occlusive and semi-occlusive dressings.10,24 Whereas occlusive dressings are impermeable to water and water vapours, semi-occlusive dressings are impermeable only to water, allowing a certain amount of moisture to be lost as vapour. Both types of dressings protect the wound against external contamination and excessive drying, and in addition, semi-occlusive dressings prevent wetting and maceration of the wound. The same dressing can be considered to function as both an occlusive and a semi-occlusive dressing, depending on the moisture vapour transmission rates, which are influenced by the secondary and tertiary bandage layers.78 When choosing an occlusive dressing, particular attention must be paid to the skin surrounding the wound. Because of the moist environment, the risk of maceration of the skin is greater. To prevent maceration, the dressing can be cut to the size of the wound and the wound edges can be protected with zinc oxide. Another aspect to take into consid - eration is the amount of granulation tissue that is formed, because excessive granulation tissue formation is possible when using occlusive dressings.79 It is generally recommended to change to semi-occlusive dressings when hypergranulation is observed or expected.79,80 An advantage of occlusive dressings over semi- occlusive dressings is greater stimulation of re-epithelialization.79 They are therefore generally recommended in noninfected partial-thickness or advanced granulating wounds. A disadvantage of occlusive dressings is that no oxygen, important for collagen synthesis, can reach the wound from the environment.47 However, low oxygen tension also stimulates angiogenesis.81 Infection rates are low with occlusive dressings because the natural substances that inhibit bacterial growth accumulate in the wound fluid and wounds are protected against environmental contamination.24 When removing a (semi-)occlusive dressing, it can have a purulent appearance and foul odour.22,24 This should not be mistaken for infection. Wound management: a new protocol for dogs and cats 39 Table 3. Overview of wound dressings. Interactive dressings Passive dressings • Hydrocolloid. • Gauzes: • Hydrogel. ° Adherent. • Hydrofibre. ° Nonadherent. • Foam. • (Silver) alginate. • Polyurethane film. Biological dressings • Bovine collagen. • Equine amnion. • Porcine small intestinal submucosa. Table 2. General functions of wound dressings. • Provide a moist environment. • Provide a warm environment. • Protect from trauma. • Protect from external contamination. • Application of topical medication. • Immobilization of the wound. • Support of the wound edges. • Absorb exudate. • Prevent or reduce oedema. • Provide an aesthetic appearance. expensive. Used during the proliferation phase, hydrogels may cause formation of exuberant granulation tissue.79 They can also be used to rehydrate a wound by applying the hydrogel together with fluid onto the wound. Hydrofibres Hydrofibres are composed of sodium carboxy- methylcellulose. A gel is formed when there is contact with wound exudate and a moist wound environment is created. Hydrofibres can absorb large amounts of wound fluid and are therefore indicated in moderate to heavily exudating wounds.3,8,24 There are two different applications of hydrofibres: dry and wet. When used wet, they are placed on the wound together with fluid and replaced before the dressing dries. If used dry, the dressing is allowed to form a scab on the wound surface, which will loosen when the wound surface heals. Alginates Alginate dressings are derived from seaweed and contain calcium ions. Calcium ions are important for haemostasis and therefore these dressings can be used in mildly bleeding wounds. They form a moist gel by exchanging sodium from wound fluid and calcium ions from the alginate dressing.22 Alginates generally have good absorptive properties. They can be used for highly exudative and infected wounds (i.e. in the early stages of wound healing). Bacteria will become trapped in the alginate gel, thereby decreasing the risk of infection.24 They are not indicated in minimally exudative wounds because this might result in dehydration of the wound.24 Foam dressings Most foam dressings are made of polyurethane and they are available as sheets and as cavity dressings. The absorptive capacity and water vapour permeability differ between foams, but are generally good. In-situ foams can be used for the treatment of large cavity wounds and they then prevent premature closure of the wound.24,83 Foam dressings keep the wound environment moist, thereby promoting wound healing, and they are indicated in the inflammatory as well as in the proliferative phase of healing.9 They can also be used to deliver fluid for rehydration or medications. Polyurethane films A polyurethane film is a thin film that can be used as a semi-occlusive layer to create a moist environment. Water and bacteria cannot permeate the film, but water vapour can escape. Autolytic Wound management: a new protocol for dogs and cats40 Hydrocolloids Hydrocolloids are dressings that stimulate wound healing by providing a moist environment. They are interactive dressings that change into a gel when absorbing fluid and maintain a moist and warm environment for optimal wound healing. The amount of exudate that can be absorbed by the dressing varies depending on the individual product, but it is often low to moderate.24,78 To prevent maceration of the surrounding skin, the dressing should be cut to the shape of the wound. Hydrocolloid dressings are nonadherent to the wound surface, but most have an adhesive border to attach the dressing to healthy skin. Many of the dressings are impermeable to water as well as to water vapour and are thus occlusive.24 This protects the wound against external contamination and excessive drying. A secondary layer and a tertiary layer complete the bandage, which has to be changed every 2–4 days. Most research on hydrocolloid dressings is derived from humans, but a study has recently been performed on dogs.82 The dressings appeared to be easy to use, adhesed well and the wounds healed better than untreated wounds. The granulation tissue was more regularly organized and the number of inflammatory cells had decreased. This research also concluded that the adhesives used in the dressings were strong and suitable for animal use. A disadvantage of strong adhesiveness is that wound contraction is inhibited because the adhesive bandage counteracts the forces of wound contraction.17 Hydrocolloids are indicated in the proliferation phase of wound healing, but hypergranulation must be monitored.22,79They also have a place in the debridement phase by creating an environment for autolytic debridement.22 However, the costs and benefits should be considered. Hydrogels Hydrogels work on the same principle as hydrocolloids (i.e. they are nonadherent, occlusive and provide a moist environment). They are placed on the wound as a gel or as a composite sheet consisting of a gel adhered to the sheet. The sheets have to be cut to the shape of the wound to prevent maceration of the surrounding skin. The amount of exudate that can be absorbed by the dressing again depends on the individual product, but is often very low.22,24 Dressings are normally changed every 3–4 days. Hydrogels are indicated in wounds free of infection and excessive necrotic tissue. They can be used in the debridement phase by creating an environment for autolytic debridement, but are debridement is possible under a polyurethane film.24 The absorptive capacity is minimal, therefore polyurethane films should be used for dry to minimally exudative wounds. They can also be used as an occlusive layer over other dressings.24 Petrolatum-impregnated gauzes Nonadherent gauzes include petrolatum- impregnated gauzes. The absorptive capacity of these semi-occlusive dressings is low and fluid can move through pores in the dressing.24 Therefore, they should be covered with secondary and tertiary bandage layers. (Note: Water can move through the pores, but also bacteria from the environment.24) Biological dressings Biological dressings are dressings derived from natural sources (e.g. porcine small intestinal submucosa [PSIS], equine amnion dressings, bovine collagen sheets).9,47 These dressings provide an exogenous source of collagen, growth factors, hyaluronic acid, heparin sulphate, chrondroitin sulphate A and fibronectin.9,47 In addition, they can act as a scaffold for fibroplasia.9 Because the cost of biological dressings is high, a primary, nonadherent dressing, which can be changed more frequently, can be used to cover biological dressings.24 Advanced techniques In human medicine, new dressings, topical agents and techniques are being developed especially for the treatment of chronic wounds. New techniques include topical negative pressure (TNP) therapy, low-level laser therapy, hyperbaric oxygen therapy and ultrasound therapy. Good results with these techniques in human practice will possibly lead to their veterinary use in the future. Some have already been used in a few veterinary clinical cases. Topical negative pressure TNP therapy, also known as subatmospheric pressure therapy or vacuum-assisted therapy, uses subatmospheric pressure to promote or assist wound healing and is mainly used in chronic nonhealing wounds. TNP has multiple proposed mechanisms of action. The enforcement of negative pressure on the wound will lead to the removal of bacteria and excess fluid.84,85 This reduces the risk of infection and the distance for intercellular diffusion, thus improving wound oxygenation.84–86 TNP also results in mechanical forces to the surrounding tissues, which stimulate the local blood flow in the wound bed, the formation of granulation tissue and epithelialization.84,85,87,88 A vacuum is created by placing a foam or gauze dressing on the wound, which is connected by a tube to a vacuum pump. The gauze and tube are covered by an adhesive film sheet to provide an airtight seal. Negative pressure to the wound can then be applied constantly or intermittently. A negative pressure of $125 mmHg is recom - mended.89 Many papers have been published about TNP in the human literature, and the general conclusion is that there is a lack of high-level evidence to support the use of TNP in the treatment of wounds.84,85,87,88 However, some studies indicate that TNP therapy has advantages over the use of moist gauze dressings.87,88 Low-level laser therapy Low-level laser therapy (LLLT) is a cold laser used to stimulate wound healing by stimulation of fibroblast development, acceleration of angio - genesis, vasodilation and possibly by improving lymphatic drainage.90,91 This leads to an increase in granulation tissue formation, an increase in the formation of new capillaries and possibly a decrease in swelling.91 Meta-analyses have shown a highly significant effect of LLLT on wound healing in humans and horses.92–94 In addition to the stimulation of collagen formation, there are also improvements in the time needed for wound closure, the strength of the wound, the rate of healing, the number and rate of degranulation of mast cells, flap survival and analgesia.92,94 Therefore, LLLT stimulates wound healing in the inflammatory, proliferation and maturation phases.92,94 Hyperbaric oxygen therapy Since hypoxia is a common cause for nonhealing, chronic wounds, hyperbaric oxygen therapy (HBOT) has been used in the treatment of these wounds in humans.22 HBOT is considered to be an adjunctive therapy to standard wound management and should not replace proper wound management.95 Patients are placed in a compression chamber and allowed to breathe 100% oxygen with a pressure of 2.0–2.5 atmospheres absolute (ATA) for periods of between 1 and 2 hours, 1–2 times daily.96 The high oxygen concentration allows for complete saturation of haemoglobin molecules in the bloodstream and for more oxygen to be dissolved into the blood.95,96 To achieve local results at the wound site, the blood supply to the wound has to be at least partially intact.95 The higher oxygen tension in blood plasma results in upregulation of growth factors, downregulation of inflammatory cytokines, increased fibroblast activation, angiogenesis, antibacterial effects by stimulation of leucocytes and enhanced antimicrobial action.95,97 Wound management: a new protocol for dogs and cats 41 In addition to improving oxygen supply to the tissues, the delivery of nutrients will also be improved.95,97 Research into the effects of HBOT in human medicine is limited and application only seems to be justified when chronic wounds do not respond to other therapies. There are not many complications reported, but high oxygen concentrations are potentially toxic to the lungs and brain.96,97 Ultrasound Ultrasound is commonly used as a diagnostic tool, but it can also be used for therapeutic purposes such as wound healing. The main difference between diagnostic and therapeutic use of ultrasound is that the frequency for therapeutic purposes varies between 1 and 3.3 MHz, whereas the frequency for diagnostic purposes ranges between 5 and 10 MHz.11,93 Therapeutic ultrasound has thermal and nonthermal effects, but the main overall effects are reduction of the inflammatory phase and promotion of the initial proliferative phase.86,98–101 Ultrasound stimulates cellular recruitment, collagen synthesis, angiogenesis, wound contraction, fibro - blasts and macrophages, and fibrinolysis.86,98,101 The tensile strength of collagen is also increased after ultrasound treatment.86,101 A protocol for wound management in dogs and cats The different options for wound management have been described in the previous sections. Choosing which protocol to use depends on effectiveness, cost and patient benefit. A systematic approach, as described in Table 4, is recommended for efficient wound management. Step 1: Use a clean room and aseptic technique When treating a wound, further contamination and infection should be prevented. Therefore, patients with wounds must always be treated in a clean room and on a clean table. In addition, when manipulating wounds, (sterile) gloves should be worn as well as hair nets, face masks and clean coats. Instruments should be sterilized and the wound covered with sterile gauze or gel while clipping the surrounding hair and debriding necrotic tissue. Step 2: Obtain a complete medical history The medical condition of the patient can be important in selecting a treatment protocol. Some examples of conditions that influence wound healing include protein deficiency, anaemia, inadequate bloodsupply to the wound area, uraemia and vitamin A or C deficiency.18 Corti- costeroids or nonsteroidal anti-inflammatory drugs (NSAIDs) can delay wound healing.18 These factors must be considered and addressed when dealing with nonhealing chronic wounds. Step 3: Obtain information about the cause and age of the wound Information about the cause and time of wounding is important when assessing the level of contami - nation and the risk of infection. It also influences the protocol chosen. For example, traumatic wounds older than 4–6 hours should be considered to be infected and dealt with as such. Step 4: Make a complete assessment of the wound A thorough clinical assessment of the wound provides information about its characteristics and is necessary for further planning. The following should be assessed: • Type of wound. • Size and depth of the wound. • Tension of the surrounding skin. • Phase of wound healing. • Level of contamination. • Signs of inflammation. • Level of exudation. • Presence of necrotic tissue. Wound management: a new protocol for dogs and cats42 Table 4. A protocol for wound management in dogs and cats. • Use a clean room and aseptic technique. • Obtain a complete medical history of the patient. • Obtain information about the cause and age of the wound. • Make a complete assessment of the wound. • Debride necrotic tissue. • Remove contamination. • Choose the appropriate method of closure. • Choose the appropriate dressing. • Make regular assessments to monitor the progression of wound healing. Extra step for chronic or difficult to heal wounds: • When dealing with chronic wounds not responding to normal wound management, consider using an advanced technique. Wound management: a new protocol for dogs and cats 43 Step 5: Debride necrotic tissue Debriding necrotic tissue will accelerate the inflammatory phase of wound healing and the total healing time will be decreased. The most common techniques used are surgical and mechanical debridement. Preferably, all wounds with necrotic tissue are treated with surgical debridement first. Autolytic debridement should be considered in a patient in critical condition with a high anaesthetic risk, or when there is no clear demarcation line. Step 6: Remove contamination Removal of contamination will reduce the chance of infection and create better conditions for uncomplicated wound healing. Physiological solutions (e.g. sterilized saline or LRS) for pressured lavage are recommended in all patients. Dilution of contamination is more important than the antiseptic or antibacterial properties of the lavage fluid. Mild antiseptics, such as chlorhexidine, Dakin’s solution or povidone–iodine solution, can be considered for more heavily contaminated wounds, but their potentially toxic effects have to be taken into consideration. While irrigating, the spreading of bacteria under the wound edges or into the wound area must be prevented. Step 7: Choose the appropriate method of closure The different methods of wound closure have been described earlier in this chapter (Wound closure). Preferably, all noninfected wounds not containing necrotic tissue are closed by primary closure. In infected wounds or wounds containing necrotic tissue, delayed primary closure, secondary closure or healing by second intention must be considered. For example, in patients with a high anaesthetic risk, small wounds in areas without risk of wound contracture can be left to heal by second intention. Wounds that are too large to be closed by suturing, are not expected to heal completely by second intention or have a high risk of developing inappropriate wound contracture can be closed using tension-relieving techniques, skin grafts or flaps. Step 8: Choose the appropriate primary contact layer Topical medications and dressings have been discussed earlier in this chapter (Wound irrigation and topical medications; Wound dressings and bandages). There is a wide variety of products, but most wounds in their inflammatory phase can be treated with wet-to-dry bandages initially and glycerol medicated semi-occlusive dressings when granulation tissue starts to appear. Honey can be used, after initial wet-to-dry bandages, in heavily contaminated wounds not responding to the protocol described above. For selected patients, other products can be advised. Table 5 (overleaf) lists most of the available products and their indications. Step 9: Regularly reassess the wound It is important to monitor the progression of healing by regular assessment of the wound. The choice of dressings can be adjusted as the wound progresses through the four phases of healing. Step 10: Consider using an advanced technique When dealing with chronic or nonhealing wounds not responding to normal wound management, the use of an advanced technique should be considered. The techniques discussed earlier in this chapter (Advanced techniques) are not (yet) commonly used in veterinary practice, but they are available in some larger referral centres. Newer techniques, including TNP therapy, LLLT and HBOT, can be considered. Staged and multiple surgical debridements followed by advanced skin reconstruction will allow for closure of most wounds. Cost-effectiveness and patient and owner benefit The treatment of large and chronic wounds often requires special attention, care, time and commitment of both owner and the treating veterinarian. Multiple bandage changes lead to high costs. These costs can be minimized by using the right wound management protocol, the correct dressing and bandage change frequency and timely corrective surgical intervention. As expected, there will be differences in total costs in dogs and cats between treatments with traditional saline-impreg - nated gauze dressings and modern moisture-retentive dressings, as has been reported in human and equine patients.102–104 However, while cost and effectiveness are important factors, animal and owner comfort should also be considered. Patient factors to consider include the discomfort that accompanies dressing changes. For the owner, factors to consider include wound odour, leakage of exudate and the treatment duration associated with the number of visits to the veterinary clinic. Many of the benefits, both for the patient and the owner, can be achieved by applying modern dressings for moist wound healing. Conclusion/summary The options for wound management are so numerous that it is possible to choose an individual treatment for every wound and every phase of wound healing. If optimal wound management is desired, every wound should be assessed individ - ually and the treatment adapted regularly to the information that is gained from the wound evaluation. After following the 10-step protocol described above, a well-informed choice can be made between the available dressings. The modern moisture-retentive dressings have many benefits compared with the traditional saline-impregnated gauzes, but they can currently only be recommended in chronic wounds, where they stimulate wound healing more effectively, are more cost-effective and improve patient and client comfort. Wound management: a new protocol for dogs and cats44 Table 5. Topical medications and dressings. Wound colour Wound type Purpose of treatment Exudate Recommended dressing materials Black Necrotic wound Remove necrotic tissue ++ Saline gauze† Alginate Honey dressing* Silver dressing* + Alginate Saline gauze† Hydrogel Hydrocolloid Honey dressing Silver dressing $ In absence of signs of infection, the wound can heal under the scab Yellow Exudating wound Wound cleaning and ++ Alginate removal of debris Hydrofibre Foam Saline gauze† + Alginate Hydrofibre Foam Hydrogel* Hydrocolloid Saline gauze† Green Infected wound Wound cleaning and ++ Antimicrobial gauze dressing† clear infection Silver dressing† Honey dressing† + Antimicrobial gauze dressing† Silver dressing† Honey dressing† $ Antimicrobial gauze dressing† Silver dressing Honey dressing Red or pink Granulatingor Wound protection ++ Hydrofibre epithelializing and providing a Foam wound moist environment + Hydrogel* to stimulate healing Hydrocolloid* Hydrofibre Foam $ Hydrogel# ++ = wet; + = moist; $ = dry. †Cover with a secondary absorptive dressing. *Select one with good absorptive properties or use an absorptive secondary dressing to reduce the number of dressing changes. #For rehydration of the wound. 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(2004) Hyperbaric oxygen therapy for chronic wounds. Cochrane Database Syst Rev 2:CD004123. 97. Roeckl-Wiedmann I, Bennett M, Kranke P (2005) Systematic review of hyperbaric oxygen in the management of chronic wounds. Br J Surg 92:24–32. 98. Dyson M (2000) Ultrasound therapy. J Equine Vet Science 20:694–695. 99. Taskan I, Ozyazgan I, Tercan M et al. (1997) A comparative study of the effect of ultrasound and electrostimulation on wound healing in rats. Plast Reconstr Surg 100:966–972. 100. ter Haar G (1999) Therapeutic ultrasound. Eur J Ultrasound 9:3–9. 101. Young SR, Dyson M (1990) Effect of therapeutic ultrasound on the healing of full- thickness excised skin lesions. Ultrasonics 28:175–180. 102. Capillas Perez R, Cabre Aguilar V, Gil Colome AM et al. (2000) Comparison of the effectiveness and cost of treatment with humid environment as compared to traditional cure. Clinical trial on primary care patients with venous leg ulcers and pressure ulcers. Rev Enferm 23:17–24. 103. Harding K, Cutting K, Price P (2000) The cost-effectiveness of wound management protocols of care. Br J Nurs 9:S6, S8, S10 passim. 104. Xakellis GC, Chrischilles EA (1992) Hydrocolloid versus saline-gauze dressings in treating pressure ulcers: a cost- effectiveness analysis. Arch Phys Med Rehabil 73:463–469. Wound management: a new protocol for dogs andcats48 Chapter 3 General reconstructive techniques 49 Sjef C. Buiks, Marijn van Delden and Jolle Kirpensteijn • Triangular lesion • Square lesion • Bow tie technique • Walking sutures • Releasing incisions • Mesh releasing incisions • Advancement (U-) flap • Double advancement or H-flap • V-Y plasty • Z-plasty • Reading man procedure • Transposition flap • Interpolation flap • Rotation flap General reconstructive techniques50 Procedure The amount of skin at the edges of the defect is assessed. The defect is closed as a Y by beginning at each point and suturing towards the centre (18–23). Reference Fossum TW, Hedlund CS, Hulse DA et al. (2002) (eds) Small Animal Surgery, 2nd edn. Mosby, St. Louis, p. 162. Triangular lesion Overview An irregular-shaped cutaneous defect is converted into a simpler geometric pattern to facilitate wound closure. The closure begins at each corner of the defect and advances towards the centre. It can be used when sufficient skin is available on all sides of the defect. Otherwise, rotation flaps or unilateral or bilateral advancement flaps can be used. If too much tension is created when the defect is being closed, excised dog ears may be used as free skin grafts to cover the remaining defect. 22 The subcutis has now been closed. 23 Interrupted 4-0 nonabsorbable monofilament sutures are used to close the skin. 18 A formerly irregular lesion has been converted into a triangle. 19 The subcutaneous tissue is closed using 3-0 absorbable monofilament suture material. 20 Suturing progresses towards the centre of the lesion. 21 The final subcutaneous suture is put in place. 18 19 20 21 22 23 General reconstructive techniques 51 Square lesion Overview An irregular-shaped cutaneous defect is converted into a simpler geometric pattern to facilitate wound closure. The closure begins with suturing at each corner of the defect and then advancing towards the centre. A square lesion can be closed using the technique described below when sufficient skin is available on all sides of the defect. Otherwise, rotation flaps or unilateral or bilateral advancement flaps can be used. If too much tension is created when the defect is being closed, excised dog ears may be used as free skin grafts to cover the remaining defect. Procedure The amount of skin at the edges of the defect is assessed. The defect is closed starting at the corners of the defect and suturing towards the centre (24–27). Reference Fossum TW, Hedlund CS, Hulse DA et al. (2002) (eds) Small Animal Surgery, 2nd edn. Mosby, St. Louis, pp. 162–164. 24 The rectangular defect is slightly converted to a circular defect due to local tension lines. 25 Interrupted or continous sutures using 3-0 absorbable monofilament suture material can be used to close the subcutis. 26 The subcutaneous tissue is closed. 27 The skin is closed with interrupted sutures using 4-0 nonabsorbable monofilament suture material. 24 25 26 27 General reconstructive techniques52 Bow tie technique Overview The bow tie technique can be used to close circular defects where regular skin apposition would result in large dog ears. This technique depends on the availability of sufficient skin surrounding the defect. Two triangles are placed at opposite ends of the defect with their apex pointing towards the centre of the defect. The long axis of the defect is situated on the line of tension. The common axis of the triangles should be at 30 degrees to the long axis of the defect. The height of the triangles should equal the radius of the defect. The corners of the triangles are then transposed in such a way that the tension on the long axis is reduced and the defect can be closed effortlessly. Procedure The area around the circular defect is clipped and shaved in a wide quadrangular shape. The defect is cleaned if necessary (28). An incision is made following the predrawn lines and the skin of the two triangles bluntly undermined (29). The skin in between the circular defect and the triangles is then undermined (30). Stay sutures, using 2-0 nonabsorbable monofilament suture material, are placed to enable the skin to be transposed (31, 32). After transposing the two sides of the triangles, they are sutured into position using subcutaneous sutures of 3-0 monofilament absorbable suture material (33). The rest of the skin is apposed by placing a few subcutaneous sutures of 3-0 monofilament absorbable suture material (34). The skin is closed with interrupted sutures of 4-0 nonabsorbable monofilament suture material (35). References Alvarado A (1981) Reciprocal incisions for closure of circular skin defects. Plast Reconstr Surg 67:482–491. Fossum TW, Hedlund CS, Hulse DA et al. (2002) (eds) Small Animal Surgery, 2nd edn. Mosby, St. Louis, pp. 162–163. 28 Circular defect. Two triangles, both with their central axis at an angle of 30 degrees to the long axis of the tension lines, are drawn with a blue marker. The height of the triangles should equal the radius of the circular defect. 30 The skin adjacent to the circular defect is undermined using Mayo scissors. 29 The two triangles of skin are removed. 29 30 28 General reconstructive techniques 53 33 The corners of the triangles are sutured into position. 34 The skin edges are apposed using subcutaneous sutures of 3-0 absorbable monofilament suture material. 31 32 33 34 35 The end result of the bow tie reconstruction technique. 35 31, 32 The undermined sides of the triangles are dissected and moved towards their new position. General reconstructive techniques54 Walking sutures Overview Walking sutures are used to relieve mild to moderate tension. They gradually advance skin from the edge of a wound towards the centre (often from both sides). Walking sutures are placed through the underlying fascia at a distance closer to the centre of the wound than the bite through the subdermal fascia. 36 This lesion has too much tension to be closed primarily. 37, 38 The area is gently undermined using scissors. 39, 40 A suture is placed at a distance closer to the centre of the wound than the bite through the subdermal fascia. 36 39 37 38 40 41 Procedure Because the lesion has too much tension to be closed primarily (36) the area is gently undermined using scissors (37, 38). A suture is placed at a distance closer to the centre of the wound than the bite through the subdermal fascia (39, 40). A sliding knot is used to approximate the flap (41–44). A second suture is placed at the same level, but opposite side, of the flap (45) and the pro cedure is repeated, advancing the skin closer to the edge of the wound (46–48). Finally, full closure of the wound is facilitated (49, 50). General reconstructive techniques 55 41–44 A sliding k not is used to approximate the flap. 44 4342 45 A second suture is placed at the same level, but opposite side, of the flap. 45 46–48 This procedure is repeated, advancing the skin closer to the edge of the wound. 46 47 48 49, 50 The procedure is further repeated, facilitating full closure of the wound. 49 50 Releasing incisions Overview An elliptical wound can be closed with releasing incisions if there is sufficient adjacent skin. The closure begins by making one or two releasing incisions parallel to the length of the defect. The wound is closed first and then the releasing incision(s) are closed. The tension of the original wound is dispersed over the releasing incision(s). Alternatively, the releasing incisions can be allowed to heal by second intention. Procedure The amount of skin at the edges of the defect is assessed (51) and the positions for the releasing incisions marked (52). A releasing incision is marked parallel to the defect and an assessment General reconstructive techniques56 made as to whether the primary defect can be closed without tension. If not, a second releasing incision is made parallel to the first one, but opposite to the defect. Careful dissection of the bipedicle skin flap isperformed (53). The defect is closed by suturing the subcutaneous layer including the panniculus muscle. The use of 3-0 monofilament, absorbable suture is preferred (54). The skin is then closed in an interrupted suture pattern using 3-0 nonabsorbable suture material (55). After closure of the defect, both releasing incisions are closed, if possible (56). Reference Pavletic MM (2010) Atlas of Small Animal Wound Management and Reconstructive Surgery, 3rd edn. Wiley–Blackwell, Ames, pp. 266–267. General reconstructive techniques 57 51 An elongated incision can be closed with releasing incisions if there is abundant skin parallel to the incision. 52 The positions for the releasing incisions are marked. 53 The skin adjacent to the defect is undermined using Mayo scissors. 54 The primary defect is closed initially in the middle to assess if the skin edges are tension free. 55 The centre incision is opposed. 56 The end result after all the incisions have been closed. 51 52 53 54 55 56 Mesh releasing incisions Overview Mesh releasing incisions (or meshing incisions) are a variation on the releasing incision technique described above. The skin surrounding the defect is meshed in an attempt to decrease the skin tension and allow primary closure of the skin wound. The procedure is started by careful undermining of the skin and placing the incisions approximately 1 cm apart from each other in staggered rows. Procedure A wide quadrilateral area around the circular defect is clipped, shaved and prepared for surgery (57). The elasticity and the looseness of the skin in the proximity of the defect is assessed. The sites where the meshing incisions are to be made are marked (58) and subsequently incised using a No. 11 scalpel blade (59). The defect is sutured, leaving the meshed incisions open for second intention healing (60). Reference Pavletic MM (2010) Atlas of Small Animal Wound Management and Reconstructive Surgery, 3rd edn. Wiley–Blackwell, Ames, pp. 270 –271. General reconstructive techniques58 57 A wide area around the circular defect is prepared for surgery. 59 The marked spots are incised with a No. 11 scalpel blade. 60 The defect is sutured using 4-0 nonabsorbable monofilament suture material. 58 The meshing incision sites are marked with a sterile skin marker. 57 58 59 60 Advancement (U-) flap Overview One of the easiest and most versatile flaps used in veterinary surgery is the advancement (or U-) flap. A U-flap is a partially detached segment of skin and subcutaneous tissue. Its viability is based on maintaining blood circulation through its base and the subdermal plexus. The rationale behind this technique is that local skin in an area with a relative abundance or elasticity is used to close the primary wound. The secondary wound created can then be closed in a relatively tension-free fashion. Procedure This technique is used (in this case) to close an oval defect (61). The cutaneous trunci muscle at the edge of the incision should be noted. The locations of the two parallel vertical incisions of the U are marked (62). The two sides of the U-flap are then incised (63, 64). General reconstructive techniques 59 61 An oval defect is present. Note the panniculus muscle at the edge of the skin incision (arrow). 62 The positions for the two vertical incisions are marked. 63, 64 The upper and lower limbs of the U-flap have been incised. 61 62 63 64 The U-flap with the cutaneous trunci muscle attached is carefully dissected. The edges of the flap are manipulated using stay sutures (65). The General reconstructive techniques60 65 The U-flap with the panniculus muscle attached is carefully dissected. 66, 67 The panniculus muscle at the corners of the U-flap is sutured to the corners of the defect. 68 Interrupted sutures are placed. 65 66 67 68 cutaneous trunci muscle or subcutis at the corners of the U are sutured to the corners of the defect (66, 67). The skin tension is assessed by placing a couple General reconstructive techniques 61 69, 70 The layer containing the panniculus muscle is closed in a continuous suture pattern using 3-0 absorbable suture material. 71, 72 The skin is closed with interrupted sutures using 4-0 nonabsorbable monofilament suture material. 69 70 71 72 of interrupted sutures of 3-0 monofilament absorb - able suture material (68). A continuous suture pattern is used to close the subcutaneous layer containing the panniculus muscle (69, 70). The skin is closed with interrupted sutures of 4-0 non - absorbable monofilament suture material, starting at the corners of the defect (71, 72). General reconstructive techniques62 Double advancement or H-flap Overview An H-flap comprises two advancement (U-) flaps made in opposite directions. Procedure An oval defect is present is this case. The locations for the two parallel incisions of the H are marked (73). The two sides of the flap are then incised (74). The flap, with the cutaneous trunci muscle attached, is carefully dissected from the 73 One advancement flap has already been incised. Markings clearly point out the incision lines for extending the U into an H flap. 74 Both sides of the H-flap have been incised. wound bed. The edges are manipulated using stay sutures (75). The cutaneous trunci muscle at the edges of the H is sutured to the corners of the defect (76). The skin tension is assessed by placing a couple of interrupted stay sutures of 3-0 monofilament absorbable suture material. A continuous suture pattern is used to close the subcutaneous layer containing the cutaneous trunci muscle. The skin is then closed with skin staples or interrupted sutures of 4-0 nonabsorbable monofilament suture material (77, 78). 73 74 General reconstructive techniques 63 75 The H-flap with the cutaneous trunci muscle attached is carefully dissected from the wound bed. 76 The cutaneous trunci muscle at the edges of the U are sutured to the corners of the defect. 77 The skin is closed with skin staples or sutures. 78 A double advancement (H-) flap has been used in this dog to close a defect between the eyes. 75 76 77 78 General reconstructive techniques64 V-Y plasty Overview A V-Y plasty is a lengthening procedure used to relieve tension on a sutured wound. However, the tension-relieving effect is minimal and this tech - nique should be reserved for wounds with moderate tension in areas where there is no skin available for closure using other methods. 81 The primary defect is sutured. 82, 83 The V incision is closed by apposing the lateral edges, beginning at the tip. 84 The end result of a V-Y plasty reconstruction is shown. 81 82 83 84 Procedure An oval defect is present in this case. A V shape is drawn at least 3 cm from the wound edge (79). Both sides of the V-flap are then incised (80), the subcutis undermined and the primary defect is sutured (81). If necessary, the edges of the wound are carefully undermined. The incision is closed initially by apposing the outer edges, beginning at the tip of the V (82, 83). Closure of the wound is completed by creating a Y-shaped configuration to the incision (84). 79 A V shape is drawn at least 3 cm from the edge of the wound. 80 The V is incised. 79 80 General reconstructive techniques 65 Z-plasty Overview A Z-plasty is used to increase the length of a skin area (e.g. restrictive scar tissue). A Z-plasty involves the simultaneous transposition of two equilateral triangular local flaps. The theoretical amount of skin lengthening varies with the length of the limbs of the Z-shaped incision and with the angle between the limbs. Procedure An incision line is marked on the skin parallel to the direction in which the defect will be closed. This is the central limb of the Z (85) and it should be parallel with the line of tension (i.e. perpendicular to the wound requiring tension relief). The two side limbs of the Z are drawn on the skin at an angle of 45–60° to the central limb. To guarantee survival of the skin betweenthe Z and the wound, the incision should not be made too close to the wound edge (86). The triangles formed by the Z are coloured to make the flap clearer (87). The limbs of the Z are then incised. The corners of the Z are incised with relatively sharp angles; however, blunting the angle a little will preserve the blood supply to the tip (88). 85 The central limb of the Z is drawn perpendicular to the wound requiring tension relief. 86 The Z limbs are drawn at an angle of 60 degrees to the central limb. 87 The triangles formed by the Z are coloured in order to make the plasty clearer. 88 The three limbs of the Z are incised. 85 86 87 88 General reconstructive techniques66 Tension will open up the Z (89). Each triangular flap is then carefully undermined (90). The position of the Z before the two triangular flaps are moved to their new position (91) and the final result of the Z-plasty after the two flaps have been moved (92) are shown. The corners of the Z are sutured using 91 The original position of the the triangular parts of Z- plasty is shown. 92 The final position of the triangular parts of the Z-plasty is shown. 89 Tension opens up the Z. 90 Each trianglular flap and the skin between the defect and the Z is undermined using Mayo scissors. 89 90 91 92 General reconstructive techniques 67 3-0 absorbable monofilament suture material (93). The Z-plasty and the defect are sutured using 4-0 93 The corners of the Z-plasty are sutured. 94, 95 The Z-plasty and the defect are sutured. 93 94 95 nonabsorbable monofilament suture material (94, 95). 96 Illustration showing the reading man surgical procedure. (A) Circular defect. (B) Determining the direction of the central limb of the Z-plasty (dotted lines). To obtain a fine scar, this line should be perpendicular to the relaxed skin tension lines (RSTL). (C) The central limb of the Z-plasty is drawn as an imaginary tangential line passing through the margin of the circular defect. (D, E) Other limbs of Z-plasty are planned with angles of 45º and 60º according to an unequal Z-plasty concept. (E) The flap nearest the defect (f1) is used for the defect closure, and the other flap (f2) is transposed for closure of the donor site of the first flap with a Z-plasty manoeuver. (F) The final view after defect closure. (Adapted from Mutaf M, Sunay M, Bulot Ö (2008) The “Reading Man” procedure: a new technique for the closure of circular skin defects. Ann Plast Surg 60:420–425.) General reconstructive techniques68 Reading man procedure Overview The reading man procedure can be used in a variety of ways. It is an effective method of closing a round defect. Two skin flaps are designed in an unequal Z- plasty manner. These two flaps provide a maximum amount of tissue relaxation, which results in decreased tension (96). Procedure The skin tension lines in the area of the defect are determined. Two parallel lines are drawn perpendicular to the direction of the skin tension lines (97). The axis of the Z is placed parallel to the line of skin tension. The incision should be one-and- a-half times the diameter of the defect. Lines are then drawn at an angle of 60º at the end of the Z and at an angle of 45º at the beginning of the Z (98). Both flaps are incised and then undermined using scissors (99). Stay sutures are placed to move the flaps. The first flap (1) is used to cover the area of the primary defect and the second flap (2) to cover the donor area (100, 101). The flaps are sutured with a continuous subcutaneous pattern and simple interrupted skin sutures (102, 103). References Mutaf M, Sunay M, Bulut Ö (2008) The “Reading Man” procedure: a new technique for the closure of circular skin defects. Ann Plast Surg 60:420–425. 96 A B a RSTL a + ! a C D E F 60º f1 f2 45º 60º f1 f2 General reconstructive techniques 69 100, 101 Stay sutures are placed. Flap 1 is used to cover the area of the primary defect, flap 2 to cover the donor site. 102, 103 The flap edges are sutured to the defect and the subcutis and skin closed. 100 101 102 103 97 Two parallel lines are drawn in the direction of the skin tension lines. 98 The outline of the Z is shown. 99 The flaps are incised along the predrawn lines and they are then undermined. 97 98 99 f1 f1 f2 f2 General reconstructive techniques70 Transposition flap Overview A transposition flap is a local pedicle flap that transposes skin from an area adjacent to the skin wound to the defect that is to be closed. The length of the flap is predetermined and different angles can be used. The most common angle to the wound is 90º. Procedure The base of the flap should equal the width of the defect (104, 105) and the length of the flap should equal the length from the outer pivot point to the most distant edge of the defect (106, 107). The donor flap is marked using a sterile marking pen (108). The flap edges are incised and the flaps lifted (109, 110). The flap is then transposed into the defect (111). Finally, the flap is sutured into place in two layers (112, 113). References Fossum TW, Hedlund CS, Hulse DA et al. (2002) (eds) Small Animal Surgery, 2nd edn. Mosby, St. Louis, p. 166. Hedlund CS (2006) Large trunk wounds. Vet Clin North Am Small Anim Pract 36:847–872. Pavletic MM (2010) Atlas of Small Animal Wound Management and Reconstructive Surgery, 3rd edn. Wiley–Blackwell, Ames, pp. 322–325. 105 The base of the flap, which should equal the width of the defect, is marked. 106 The length of the flap is measured. It should equal the length from the outer pivot point to the most distant edge of the defect. 107 The length of the flap is marked. 104 The width of the defect is measured. 104 105 106 107 General reconstructive techniques 71 111 The flap is transposed into the defect. 112 The flap is sutured to the edges of the wound defect. 113 The end result of a transposition flap reconstruction is shown. 109 The edges of the flap are incised and the flap is lifted. 110 The flap is lifted from its wound bed. 109 110 111 112 113 108 The complete flap is marked. 108 General reconstructive techniques72 Interpolation flap Overview An interpolation flap is a transposition pedicle flap, traversing an area of normal skin between the donor site and the recipient site. This flap is similar to the transposition flap apart from the fact that it lacks a common border with the wound. The size of the flap must take into account the width of the defect and the loss of length that will occur when the flap is rotated into the defect (114). Because there is a skin bridge between the flap and the defect, the subcutaneous tissue on the underside of the flap is exposed to this bridge and could become infected. This excess skin is excised after 14 days. An interpolation flap can be used when there is insufficient skin adjacent to the defect, but abundant skin is available in close proximity of the wound. Alternatively, a single-stage interpolation flap can be performed with a bridging incision made between the donor and the recipient sites. Procedure Stage 1. The area around the circular defect is clipped and shaved in a wide quadrilateral area. If necessary, the defect is debrided. The elasticity and looseness of the skin in the proximity of the defect is assessed. The donor flap is marked using a sterile marking pen. The base of the flap should equal the width of the defect and the length of the flap should 115 The circular defect has been excised. The donor flap is outlined in blue. 115 114 Schematic representation of the interpolation flap. The base of the flap equals the width of the defect (line 1) and the length of the flap equals the distance from the outer pivot point to the most distant edge of the flap (line 2) 114 1 1 2 2 equal the length from the outer pivot point to the most distant edge of the defect (115). Incisions are made along the predrawn lines and the donor flap is undermined, using Metzenbaum scissors, beginning at the top of the rectangle. Staysutures, using 2-0 monofilament (non)absorbable suture material, are placed in the corners of the flap in order to move it into the recipient site (116). The flap is sutured into position by placing a few subcutaneous stitches (117). The donor bed is then closed (118). The subcutis and skin are sutured using 3-0 absorbable monofilament suture materials (119). General reconstructive techniques 73 119 After suturing the skin, part of the subcutaneous side of the flap is still accessible (identified by the forceps). 119 116 The donor flap (which is covering the defect) is ready to be transposed. 117 The subcutaneous tissue of the donor flap is sutured to the recipient site with interrupted sutures. 118 Note that the segment of the flap overlying the intervening skin is neither attached to the underlying skin nor to the defect. 116 117 118 Stage 2. The bridging skin is excised 14 days later (120). The skin is incised following the blue dotted line and sutured to the donor and recipient sites (121–123). (Note: Because the overlying skin surplus produced in stage 1 of the procedure is liable to infection, an interpolation flap is in - frequently used as described and illustrated above. More commonly, a bridging incision is made or the flap ends are sutured together (forming a tube) so that the skin does not touch the underside of the flap [see Chapter 9, Genicular axial pattern flap].) References Fossum TW, Hedlund CS, Hulse DA et al. (2002) (eds) Small Animal Surgery, 2nd edn. Mosby, St. Louis, p. 166. Hedlund CS (2006) Large trunk wounds. Vet Clin North Am Small Anim Pract 36:847–872. Pavletic MM (2010) Atlas of Small Animal Wound Management and Reconstructive Surgery, 3rd edn. Wiley–Blackwell, Ames, pp. 328–331. General reconstructive techniques74 121 The superfluous skin is incised and removed. 122 The original lesion and the recipient lesion are now clearly visible after removal of the bridging skin. 123 The completed interpolation flap reconstruction is shown. 121 122 123 120 The part of the donor flap that will be removed is outlined. 120 Rotation flap Overview A rotation flap is used to cover small, triangular defects. The flap can be used in any location and is independent of the size of the triangle. The flap has a semicircular form and is rotated around a pivot point. The length of the arc-shaped incision should be approximately four times the length of the baseline of the defect. Rotation flaps can be single or paired. Paired flaps can be used to close wider defects. Procedure The area around the triangular defect is clipped and shaved (124). A curved incision line is drawn using a sterile marking pen. The total length of the semicircular line should be four times the baseline of the wound. The pivot point is the lower right corner of the triangle (125). A curved incision is made and a small piece of the flap is undermined beginning at the top of the triangle. Stay sutures are placed in the corner of the flap to facilitate manipulation of the flap (126). The skin is under - mined in a stepwise fashion until the flap can be rotated into the defect with minimal tension (127). General reconstructive techniques 75 124 A triangular defect is present on the trunk. 125 The arc-shaped incision line is four times the length of the baseline of the wound. 126 An arc-shaped incision is made. Two stay sutures are placed in the corner at the top of the triangle to manipulate the flap into position. 127 Half of the skin flap is undermined. In this case this was sufficient to cover the whole defect without too much tension. 124 125 126 127 The flap is sutured into position by placing a few subcutaneous sutures (128). The subcutis is sutured with a continuous monofilament suture pattern and the skin with an interrupted monofilament suture pattern (129). References Fossum TW, Hedlund CS, Hulse DA et al. (2002) (eds) Small Animal Surgery, 2nd edn. Mosby, St. Louis, pp. 162 and 166. Hedlund CS (2006) Large trunk wounds. Vet Clin North Am Small Anim Pract 36:847–872 Pavletic MM (2010) Atlas of Small Animal Wound Management and Reconstructive Surgery, 3rd edn. Wiley–Blackwell, Ames, pp. 332–333. General reconstructive techniques76 128 The rotation flap is sutured into the recipient bed. 128 129 129 The skin edges are apposed and the skin sutured. • Introduction • Background information on avascular and microvascular skin surgery • Avascular mesh graft • Microvascular flap transfer • Conclusion/summary • References Chapter 4 Avascular and microvascular reconstructive techniques 77 Guido Camps and Jolle Kirpensteijn Introduction This chapter aims to give a review of the current techniques being used in the field of avascular and microvascular flap transfer procedures in veterinary medicine. Microvascular flap transfer is specialized surgery that yields many benefits when compared with fixed flap or avascular graft operations. Avascular mesh graft transfer techniques for closing wounds will be described. The background to flap transfer and its relation to and development into microvascular free flap transfer is discussed, followed by a general description of the technique. A detailed overview of the results of published scientific articles is provided, with emphasis on the location of recipient vessels for microvascular free flap transfers. Background information on avascular and microvascular skin surgery The act of closing a wound and restoring the skin has the goal of creating the best conditions to allow recovery in the shortest amount of time with the best cosmetic results. This implies that the exposed lesion needs to be covered completely by functional, healthy skin. In some wounds the nature of the lesion or of the surgical procedure makes it impossible to achieve wound closure with conventional suturing techniques. The lesion may simply be too large because so much skin had to be excised due to the original wounding or too much skin was lost during the creation of the wound. When faced with these situations, other solutions must be explored in order to close the wound satisfactorily. There are two primary options for closing such wounds: (1) using pedicle flaps, which remain attached to the skin, or (2) using free grafts, sometimes referred to as free flaps.1 The use of free flaps has become more common with the advent of microvascular surgery, which allows the surgeon to reconnect the free flap directly to the body’s circulation, thus ensuring its survivability. A pedicle flap remains attached to the rest of the skin via its pedicle and is moved towards the wound to cover it. This has the advantage that it remains connected to the body’s circulation. A pedicle flap can be used to cover large wounds.2 The main disadvantage, however, is that the surgical techniques available to the surgeon are limited by the size of the flap. Problems can arise from overstretching the flap to cover the wound, thereby cutting off the blood vessels necessary for sustaining the flap. Additionally, the procedure must sometimes involve stretching the flap in a direction other than how nature intended. This stretching not only puts pressure on the vessels, it also seems to be a painful process, specifically in those areas where skin is sparse and tight due to movement. In contrast, a free graft (flap) is taken away from its original site and placed over the wound. Therefore, it is completely cut off from the body’s original circulation. Indications for the use of free flap transfers include a wound beyond the reach of pedicle flaps or when it is necessary to cover taut, sparse skin areas that do not have enough surrounding skin to stretch to cover the wound. This is usually the case with large distal wounds on the limbs.3 Healthy granulation tissue or a fresh wound are required for a successful free flap transfer procedure. The process of grafting is in itself not without risks. The biggest complication in grafting is infection, which may lead to necrosis ofthe graft and the recipient site, which in turn leads to scarring and delayed healing.4 Most problems are the result of delayed vascularization of the graft (e.g. due to fluid build-up between the graft and recipient site). In free graft transplants, three stages of acceptance (or take) of a graft are recognized: prior to revascularization, the stage of vascular - ization, and the stage of final take. In the first stage only fibrin binds the graft to the site; after 12 hours, vascularization begins and this is completed after 12 days. Final healing, including contraction, pig - mentation and innervation, may take up to 18 months. Complications with conventional free grafts arise when the graft necrotizes due to insufficient circulation between the graft and the body’s blood supply. There are three main causes for problems with vascularization:3 • Physical movement of the graft can severely undermine the body’s attempt at revascularization. As mentioned above, during the first stage the graft is only stuck to the recipient site by a fibrin seal. If the graft moves, it can dislodge this seal and prevent the development of newly formed vessels or the connection of vessels to the graft. Free grafts are often kept as thin as possible to allow fast revascularization and guarantee the availability of essential products to survive through diffusion in the early stages of healing. • The second complication is the occurrence of fluid build-up (e.g. a haematoma) underneath the graft. Since the recipient site is a wound, it often keeps bleeding after application of the graft and a haematoma or seroma can form underneath the graft and prevent revascularization, which in turn leads to necrosis of the flap. • Lastly, due to the initial decreased circulation underneath the flap, this area will be infiltrated to a lesser extent by the body’s immune cells. Because of this, the area can become infected, which will not only prevent vascularization, but also compromise the wound bed and the flap directly, leading to flap death. Avascular and microvascular reconstructive techniques78 Avascular mesh graft Overview A mesh graft is a nonvascularized piece of skin from a distant and different part of the body that is transferred to the recipient defect side. Because of the nonvascularized nature of the graft, extreme care must be taken in expediting atraumatic harvesting and attachment of a flap. This is best facilitated by using two surgical teams. Types of mesh grafts There are two major types of mesh grafts: full- thickness and partial-thickness. Partial-thickness mesh grafts are often obtained using electrically operated mechanical dermatomes, which are expensive. Grafts can also be obtained manually. Full-thickness grafts are made using the scalpel blade as described below. Full-thickness grafts have the advantage of better cosmetic end results (especially hair growth). Partial-thickness grafts have a better chance of survival and the donor site does not need to be sutured after the harvesting. Wound bed preparation The wound bed must be prepared in such a way that it will be able to receive the mesh graft (130, 131). This includes: • Removing wound fluid, crusts, dead tissue and possible foreign bodies, thus creating a healthy granulation tissue bed. This should be performed in advance of the grafting procedure. • Inspecting the epithelial borders and, if necessary, cleaning up the wound edges and removing epithelialized tissues. • Coagulation of any cut blood vessels that are present. • Removing the top layer of the granulation tissue (if necessary). • The recipient side should be covered with a saline- or blood-soaked sponge to prevent dessication while the donor side is being prepared. Avascular and microvascular reconstructive techniques 79 130, 131 (130) This cat has a severely necrotic skin wound on its distal limb. (131) The wound is managed appropriately until a healthy granulation tissue bed has formed. 130 131 Donor side preparation The donor site should be carefully selected, so the defect can be closed without tension (132). Attention should also be directed to the growth pattern and hair colour to achieve the most acceptable cosmetic results. An impression is made of the recipient bed in order to estimate the size of the donor bed. The graft will expand significantly in correlation with the number of slits (or meshes) that are made in the graft, so either a comparable size wound is made or one slightly smaller. Technique The graft must be kept moistened during the complete procedure. The site is prepared aseptically and a marker used to determine the margins of the graft (133). The skin is then incised along the marked lines (134). The skin only is elevated from the wound bed and the panniculus muscle is not incorporated into the graft. To facilitate removal, the edges of the graft can be sutured to a roll of sterilized bandage material (135). The roll is used to put tension on the graft and lift it up from the donor bed. As much subcutis as possible is removed from the graft so that the hair follicles are visible. The graft is rolled slowly over the bandage material and attached to the material with a few sutures. The graft is then detached and freed from the remnants of subcutaneous fat. A No. 11 blade is used to make the meshes (slits) in the graft. The distance between the slits should be less than 1 cm and they are staggered in alternate rows (136, 137). The graft is placed as soon as possible on the prepared recipient side. The edges of the graft are sutured or stapled to the recipient side (138, 139). Sutures within the graft are usually not necessary, but in large mesh grafts a few sutures can be placed inside the graft edges; these prevent dead space, improve contact Avascular and microvascular reconstructive techniques80 132 Skin tension is checked at the donor site. 133 A paper template is made of the recipient site to determine the dimensions of the graft. 134 The harvest site is grafted by incising along the marked lines. 135 The subcutaneous tissue is removed from the deep aspect of the graft by careful dissection. 132 134 133 135 Avascular and microvascular reconstructive techniques 81 138, 139 The graft is sutured to the recipient site. 136, 137 The graft is meshed with incisions (slits) that are <1 cm apart and staggered in alternate rows. 140, 141 The donor site is closed primarily. between graft and bed and decrease seroma formation. The donor bed is then closed (140, 141). The use of a nonmeshed graft is discouraged. The mesh prevents fluid build-up under the graft. A seroma will significantly decrease the survival (acceptance) of the graft. 136 138 140 141 139 137 Aftercare Aftercare is an important aspect of the procedure. A well-padded, nonadhesive bandage that is able to absorb excess wound fluid should be applied and not removed for 3–5 days (142). It must be kept as clean and dry as possible. In this period, plasmatic imbibition will take place, which will nurture the graft, and vessels will be able to reconnect. After this initial period, very careful bandage changes will be necessary. The graft will adhere in 7–14 days and epithelialization of the slits will take place within a month (143). Cage rest is essential during the first 10 days. Casts and splints are only used when other means of immobilization (e.g. a Robert Jones bandage) are not possible. Mesh grafts have a 50–90% chance of survival (144). Microvascular flap transfer Overview In order for the success of a free graft to be less dependent on the body’s ability to revascularize the flap, microvascular surgical techniques can be used that directly connect the flap to the circulatory system. This combines the circulatory advantage of pedicle flaps with the possibility of treating wounds in any location. For this procedure, the free flap is designed by taking a skin flap with an afferent and efferent vascular pattern. Specifically, the vessels that supply and drain theflap are identified, the flap is freed and placed in the recipient area, and the vessels are anastomosed to the vessels at the recipient site. This creates a blood supply to the graft, independent of the body’s ability to revascularize the flap through the wound bed.5 General concepts of microvascular flap transfers Materials An operating microscope with good optics, 9-0 to 11- 0 suturing material, vascular clamps, microscissors, jeweller’s forceps, ophthalmic needle holders, vessel dilators and coupling devices are required for performing microvascular skin flap transfers. In order to ensure that there are functioning recipient vessels at the transfer site, an angiography of the recipient area should be performed. Obtaining the flap To obtain the flap that will be used in the procedure, a graft must be harvested from an appropriate area. The graft must be large enough, not be in the area undergoing surgery and have a circulatory system that allows for microvascular surgery afterwards. Sites commonly used are the medial side of the thigh and the upper shoulder area. The lower craniolateral thoracic area can be used as a harvest place for two specific reasons: Avascular and microvascular reconstructive techniques82 142–144 A bandage is applied to protect the meshed wound (142). Follow-up photographs are shown at 1 month (143) and 6 months (144) postoperatively, respectively. 142 144 143 it has good hair growth, leading to a more aesthetically pleasing result, and the skin is relatively thin, resulting in quick vascularization.3 Other sites and their respective sizes will be covered in more detail later. Preparing the vessels The vessels within the flap are identified and prepared using magnification. They should be clamped and transected in preparation for reattachment. After the wound site (recipient site) has been cleaned and prepared for the flap, recipient vessels are selected. Both vessel ends are prepared for microvascular anastomosis by irrigation with heparinized saline. To create actual circulation within the flap, the artery of the flap is first anastomosed to an artery of the recipient site. After this the vein is connected to a vein in the recipient site with small size nonabsorbable suture material.6 Complications The main risk with this procedure is necrosis of the flap because of faulty circulation. Excluding the possibility that the anastomosis between the vessels was badly performed, faulty drainage can be caused by thrombosis within the flap blocking the circulation, or it can be due to too much pressure on the draining vein. A change of flap colour would be indicative of complications. Anticlotting medication (e.g. aspirin) can be given to help prevent a thrombus from forming (Table 6). Checking the arterial blood flow into the flap can be achieved with Doppler ultrasound.7 Poor or occluded drainage of the veins can occur due to pressure on or kinking of the efferent veins. An accurate estimation of the appropriate length of the vein to be used in the flap is essential for flap survival. It is important to ensure that the patient cannot damage the newly connected vessels through postoperative biting or licking of the wound. It is also important that the site where the flap was harvested is checked carefully. Circulation A study in 1973 challenged the contemporary idea that blood vessels in the skin were more important for thermoregulation than for nutrient delivery.8 The authors compared human and animal blood supply to the skin and differentiated between three types of vessels: segmental, perforator and cutaneous vessels. Based on the blood supply, skin flaps can be classified as cutaneous, arterial or island flaps. The authors found that island flaps could survive if only their main pedicle vessels remained intact, as the severance of all other vessels did not have an adverse effect on flap survival. Taking this fact into consideration, they performed successful island flap transfers in pigs by Avascular and microvascular reconstructive techniques 83 anastomosing the vessels of the island flap via microvascular surgery. The first mention of microvascular surgery in veterinary medicine was in 1986 when cervical flaps in the dog were successfully performed.9 Certain flaps were found to be successful based on the superficial cervical vessels supplying blood to the cervical region. The supplying vessels were all observed to originate from between the omotransversarius and trapezius muscles, lying in a craniodorsal direction towards the cutis. Eight transfers were performed using the cervical flap and six of the eight grafts survived. The two graft failures were caused by decreased circulation, in one case because of arterial insufficiency and in the other because of poor venous drainage. Following these experimental flap transfers, in 1991 the use of a cervical flap was reported in seven clinical cases, with a success rate of 100%.12 Table 6. Available antithrombotic medication. Anti-thrombotic medicine Dosage Heparin flush6 Heparin saline flush of vessel ends before anastomosis Acetylsalicylic acid (ASA)10 0.5 mg/kg (q12h) for 3–14 days postoperatively Acetylsalicylic acid (ASA) 2 mg/kg q12h for 4 days from day before surgery Dextran 407 Intraoperative administration, dosage n/a Preventing complications A review of free skin flap transfer by microvascular anastomosis established five criteria for a successful skin flap transfer: adequate size, minimal donor site morbidity, a consistent vascular pedicle, a vascular diameter of at least 0.5 mm and a minimal vascular pedicle length of 4.0 cm.10 In cervical flap transfers, an incision is made in the skin from the top of the scapula to the cranial point of the shoulder. The flap, which is located cranial to this incision on the cervical area, gets its blood from the pedicle, which can be found via the earlier mentioned incision. The flap is dependent on the pedicle for its blood supply for 8–14 days postoperatively. The critical ischaemia time for the flap is 13 hours (survival >50% if reperfused). It is important to counteract the postoperative occlusion as soon as possible, at least within 4 hours. Acetylsalicylic acid (ASA) (0.5 mg/kg PO for 3–14 days post surgery) can be given to prevent clotting in the flap. Flap transfers are an all-or-nothing procedure; either the whole flap dies or, hopefully in the majority of cases, the whole flap survives. Donor sites and results The first large-scale overview of microvascular free flap transfer results was presented in 1998.7 Case records from all animals undergoing microvascular reconstructive procedures at the Western College of Veterinary Medicine and Michigan State University were reviewed in the period from 1985 to 1996. The main variable that was recorded was flap survival rate. The authors also tried to find reasons why in specific instances the flap did not take. The risk factors evaluated were ischaemia time, institution, surgical experience, experience of the assistant surgeon, antithrombotic therapy, anastomosis techniques and flap type. The flap survival rate reported in this case series was 93%. No significant relationships between flap survival and any of the aforementioned risk factors were observed, with the exception of the experience of the primary surgeon. The dogs needing reconstructive surgery used in the study were a group of mixed gender, breed and size. The most common indications for surgery included cancer and car accidents. The vessels of the flap were anastomosed to the recipient site using both end-to- end and end-to-side ligation techniques. End-to-side repairs were favoured when a notable discrepancy in size between the flap and recipient vessel size was apparent. The authors noted that the main intraoperative complication in surviving flaps was due to poor preparation of the vessel ends before anastomosis. It is important that the vessel ends are cleared of adventitial tissue in order to prevent adventitial tissueprolapsing into the lumen of the anastomosed vessel. Muscle flaps An additional result from the above study is the shift it caused from the use of purely cutaneous flaps to musculocutaneous flaps or muscle flaps covered with a (mesh) skin graft. The authors recommended that muscle is superior to skin in promoting revascularization of ischaemic wound beds, thus reducing infection rates and providing a more rapid initiation of bone healing. Using muscle tissue in the same manner as a cutaneous pedicle flap has been described in the literature.12 The semitendinosus muscle was used to create a flap to cover a lesion caused by a tibial fracture. The authors used a muscle flap because of its healing properties, especially in support of healing the underlying bone, but they also reported a partial skin necrosis. Muscle flaps would be of great interest for use as free flaps for transfer surgeries. The use of free muscle flaps has been further described in another study.13 The rectus abdominis muscle was used and a cutaneous mesh graft added. The donor site morbidity and survival of the rectus abdominis muscle was assessed following transfer to a medial femorotibial defect in dogs. First, the dimensions of the abdominis flap were examined using angiography on flaps harvested from canine cadavers. In the seven dogs used for the experiment, the mean length and width of the excised rectus abdominis muscles were 225 (SD 48) mm and 55 (SD 6) mm. The muscular transfer was performed through anastomosis of the caudal epigastric artery and vein to the saphenous artery and medial saphenous vein, after which the muscle was covered with a mesh skin graft. The procedure was observed to have caused minimal donor site morbidity. Survival rate of the muscle flap after microvascular transfer was 100% and angiography confirmed vascular patency. With the exception of one partial necrosis, all the skin grafts survived. On the basis of this, the authors concluded that the rectus abdominis muscle can be successfully transferred to a medial femorotibial defect and can successfully serve as a bed for acute skin grafting. The authors made special mention of the excellent aesthetic result of this procedure and attributed this to the fact that the mesh skin graft can be rotated so that the grain of the hair is in line with the coat surrounding the graft. The rectus abdominis flap is very versatile and can also be used for other locations (145–148). Avascular and microvascular reconstructive techniques84 Avascular and microvascular reconstructive techniques 85 145–148 (145) A dog with a large defect in the hard palate following resection of a melanoma. (146) Following failure of a local buccal flap, a rectus abdominis muscle was transferred into the mouth. (147) The anastomosis post surgery. (148) The surgery resulted in an excellent outcome. Anaesthesiology Circulation is an important issue when it comes to flap transfers. A human study, which demon - strated that lidocaine epidural anaesthesia increased microcirculatory blood flow in flap transfer patients, encouraged veterinary applications. 145 147 148 146 One study assessed the effects of epidural anaesthesia using lidocaine on microcirculatory blood flow, volume and velocity in free fasciocutaneous flaps in dogs.14 Ten adult dogs, weighing 20–25 kg, had an orthotopic transfer performed with a medial saphenous fascio - cutaneous free flap (Table 7) by anastomosing the primary flap vessels back to the medial saphenous vessels. Blood flow, volume and velocity values in the flaps were checked throughout the procedure and compared with the values recorded after epidural anaesthesia. The values did not change significantly over time. The only change that did occur was a reduction in the mean arterial pressure, which remained below reference values throughout the whole procedure. The differences between these results in dogs and humans are attributed to differences in circulatory build-up between humans and dogs and cats, as has already been reported.8 The implication of these results is that epidural anaesthesia with 2% lidocaine is of no direct use in dogs undergoing microvascular free flap transfer. Recipient vessels Two publications gave an overview of access to the recipient vessels for free flap transfer in the head and Avascular and microvascular reconstructive techniques86 neck area and on the fore- and hindlimb, common sites for difficult-to-close wounds.15,16 These studies were performed with the aim of developing and evaluating surgical approaches to arteries and veins that might be used as potential vessels to receive free tissue transfers. The method for both studies was similar: the circulatory system of a freshly euthanized dog was flushed and the cadaver was fixed. After this, the circulatory system was filled with a mixture of silicone and barium, and radiographs of the cadaver were made in order to locate the major arteries and veins in both the head and neck and the limb areas. On the basis of a second cadaver, prepared in the same manner, surgical approaches were developed. These approaches were further fine-tuned on the basis of feedback from other surgeons who performed these approaches on fresh cadavers. Cervical and cranial recipient vessels Seven surgical approaches to recipient vessels in the cervical and cranial area have been suggested.15,16 Infraorbital access Artery: infraorbital artery (1–1.5 mm diameter); vein: superior labial vein (3 mm diameter), or facial vein (4–5 mm diameter). Table 7. Microvascular flaps mentioned in veterinary literature. Location Species Rate of Location of vessels success Superficial cervical cutaneous9 Dog 75% The angle formed by the omotransversarius and trapezius Superficial cervical cutaneous7 Dog 90% The angle formed by the omotransversarius and trapezius Medial saphenous fasciocutaneous7 Dog 100% N/A (149–154) Caudal superficial epigastric7 Dog 100% N/A Trapezius7 Dog 100% N/A Latissimus dorsi7 Dog 50% N/A Caudal sartorius7 Dog 100% N/A Trapezius musculocutaneous7 Dog 100% N/A Saphenous musculocutaneous7 Dog 100% N/A Cranial abdominal myoperitoneal7 Dog 100% N/A Footpad7 Dog 100% N/A Rectus abdominis13 Dog 100% Pudendoepigastric arterial and venous trunks from the deep femoral artery and vein (in two out of seven dogs the vessels sprang directly from deep femoral artery and vein) Lateral thoracic17 Cat 100% Cranially directed external thoracic artery; 1st branch of the axillary artery Avascular and microvascular reconstructive techniques 87 149–154 (149, 150) A large wound is created following excision of a grade 2 mast cell tumour. (151, 152) The recipient vessels are prepared and a medial saphenous flap anastomosed to repair the defect. (153) This photograph was taken just before radiation therapy was commenced. (154) This is the area 1 year later. The dog remained tumour free at the surgical site. 149 150 151 152 153 154 A horizontal incision is made over the infraorbital foramen, along the long axis of the infraorbital artery. The levator labii maxillaris muscle is incised cranial to the superficial bifurcation of the superior labial vein and facial vein and retracted to expose the infraorbital artery. Retracting the skin ventrally exposes the superior labial vein. Alternatively, the facial vein dorsal to the superior labial vein can be used. The artery is more easily isolated because it is devoid of branches, in contrast to the vein, which contains many side branches. Temporal access Artery: superficial temporal artery (1.5 mm diameter); vein: superficial temporal vein (3 mm diameter) or rostral auricular vein (2–2.5 mm diameter). The platysma muscle is incised via a vertical incision along the ear canal and the superficial temporal vein and rostral auricular vein are exposed next to the parotid salivary gland. A deeper incision can be made rostral to these veins to expose the superficial temporal artery. Caudal auricular access Artery: caudal auricularartery (1.5 mm diameter); vein: caudal auricular vein (2.5–4 mm diameter). The platysma muscle and subcutaneous tissue are incised via a vertical incision caudal to the ear canal, exposing the caudal auricular vein. An incision is made in the subcutaneous tissue parallel and about 2 cm caudal to the ear canal, leading along the caudal border of the parotid gland. The caudal aspect of the parotid gland is reflected cranially, exposing the cranial auricular artery. Sublingual access Artery: lingual artery (3 mm diameter); vein: lingual vein (4 mm diameter) or sublingual vein (3–4 mm diameter). An incision is made along the digastricus muscle between the mandibular branches, followed by an incision through the mylohyoid muscle to expose the lingual vein. After retracting the hypoglossal nerve passing the hypoglossus muscle, the muscle is transected and the edges retracted to expose the lingual artery. The lingual vein is located adjacent to the lingual artery. The lingual artery is the largest of the arteries of the head region mentioned, which makes it relatively easy to locate. Lateral facial access Artery: facial artery (1.5 mm diameter); vein: facial vein (4–6 mm diameter). An incision is made along the masseter muscle and the mandibular salivary gland. The facial vein is exposed as the subcutaneous tissue is dissected. The facial artery is exposed using a dissection plane between the masseter and digastricus muscles. The dissection plane is continued to the level of the medial aspect of the mandibular salivary gland. At this point the facial artery is >1 mm in diameter. Should the facial artery be too small, the lingual artery is a relatively close alternative. Because of problems associated with the exposure and size of the facial artery and the large size of the vein, these recipient vessels are not considered ideal for free tissue transfer. Lateral cervical access Artery: common carotid artery (7 mm diameter); vein: external jugular vein (10 mm diameter). The skin and subcutaneous tissues are retracted ventrally via an incision parallel and dorsal to the crest made by the jugular vein in order to expose the external jugular vein. The brachiocephalicus and sternomastoidius muscles can be separated in a lateral to medial direction until the common carotid artery is exposed. The artery and vein of the free flap should be anastomosed using an end-to-side technique, as is always recommended when there is a relatively large difference in the size of the vessels. Because of the proximity of the vagosympathetic and recurrent nerves, this procedure should be performed carefully. Lateral shoulder access Artery: superficial cervical artery (1.5 mm diameter); vein: superficial cervical vein (3–4 mm diameter). A large incision is made starting just ventral to the acromion and extending craniodorsally towards the wing of the atlas. An incision is made between the omotranversarius and brachiocephalicus muscles and the muscles are retracted to expose the superficial cervical artery and vein within the adventitial tissue. The branches of the vessels must be ligated to allow them to be exposed properly. Forelimb recipient vessels Six surgical approaches to recipient vessels in the forelimb have been suggested.16,17 Avascular and microvascular reconstructive techniques88 89 Palmar Artery: palmar common digital artery II (no sizes mentioned); vein: cephalic vein. An incision is made from the medial aspect of the accessory carpal pad to the palmaromedial aspect of the metacarpal pad. The incision is made lateral to the vein, which lies within the superficial fascia beneath the skin. The artery can be exposed by incising the superficial fascia lateral to the cephalic vein. Distal antebrachial Artery: median artery; vein: cephalic vein. A skin incision is made just caudal and medial to the cephalic vein. The incision ends at the carpus. The cephalic vein is exposed by retracting the skin. The artery is exposed by opening the sheath of the median neurovascular bundle underneath the flexor carpi radialis tendon and the superficial digital flexor tendon. The median artery can be used in an end-to-end arterial anastomosis as the blood supply to the distal extremity will be supported by other arteries. The radial artery could be used as an alternative in larger breeds. The distal antebrachial approach should be used in cases where there is traumatic damage to the palmar vessels. Mid-antebrachial Artery: median artery; vein: cephalic vein. The cephalic vein is dissected via a skin incision on the craniomedial aspect of the mid-third of the antebrachium from superficial fascia beneath the skin. The flexor muscles are exposed by incising the deep antebrachial fascia and the median artery can be found in a neural sheath on or underneath the cranial aspect of the flexor carpi radialis muscle. Proximal antebrachial Artery: median artery; vein: cephalic vein, brachial vein. The landmark is the proximal third of the medial antebrachium. An incision is made on the craniomedial aspect of the proximal antebrachium, after which the deep antebrachial fascia is incised between the pronator teres muscle and the flexor carpi radialis muscle, separating them to expose the median artery. For the recipient vein, the brachial or cephalic veins, which lie in the subcutaneous tissue, can be used. Distal humeral Artery: brachial artery; vein: brachial vein. Avascular and microvascular reconstructive techniques The deep brachial fascia can be incised through a skin incision on the medial aspect of the distal fourth of the humeral region to expose the brachial vein along the caudal aspect of the biceps brachii muscle. The brachial vein can be retracted cranially to expose the brachial artery. Care must be taken not to damage essential nerves in the area. Mid-humeral Artery: recurrent ulnar artery; vein: recurrent ulnar vein. Access is via a skin incision made at the junction of the middle and distal thirds of the humerus just cranial to the triceps muscle. The venous branch from the biceps brachii muscle is ligated and divided if needed to expose the brachial artery. The brachial vein is retracted in order to find the recurrent ulnar artery located beneath. The recurrent ulnar vein, which is used as the recipient vein, can be found as it branches off the brachial vein. Hindlimb recipient vessels Twelve surgical approaches to recipient vessels in the hindlimb have been suggested.16,17 Plantar Artery: plantar metatarsal artery; vein: medial branch of the dorsal common digital vein. Access is via an incision in the plantar and medial aspect of the metatarsal region from the calcaneus to the metatarsal pad. The vein can be found beneath the skin on the dorsomedial aspect of the second metatarsal bone. The artery can be exposed by making an incision in the deep fascia along the medial side of the superficial and deep digital flexor tendons. The tendons should be retracted laterally to expose the interosseus group of muscles; the artery will be found between the first and second interosseus muscles. Dorsal tarsal Artery: dorsal pedal artery; vein: dorsal common digital vein or branch thereof. The dorsal pedal artery can be palpated in the dorsal tarsal area. An incision in the dorsal aspect of the tibial tarsal joint is angled slightly medially towards the junction of the second and third proximal metatarsal bones. After performing a sharp dissection medial to the common digital vein found directly beneath the skin, the short digital extensor muscles need to be separated to reveal the dorsal pedal artery. In some dogs the short digital extensor muscles are very small and difficult to identify (155–158). Cranial distal tibial Artery: cranial tibial artery; vein: cranial branch of the medial saphenous vein. The skin is incised on the cranial surface of the distal aspect of the tibia, lateral to the cranial branch of the medial saphenous vein. After dissecting the crural fascia, the long digital extensor andcranial tibial muscles/tendons are separated. The cranial tibial neurovascular bundle, which contains the cranial tibial artery, is exposed. The cranial branch of the medial saphenous vein can be exposed after dissecting it from superficial and deep fascia. Craniomedial distal tibial Artery: cranial tibial artery; vein: cranial branch of the medial saphenous vein. A skin incision is made over the craniomedial aspect of the distal tibial region just caudal to the cranial branch of the medial saphenous vein and the deep crural fascia is sharply incised. After retracting the tibialis cranialis muscle, the cranial tibial neurovascular bundle is dissected from the loose connective tissue and opened to make the cranial tibial artery available. The cranial branch of the medial saphenous vein can be used as the recipient vein. If the cranial branch of the medial saphenous vein is too small, as it can be in some smaller dogs, the lateral saphenous vein can be used. Lateral distal tibial Artery: saphenous artery; vein: lateral saphenous vein. An incision is made at the level of the distal third of the tibial region between the lateral saphenous vein and the caudal branch of the lateral saphenous vein. A prominent neurovascular bundle can be palpated along the caudal aspect of the tibia and the artery exposed. The lateral saphenous vein should be easily isolated from the subcutaneous tissues. Caudomedial distal tibial Artery: caudal branch of the saphenous artery; vein: caudal branch of the medial saphenous vein or the cranial branch of the medial saphenous vein. An incision is made over the distal and medial aspect of the tibia and the skin is reflected caudally. The neurovascular bundle can be palpated on the caudal aspect of the tibia, between the Achilles tendon and the tibia. The largest of the two veins in the bundle should be used. If it is still too small, the cranial branch of the medial saphenous vein can be used. Because of the distance between the artery and vein in this approach, they need to be separated in the pedicle on the flap in order to span the distance. Medial femorotibial Artery: saphenous artery; vein: medial saphenous vein. An incision is made over the distal third of the medial aspect of the femur. The saphenous artery and medial saphenous vein are found in the areolar tissue between the caudal head of the sartorius and gracilis muscles. An incision in the fascia between the caudal head of the muscles may be necessary. Lateral distal femoral Artery: distal caudal femoral artery; vein: distal caudal femoral vein. An incision is made over the cranial border of the distal aspect of the biceps femoris muscle. The fascia lata is incised along the cranial border of the muscle and retracted caudally. The vascular pedicle entering the distal aspect of the biceps femoris muscle can be used as the venous and arterial recipients. This procedure requires consideration of the effect on the biceps femoris muscle, part of which may be sacrificed if the blood supply is lost. Medial femoral Artery: femoral artery; vein: femoral vein. An incision is made in the mid-femoral region just cranial to the pectineus muscle. The femoral artery and vein are located just cranial to the muscle. The fascia along the caudal aspect of the caudal head of the sartorius muscle is incised and the muscle is retracted cranially, exposing the fascial sheath, which surrounds the vessels and associated femoral nerve. End-to-side anastomosis of the free flap vessels to the femoral vessels must be performed because of the large size of these recipient vessels. Medial proximal femoral Artery: proximal caudal femoral artery; vein: proximal caudal femoral vein. In contrast to the medial femoral approach, the incision is made just caudal to the pectineus muscle and cranial to the proximal half of the gracilis muscle. The vessels originate from the proximal third of the femoral artery and vein corresponding to the distal aspect of the pectineus muscle. Inguinal Artery: caudal superficial epigastric artery; vein: caudal superficial epigastric vein. An incision is made craniomedial to the origin of the pectineus muscle and lateral to the mammary chain. The mammary tissue is retracted medially and the fascia surrounding the vaginal tunic is opened to expose the caudal superficial artery and vein. Avascular and microvascular reconstructive techniques90 Proximal lateral femoral Artery: caudal gluteal artery; vein: caudal gluteal vein. A large incision is made over the greater trochanter along the axis of the femur. After incising the deep gluteal fascia, the biceps femoris and superficial gluteal muscles are retracted. The sacrotuberous ligament is incised and the gluteal vessels exposed along the ligament. Special care must be taken to avoid injury to the sciatic nerve during vessel isolation. Feline flaps Though most case reports and research focuses on free flap procedures in dogs, the use of axial flaps based on the lateral axial artery in cats has been studied.16 The mean flap size for a mature, average- sized cat was found to be 8.7 cm " 15.5 cm. The use of these flaps was successfully demonstrated in two clinical cases. Avascular and microvascular reconstructive techniques 91 155–158 (155–157) A traumatic wound that has received a rectus abdominis free flap and a skin graft over the muscle flap. The dorsal pedal artery and vein were used for the anastomosis. The skin graft was placed immediately after transfer of the muscle. (158) The wound 3 weeks postoperative after it had received a skin graft over the rectus abdominis free flap. 155 156 157 158 Conclusion/summary The advantages of microvascular flap surgery have been summed up in one study as follows: ‘versatility, reliability, vascularity and the ability to develop early one-stage corrective procedures for difficult reconstructive problems’.18 The ability to provide the flap with a blood supply through microvascular surgery not only dramatically increases the survival of flaps, it also indirectly increases healing of the underlying wound bed because of this additional beneficial circulation. However, caution is needed when considering carrying out microvascular free flap transfers. It is very important to take note of the fact that the only significant variable that influences flap survival is the experience of the surgical team performing the operation.7 This underlines the specialized nature of the surgery and the importance of experience in this field. Additionally, when it comes to exposing the recipient vessels on the recipient site, a thorough knowledge of regional anatomy and a careful and precise surgical technique are required, not only to find and expose the vessels correctly so that the procedure can be performed, but also because incorrect handling of the recipient vessels may lead to thrombosis in the anastomosis site at a later point, which can lead to severe complications.15 Finally, due to the fact that most of the techniques and anatomical dimensions presented are based on published studies and reports, which use only a limited number of animals, anatomical differences between animals may make it necessary to deviate from the precise instructions given for the procedures. This fact may lead to problems when the techniques are tried, as even within small subject groups of similarly sized dogs, anatomical differences often occur. This underlines again the importance of the surgical team having experience with microvascular flap transfers. Additionally, considering the importance of vessel size in these procedures, it is important to evaluate the fact that breed differences may require adaptations of the presented techniques. Acknowledgements This chapter is based on a thesis written by Guido Camps. The authors would like to thank Dr Dan Degner for critically reviewing the chapter and providing the photographs. Avascular and microvascular reconstructive techniques92 References 1. Kirpensteijn J, Klein WR (2006) Woundmanagement and first aid. In: The Cutting Edge: Basic Operating Skills for the Veterinary Surgeon, 1st edn. (eds J Kirpensteijn, WR Klein) Roman House Publishers, London, p. 125. 2. Hunt GB, Tisdall PLC, Liptak JM et al. (2001) Skin-fold advancement flaps for closing large proximal limb and trunk defects in dogs and cats. Vet Surg 30:440–448. 3. Harari J (2004) (ed) Small Animal Surgery Secrets. Hanley & Belfus, Philadelphia. 4. Archibald J, Cowley AJ (1974) Plastic surgery. In: Canine Surgery, 2nd edn. (ed. J Archibald) American Veterinary Publications, Santa Barbara, pp. 139–146. 5. Slatter DH (2003) Textbook of Small Animal Surgery. WB Saunders, Philadelphia. 6. Fossum TW, Duprey LP (2002) Microvascular flap transfer. In: Small Animal Surgery, 2nd edn. (eds TW Fossum, CS Hedlund, DA Hulse et al) Mosby, St. Louis, p. 182. 7. Fowler JD, Degner DA, Walshaw R et al. (1998) Microvascular free tissue transfer: results in 57 consecutive cases. Vet Surg 27:406–412. 8. Daniel RK, Williams HB (1973) The free transfer of skin flaps by microvascular anastomoses: an experimental study and a reappraisal. Plast Reconstr Surg 52:16–31. 9. Miller CW, Chang P, Bowen V (1986) Identification and transfer of free cutaneous flaps by microvascular anastomosis in the dog. Vet Surg 15:199–204. 10. Miller CW (1990) Free skin flap transfer by microvascular anastomosis. Vet Clin North Am Small Anim Pract 20:189–199. 11. Miller CC, Fowler JD, Bowen CVA et al. (1991) Experimental and clinical free cutaneous transfers in the dog. Microsurgery 12:113–117. 12. Puerto DA, Aronson LR (2004) Use of a semitendinosus myocutaneous flap for soft-tissue reconstruction of a grade IIIB open tibial fracture in a dog. Vet Surg 33:629–635. 13. Calfee III EF, Lanz OI, Degner DA et al. (2002) Microvascular free tissue transfer of the rectus abdominis muscle in dogs. Vet Surg 31:32–43. 14. Lanz OI, Broadstone RV, Martin RA et al. (2001) Effects of epidural anesthesia on microcirculatory blood flow in free medial saphenous fasciocutaneous flaps in dogs. Vet Surg 30:374–379. 15. Degner DA, Walshaw R, Fowler JD et al. (2004) Surgical approaches to recipient vessels of the head and neck for microvascular free tissue transfer in dogs. Vet Surg 33:200–208. 16. Degner DA, Walshaw R, Fowler JD et al. (2005) Surgical approaches to recipient vessels of the fore- and hindlimbs for microvascular free tissue transfer in dogs. Vet Surg 34:297–309. 17. Benzioni H, Shahar R, Yudelevich S et al. (2009) Lateral thoracic artery axial pattern flap in cats. Vet Surg 38:112–116. 18. Fowler D (2006) Distal limb and paw injuries. Vet Clin North Am Small Anim Pract 36:819–845. 93Avascular and microvascular reconstructive techniques This page intentionally left blank Chapter 5 Reconstructive techniques of the facial area and head 95 Sjef C. Buiks and Gert ter Haar • Unilateral modified nasal rotation flap • Bilateral modified nasal rotation flap • Full-thickness labial advancement flap (lower lip) • Full-thickness labial advancement flap (upper lip) • Full-thickness buccal rotation flap • Transposition skin flap for upper labial and buccal replacement • Facial artery axial pattern flap • Superficial temporal artery axial pattern flap • Caudal auricular axial pattern flap • Pedicle flap for pinnal defects Reconstructive techniques of the facial area and head96 Unilateral modified nasal rotation flap Overview A nasal rotation flap, a local subdermal flap, has been described for reconstruction of the nasal tip in humans after removal of local carcinomas. The authors have modified this flap for use in dogs and cats, so that it can be used to close wounds of different sizes and shapes in the rostrodorsal region of the nose. The following four criteria must be taken into consideration before the outlines of the flap are drawn: the type of skull (brachy - cephalic, mesocephalic or dolichocephalic), the amount of (excess) skin covering the upper lip, the location of the defect and the dimensions of the defect. In the flap description below, the defect is located dorsally at the bridge of the nose with the rostral border contacting the caudal part of the nasal plane. Larger defects can be closed using this unilateral technique or using bilateral flaps. The procedure results in a good cosmetic appearance of the wound without excess tension in the donor and recipient sites. The procedure can be further modified to include part of the dorsal nasal plane tissue in the raised flap to aid in reconstruction of lateral nasal plane defects (159, 160). Procedure A line is drawn starting at the rostral part of the defect, along the border of the tip of the nose and continuing laterally in an arch shape to meet the alar groove (161). To avoid dog ears on closure and to minimize scar formation, a triangle is formed around the distal part of the crescent-shaped line that is going to be excised (162). The flap area is then automatically outlined by the caudal part of the triangle and the medial part of the defect. To avoid a second dog ear on closure, two converging lines are drawn on the contralateral side of the nose, with the broadest part meeting the caudolateral part of the defect. The skin is incised along the predrawn lines and the two triangular-shaped skin areas are excised (163, 164). The flap area is undermined to facilitate advancement of the flap to the tip of the nose (165). One stay suture (using 2-0 absorbable monofilament suture material) only is used to manoeuvre the flap. The flap is transposed into the defect (166, 167) and the subcutaneous tissue of the flap is attached to the adjacent subcutaneous tissue in an interrupted or continuous suture pattern using 3-0 absorbable monofilament suture material (168, 169). The skin is then routinely closed (170,171). Reference Smadja J (2007) Crescentic nasojugal flap for nasal tip reconstruction. Dermatol Surg 33:76–81. Ter Haar G, Buiks SC, Kirpensteijn. Cosmetic reconstruction of a nasal plane and rostral nasal skin defect using a modified nasal rotation flap in a dog. Vet Surg, in press. 159, 160 Unilateral modified nasal rotation flap. (159) The red lines represent the incision lines for creation of the flap (marked with asterisk) and excision of Burrow’s triangles (blue, arrows), for closure of a laterodorsal nasal defect (orange with red lines). (160) After excision of Burrow’s triangles and undermining of the local skin flap (asterisk), the flap is rotated and sutured into position, yielding a cosmetic closure. 159 160 * * Reconstructive techniques of the facial area and head 97 164 Lateral view of the flap area. 165 The flap area has been undermined ready for rostromedial advancement. 166 The tip of the flap should easily reach the contralateral tip of the nose. 167 Lateral view of the flap transposed into position. 168 The subcutaneous tissue of the flap is sutured to the adjacent subcutaneous tissue. 169 Lateral view of the flap with the subcutaneous tissues apposed. 170 Closure of the skin, dorsal view. Note the absence of dog ears. 171 Left lateral view after skin closure and flap completion. 162 Lateral view of the flap area. The triangle will be excised to avoid a dog ear on closure. 163 Both redundant skin triangles have been excised. 161 162 163 164 165 166 167 168 169 170 171 161 Dorsal view on the surgery site. The shaded area will be removed to create the defect. Reconstructive techniques of the facial area and head98 Bilateral modified nasal rotation flap Overview Bilateral use of a modified nasal rotation flap allows for closure of larger defects of the skin of the rostral nose in dogs and cats without creating the asymmetry that usually results from advancing a large amount of local tissue in this area. The same criteria as described for the unilateral technique (see p.96) must be taken into consideration before the outlines of the flap are drawn. There are two variations of the bilateral flap technique: • Performing the techniquebilaterally exactly as described for the unilateral technique allows for closure of relatively long, but not very wide, defects where both flaps meet in the midline. • For closing defects that are relatively short but wide, the flaps can be advanced and undermined further so that they cross the midline. One side can be used to close the more rostral part of the defect, while the second part is used to close the caudal part (172, 173). Procedure The incision lines needed to create the bilateral nasal rotation flaps are outlined using the same method as for the unilateral procedure (174). The predrawn lines are then incised and the two triangle-shaped skin areas are excised (175). After placing tag sutures in both flaps, they are undermined to facilitate advancement of the skin over the bridge of the nose (176). The flaps are undermined until they can be rotated into place without tension. Both crescentic defects are then filled (177). In order to avoid necrosis of the end of the flap, the ends can be trimmed with scissors or a scalpel (178). The subcutaneous tissue (179) and the skin (180) are closed routinely. Reference Smadja J (2007) Crescentic nasojugal flap for nasal tip reconstruction. Dermatol Surg 33:76–81. 172,173 Bilateral modified nasal rotation flap. (172) The red lines represent the incision lines for creation of two rotation flaps (A + B) after excision of Burrow’s triangles (blue, arrows) to close a large oval dorsal nasal midline defect (orange). (173) The two raised flaps are rotated into position to fill the defect. Note that after rotation of the flaps and closure, the formation of dog ears is prevented by the previous excision of Burrow’s triangles. 174172 173 174 The excision area of the defect and the incision and excision lines of the bilateral crescentic nasojugal flaps are outlined with blue ink. Reconstructive techniques of the facial area and head 99 175 The defect has been excised, as well as the triangles of skin necessary to rotate the bilateral flap into the defect. 176 Stay sutures are placed in both flaps to aid undermining of the tissues and rotation into the defect. 177 Both flaps have been rotated into position. In case of relatively short but wide defects, the flaps are rotated to fill the rostral and caudal part of the defect. 178 The pointed ends of the flap are trimmed. 179 The flaps are sutured in place starting with closure of the subcutis in an interrupted suture pattern. 180 The completed bilateral modified nasal rotation flap after closure of the skin with interrupted nonabsorbable sutures is shown. 175 176 177 178 179 180 Reconstructive techniques of the facial area and head100 Full-thickness labial advancement flap (lower lip) Overview This technique is used to close rostral defects of the lower lip. The inferior labial artery and vein provide the blood supply to the lower lip and should be preserved. The lower lip is easier to mobilize than the upper lip. As a result, the skin incision required for rostral advancement is only a few centimetres, even in large defects. Procedure A full-thickness labial excision of the tumour (in this case), with clear margins, is performed (181). A skin incision of variable length is created to advance the lower lip rostrally (182). The mucosa of the lower lip is incised a few millimetres from the gingival border (183). The flap is undermined and elevated while preserving the vessels to the desired length. Rostral traction is applied to the lower lip in order to close the defect without tension (184). The mucosal incision is closed in either an interrupted or continuous pattern using absorbable monofilament suture material (185, 186). The submucosa/subcutis is closed with interrupted sutures using absorbable monofilament suture material. If necessary, a Penrose drain is used to control dead space (187). The skin is sutured with nonabsorbable monofilament suture material (188). 181 Full-thickness labial excision of a tumour of the lower lip has been performed. 182 A skin incision is made caudally from the caudoventral aspect of the wound. References Degner DA (2007) Facial reconstructive surgery. Clin Tech Small Anim Pract 22:82–88. Pavletic MM (1990) Reconstructive surgery of the lips and cheek. Vet Clin North Am Small Anim Pract 20:201–226. Pavletic MM (2010) Atlas of Small Animal Wound Management and Reconstructive Surgery, 3rd edn. Wiley–Blackwell, Ames, pp.456–457. 181 182 Reconstructive techniques of the facial area and head 101 183 A full-thickness flap is created by undermining the tissue while preserving a 2 mm strip of mucosa on the gingival border to facilitate suturing at a later stage. 184 Rostral tension is applied to the flap to determine the appropriate size. 185 The mucosa is sutured first with a stay suture, starting rostrally. 186 The suturing of the mucosa has been completed. 187 Closure of the subcutis has been performed with absorbable monofilament suture material. 188 The skin has been sutured with nonabsorbable monofilament suture material. 183 184 185 186 187 188 Reconstructive techniques of the facial area and head102 Full-thickness labial advancement flap (upper lip) Overview A labial advancement flap entails complete elevation of the entire thickness of the upper lip to maximize its advancement into rostral labial defects. The blood supply is dependent on the superior labial artery and vein. This flap is especially suitable for defects involving the rostral third of the upper lip. When necessary, the flap can be combined with partial maxillectomy. Retraction of the flap can cause unilateral distortion of the nasal planum, but this usually subsides over 1–2 weeks. Procedure A full-thickness rectangular excision of the tumour of the upper lip (in this case) is performed and a skin incision drawn in the caudal upper lip to allow for advancement of the lip over the desired length (189). The upper lip is incised down to the mucosa. A 5 mm strip of mucosa should be left along the gingival border (190). The flap is carefully dissected and advanced rostrally without compromising the blood supply at the base of the flap (191). A wedge-shaped area is trimmed from the rostral border of the flap so that the entire flap conforms more accurately to the curvature of the opposing labial margin (192). The mucosa is closed with absorbable sutures in a simple interrupted pattern (193, 194). The skin is closed with interrupted sutures using nonabsorbable monofilament suture material (195). References Degner DA (2007) Facial reconstructive surgery. Clin Tech Small Anim Pract 22:82–88. Pavletic MM (1990) Reconstructive surgery of the lips and cheek. Vet Clin North Am Small Anim Pract 20:201–226. Pavletic MM (2010) Atlas of Small Animal Wound Management and Reconstructive Surgery, 3rd edn. Wiley–Blackwell, Ames, pp. 454–455. 189 A full-thickness rectangular excision of a tumour of the rostral upper lip has been performed. The labial advancement flap has been outlined with blue ink. 190 The flap is incised down to the mucosa. 189 190 Reconstructive techniques of the facial area and head 103 191 The flap is undermined until advancement can be done without tension. 192 Part of the rostral border of the flap is trimmed to allow for better cosmesis. 193 Closure of the mucosal surface is started. 194 Closure of the mucosal surface is completed. 195 The skin is closed in a simple interrupted pattern with nonabsorbable suture material. 191 192 193 194 195 Reconstructive techniques of the facial area and head104 Full-thickness buccal rotation flap Overview A full-thickness buccal rotation flap is a variation of the labial advancement flap. It is primarily indicated after resection of large parts of the upper lip. The buccal rotation technique will advance the labial commissure rostrally, which may result in mild facial asymmetry. Procedure Lip tumours should be removed with wide margins and wounds debrided (196). The remaining caudal labial marginand cheek can now be grasped, rotated and stretched rostrally towards the rostrodorsal defect with a suture (197, 198). A portion of the lip margin of the rotation flap is trimmed before apposition to the skin of the rostral lip (199). The respective skin borders of the flap can now be apposed to the remaining labial margin (200, 201). The oral mucosa is closed in an interrupted or continuous suture pattern (202) and the skin is apposed with interrupted sutures (203). References Degner DA (2007) Facial reconstructive surgery. Clin Tech Small Anim Pract 22:82–88. Pavletic MM (1990) Reconstructive surgery of the lips and cheek. Vet Clin North Am Small Anim Pract 20:201–226. Pavletic MM (2010) Atlas of Small Animal Wound Management and Reconstructive Surgery, 3rd edn. Wiley–Blackwell, Ames, pp. 458–459. 196 Full-thickness resection of a tumor has been carried out, resulting in a large rectangular defect. 197 A suture is placed in the caudal labial margin to help rotate and advance the flap towards the dorsorostral part of the defect. 196 197 Reconstructive techniques of the facial area and head 105 198 After tightening the suture, an estimation of the amount of lip border that has to be trimmed can be made. 199 A portion of the lip margin is trimmed with scissors or a scalpel. 200 The first step in closure is apposing the remaining labial borders. 201 The first skin suture is tightened, after which the remainder of the defect is closed. 203 The end result after closing the subcutis in a continuous pattern and closing the skin with interrupted sutures is shown. 202 The oral mucosa is closed with interrupted sutures, starting ventrally. The ventral part of the closed Y-defect is shown. The remainder of the defect is closed in a similar manner. 198 199 200 201 202 203 Reconstructive techniques of the facial area and head106 Transposition skin flap for upper labial and buccal replacement Overview Skin flap replacement of the lip and upper cheek, based on a facial artery axial pattern flap (see p. 108) is only recommended when the defect is too large to be closed by other techniques. While the skin serves as an adequate replacement for the oral mucosa, flaps using oral mucosa are preferable whenever possible. Procedure A wide resection using 75% of the upper lip and adjacent cheek is performed (204). A transposition flap is outlined on the cheek adjacent to the defect. The width of the flap should be approximately twice the width of the defect, since part of the flap will be used to replace the mucosal defect. The base of the flap is aligned with the lower buccal edge of the defect (205). The skin portion of the flap is incised and then carefully undermined beneath the panniculus muscle to the level of the base of the flap near the defect (206). The dorsal border of the flap is sutured to the remaining mucosa of the upper lip in a simple interrupted pattern with absorbable suture material (207). The skin flap is folded onto itself and the subcutaneous/submucosal tissues are sutured with interrupted absorbable monofilament material (over a Penrose drain when necessary) (208, 209). The skin is apposed with interrupted sutures (210). References Pavletic MM (1990) Reconstructive surgery of the lips and cheek. Vet Clin North Am Small Anim Pract 20:201–226. Pavletic MM (2010) Atlas of Small Animal Wound Management and Reconstructive Surgery, 3rd edn. Wiley–Blackwell, Ames, pp. 468–469. 204 A full-thickness resection of the upper lip and adjacent cheek has been performed. 205 A transposition flap is outlined on the skin with blue ink. 204 205 Reconstructive techniques of the facial area and head 107 206 The skin flap is undermined towards the base of the flap at the level of the defect. 207 The replacement flap has been sutured to the remaining upper lip mucosa. 208 The skin flap is folded onto itself. 209 The subcutaneous and submucosal tissues have been apposed. 210 The skin has been closed in an interrupted pattern with nonabsorbable suture material. 206 207 208 209 210 Reconstructive techniques of the facial area and head108 Facial artery axial pattern flap Overview A facial artery axial pattern flap can be used to cover defects involving the rostral and lateral nasal regions and the maxilla. The base of the flap is located at the commissure of the lip and is therefore perfused by the superior and inferior labial arteries. A cutaneous branch of the angularis artery runs between the superior and inferior labial arteries and meets the cutaneous branches of the masseteric artery and the transverse facial artery at the dorsal extent of the flap. The caudal border of the flap is defined by the lateral aspect of the first cervical vertebra (atlas). Sufficient skin is usually harvested if the flap is extended to the level of the vertical ear canal. This also reduces the risk of necrosis of the tip of the flap. The lateral borders of the flap are the caudal mandible ventrally and the ventral aspect of the zygomatic arch dorsally. In the cat, the viability of an axial pattern flap based on the facial artery, with similar dimensions to the flap, has recently been demonstrated (211, 212). Procedure The outline of the flap is drawn using the following landmarks: the lateral aspect of the atlas, the ventral margin of the caudal mandible and the ventral aspect of the zygomatic arch (213). The skin is incised as outlined and then undermined (214). The flap is transposed into the defect (215). The remaining labial mucosa is attached to the maxillary gingiva in either an interrupted or continuous pattern using absorbable monofilament suture material (216). The subcutis of the most distal corners of the flap is sutured to the subcutaneous tissue of its new location using absorbable interrupted sutures (217). The remaining subcutaneous tissue is then sutured (218). A Penrose drain can be used if needed. The skin is closed routinely using nonabsorbable monofilament suture material (219). References Milgram J, Weiser M, Kelmer E et al. (2011) Axial pattern flap based on a cutaneous branch of the facial artery in cats. Vet Surg 40:347–351. Pavletic MM (1990) Reconstructive surgery of the lips and cheek. Vet Clin North Am Small Anim Pract 20:201–226. Pavletic MM (2010) Atlas of Small Animal Wound Management and Reconstructive Surgery, 3rd edn. Wiley–Blackwell, Ames, pp. 468–469. Yates G, Landon B, Edwards G (2008) Investigation and clinical application of a novel axial pattern flap for nasal and facial reconstruction in the dog. Aust Vet J 85:113–118. 211, 212 Schematic representation of the facial artery axial pattern flap. The coloured part of the dog depicts the estimated area that can be reached by the flap. 212211 Reconstructive techniques of the facial area and head 109 213 The boundaries of the axial pattern flap are drawn. 214 The flap is incised along the dotted outline. 215 The flap is rotated into position. 216 The labial mucosa is attached to the gingiva. 217 The primary closure of the subcutaneous tissue has been performed. 218 The flap is sutured to its new location with interrupted sutures using absorbable suture material. 219 A lateral view following closure of the skin. 213 214 215 216 217 218 219 Reconstructive techniques of the facial area and head110 Superficial temporal artery axial pattern flap Overview This axial pattern flap has been described for use in both dogs and cats. The vascular supply consists of a cutaneous branch of the superficial temporal artery. The subdermal plexus that lies both superficial and deep to the frontal muscle is incorporated into the flap. The flap is used to cover defects involving the maxilla and the maxillofacial area. The anatomical boundary of the base of the flap is determined by the lateral orbital rim. The width of the flap is limited rostrally by the eye and caudally by the ear, therefore the width of the flap is equal to the length of the zygomatic arch. In brachycephalic breeds, the amount of skinthat can be harvested is limited. The length of the flap is limited to the dorsal orbital rim of the contralateral eye. Extending the flap beyond this point has been shown to result in necrosis of the distal end of the flap (220, 221). Procedure Two parallel lines are drawn to outline the width of the flap according to its boundaries. The base of the flap is located at the level of the dorsal orbital rim. This can be extended if a longer flap is needed to cover a more rostral defect. After the lines have been extended (if necessary) to the dorsal orbital rim of the contralateral eye, they are connected in a straight line (222). The flap is incised and bluntly dissected from the underlying tissue, underneath the frontal muscle (223). The flap is then transposed onto the site of the defect using stay sutures. If tension is excessive, the most rostral incision of the flap above the eye can be extended (224). The flap is sutured to the periosteum on the midpoint of the convex side of the flap. This technique prevents there being an abundance of skin on the concave side of the flap covering the eye (225). Alternatively, the dog ear can be removed using a Burrow’s triangle (see H-plasty, p.118). The subcutaneous tissues of the flap and the donor site are closed in an interrupted or continuous pattern using absorbable monofilament suture material (226). The skin of the flap and the donor site are closed routinely with interrupted sutures using nonabsorbable monofilament suture material (227). References Fahie MA, Smith MM (1997) Axial pattern flap based on the superficial temporal artery in cats: an experimental study. Vet Surg 26:86–89. Fahie MA, Smith MM (1999) Axial pattern flap based on the cutaneous branch of the superficial temporal artery in dogs: an experimental study and case report. Vet Surg 28:141–147. Fahie MA, Smith BJ, Ballard JB et al. (1998) Regional peripheral vascular supply based on the superficial temporal artery in dogs and cats. Anat Histol Embryol 27:205–208. Hedlund CS (2002) Surgery of the integument. In: Small Animal Surgery, 2nd edn. (eds TW Fossum, CS Hedlund, DA Hulse et al.) Mosby, St. Louis, pp. 134–228. Pavletic MM (2010) Atlas of Small Animal Wound Management and Reconstructive Surgery, 3rd edn. Wiley–Blackwell, Ames, pp. 398–399. Reconstructive techniques of the facial area and head 111 220, 221 Schematic representation of the superficial temporal artery axial pattern flap. The coloured part of the dog depicts the estimated area that can be reached by the flap. 222 A dorsal view of the defect and the borders of the flap. 223 After incising the flap, a bridge has automatically been created between the defect and the donor site. 224 Tension in the flap is assessed by rotating the flap into the defect. 225 In order to prevent the creation of dog ears and abundant skin in the orbital region of the eye, the flap is sutured to the periosteum. 226 The subcutis is closed to relieve tension using absorbable monofilament material. 227 The final appearance of the reconstructed defect after routine skin closure is shown. 220 221 222 223 224 225 226 227 Reconstructive techniques of the facial area and head112 Caudal auricular axial pattern flap Overview The caudal auricular axial pattern flap, also known as the platysma myocutaneous flap, is used to reconstruct defects in the neck and caudodorsal part of the skull. The flap can be extended rostrally to cover defects in the dorsal orbital area. This flap is also used to cover defects ventral to the orbit and after eye enucleation. The base of the flap is centred over the lateral wing of the first cervical vertebra (atlas). The branches of the caudal auricular artery and vein are directed caudodorsally. The caudal auricular artery is located approximately 1 cm caudal to the base of the scutiform cartilage of the auricle (228–230). Procedure With the animal in lateral recumbency, the scapula should be positioned perpendicular to the trunk. This can be done by extending the forelimb and securing it to the table if necessary. The width of the flap should correspond to the width of the defect. Two parallel lines are drawn beginning just ventral of the base of the ear and extending to the cranial aspect of the scapula. The distance between the lines determines the width of the flap (231, 232). The flap is then positioned in the mid-section of the cervical region. The two lines are connected at the level of the scapula (232). A defect is created by removing a tumour or debriding a wound (233). The skin flap is incised along the predrawn lines (234). The skin is then undermined and elevated, taking care to preserve the cutaneous vessels that enter the flap between the vertical ear canal and the wing of the atlas. The skin should be undermined deep to the platysma muscle (sphincter colli superficialis). A bridging incision is used to connect the donor and recipient sites (235). The flap is rotated dorsally and rostrally into the defect (236). The flap is then sutured into place in two layers and the donor site is closed using two layers. Absorbable monofilament suture material should be used for the subcutis and nonabsorbable mono filament suture material or skin staples for the skin (237, 238). References Hedlund CS (2002) Surgery of the integument. In: Small Animal Surgery, 2nd edn. (eds TW Fossum, CS Hedlund, DA Hulse et al.) Mosby, St. Louis, pp. 134–228. Pavletic MM (2010) Atlas of Small Animal Wound Management and Reconstructive Surgery, 3rd edn. Wiley–Blackwell, Ames, pp. 396–397. Pope ER (2006) Head and facial wounds in dogs and cats. Vet Clin North Am Small Anim Pract 36:793–817. Smith MM, Payne JT, Moon ML et al. (1991) Axial pattern flap based on the caudal auricular artery in dogs. Am J Vet Res 52:922–925. Stiles J, Townsend W, Willis M et al. (2003) Use of a caudal auricular axial pattern flap in three cats and one dog following orbital exenteration. Vet Ophthalmol 6:121–126. 228–230 Schematic representation of the caudal auricular artery axial pattern flap. The coloured part of the dog depicts the estimated area that can be reached by the flap. 228 230229 Reconstructive techniques of the facial area and head 113 231 A dorsal view of the outlined defect (shaded area). 232 Outline of the flap in the mid-section of the cervical region. 233 A defect has been created. 234 The borders of the flap have been incised. 231 232 233 234 237 The subcutaneous tissues of the flap are sutured to the subcutis of the recipient site. 238 The subcutaneous tissues of the donor and recipient sites have been closed over a Penrose drain. The skin has been closed using staples. 237 238 235 After undermining the flap, a bridging incision is made. 236 The flap is rotated into the defect. 235 236 Reconstructive techniques of the facial area and head114 Pedicle flap for pinnal defects Overview This is a distant flap used to reconstruct defects on the convex side of the pinna. Full-thickness defects and/or defects on the concave side can be reconstructed using different techniques. Healing by second intention is the first option. The second option is to sever the pedicle flap created for coverage of the convex side from the donor site at its base. A second pedicle flap from the dorsal part of the head can then be sutured onto the concave side of the defect. The third option is to incise the base of the pedicle flap created for coverage of the convex side so that it can be folded over the caudal rim of the pinna. It is subsequently sutured in place on the concave side of the pinna. Vascular obstruction and necrosis are more likely to occur using the latter technique. The second technique is described below. Procedure The pinna with the defect is placed against the donor site (i.e. the lateral aspect of the neck) (239). An incision is made in the donor site to match the shape of the pinnal defect. The incisions are extended approximately 5 mm to 1 cm and the flap is undermined (240). The flap is sutured to the skinon the convex surface of the pinna using interrupted sutures of nonabsorbable monofilament suture material (241). A nonadherent bandage is used to cover the wound and ear. The bandage should be changed regularly for 10–14 days. The flap is then incised at its base (242). The sutures are removed and the steps described above are repeated 10–14 days after the initial procedure to cover the defect on the concave surface of the ear. The donor site will now be the dorsum of the head (243, 244). The bandage is changed regularly, the sutures removed 239 A full-thickness defect of the left pinna is shown. 240 The flap outline matches the boundaries of the defect. The incisions are extended for 5 mm on the skin of the neck. 241 After undermining the flap, it is sutured to the skin of the pinna. 242 The flap is cut at its base and the sutures are removed after 10–14 days. 239 240 241 242 Reconstructive techniques of the facial area and head 115 after 10–14 days and the flap incised at its base (245). The donor site is closed routinely (246). References Fossum TW (2007) Surgery of the ear. In: Small Animal Surgery, 3rd edn. (eds TW Fossum, CS Hedlund, AL Johnson et al.) Mosby Elsevier, St. Louis, pp. 289–316. Henderson RA, Horne R (2003) Pinna. In: Textbook of Small Animal Surgery, 3rd edn. (ed D Slatter) WB Saunders, Philadelphia, pp. 1737–1746. Pavletic MM (2010) Atlas of Small Animal Wound Management and Reconstructive Surgery, 3rd edn. Wiley–Blackwell, Ames, pp. 666–667. Swaim SF, Henderson RA (1997) Small Animal Wound Management, 2nd edn. Williams & Wilkins, Philadelphia, pp. 143–275. 243 The second flap is outlined on the dorsum of the head. 244 The flap is sutured to the concave side of the pinna, on top of the former flap. 245 The flap is incised at its base after 10–14 days. 246 Closure of the donor site is shown. 243 244 245 246 This page intentionally left blank • H-plasty • Z-plasty • Semicircular skin flap • Rhomboid flap • Modified cross lid flap • Lip-to-eye mucocutaneous subdermal plexus rotating flap • Superficial temporal artery axial pattern flap for reconstruction of the upper eyelid • Entropion repair and the arrowhead method for correction of lateral canthal entropion involving the upper and lower eyelid • Stades technique for correction of upper eyelid entropion/trichiasis • Munger–Carter flap adaptation of the Kuhnt–Szymanowski/Fox–Smith procedure for correction of lower eyelid ectropion and macroblepharon in dogs 117 Chapter 6 Reconstructive techniques of the eyelids Rick F. Sanchez techniques such as autologous conjunctival trans - plants, pedicles or autologous buccal mucosal trans - plants are also performed. Procedure The patient is positioned in sternal recumbency with the head slightly elevated and turned to give good exposure of the surgical field. The lesion to be removed is highlighted in the skin of the lower eyelid using blue ink (247). The lesion is then excised, creating a large, full-thickness eyelid defect (248). The incision path for the H-plasty consists of two slightly diverging lines that extend from the ventral 118 H-plasty Overview This is a relatively simple technique that can be used to reconstruct a very large portion of the upper or lower eyelid, including parts of the lateral canthus. Superficial eyelid defects or full-thickness defects may be reconstructed using this technique. Recon - struction of large defects of the upper eyelid may result in impairment of the blink response. In addition, as peripheral skin is used, trichiasis is a potential complication. When repairing large full- thickness defects, the surgeon must remember that no conjunctival lining is provided unless additional 247 The lesion to be removed is shown in blue ink on the lower eyelid. 249 The incision for the H-plasty is shown in blue ink. 248 The lesion is removed, creating a large full-thickness defect. 250 The Burrow’s triangles of skin are removed from each side of the incision path. Reconstructive techniques of the eyelids 247 248 249 250 sides of the defect for a length approximately one and a half times the length of the defect. Two Burrow’s triangles are incorporated into each in - cision line, with the point of each triangle being away from the incision line. The side of the triangle that runs along the incision line is at least the same length as the distance the flap must travel to cover the defect (249). The triangles are removed and the flap is dissected with care from the tissues below using scissors. The surgeon should ensure that the flap is capable of moving freely and will cover the defect with no tension (250–252). The flap is secured into position by placing sutures in the angles created by the collapsed triangles and also half way along the main vertical incision of the graft. Positioning of the graft should allow for at least 1 mm of graft to protrude from the eyelid margin into the inter palpebral fissure (253). The flap is now secured at the palpebral edge in two layers. First, a suture of absorbable material is placed in the subcutaneous plane with a buried knot. The first bite (as shown in 254) is taken in the right side of the graft as it travels in a proximal to distal direction. The needle is then redirected to engage the opposite side of the wound and create a bite that travels in the opposite direction. 119 253 The first sutures are placed in the skin. 252 The graft covers the defect without tension.251 The flap should move easily. 251 252 253 254 The first deep bite is taken in the graft side in order to create a buried knot. 254 Reconstructive techniques of the eyelids This creates a loop of suture that places the knot in the proximal part of the incision path away from the surface. A more detailed view can be seen under Z-plasty (266–279) and in the diagrams provided in the section on the rhomboid flap (285, 286). Before closure, the surgeon must ensure that 1 mm of grafted tissue will protrude into the inter - palpebral aperture, over the eye. Once the knot is tied, the long end of the suture material may be used to close the sub cutaneous layer with a simple continuous pattern that is extended to where the surgeon placed the first skin suture. At this point a second buried knot is created and the suture is cut (255). A full description of how this is done can be found under Z-plasty (p. 121). The surgeon must ensure that the buried knot does not protrude into the space between the eyelid and the eye or onto the skin surface. In thin eyelids it may not be possible to close the subcutaneous layer separately from the cutaneous layer. The skin near the eyelid edge is then sutured in a simple continuous or simple interrupted suture pattern using absorbable suture material and the remainder of the surgical wound is closed with simple interrupted sutures of nonabsorbable suture material (256, 257). References Stades F, Gelatt K (2007) Eyelid surgery. In: Veterinary Ophthalmology, 4th edn. (ed K Gelatt) Blackwell Publishing, Ames, pp. 563–617. van der Woerdt A (2004) Adnexal surgery in dogs and cats. Vet Ophthalmol 7:284–90. 120 255 The second bite is taken in the opposite side of the wound. 256 The skin is sutured in a simple interrupted pattern using nonabsorbable suture material. 257 The free edge of the graft should protrude approximately 1 mm into the interpalpebral fissure. 255 256 257 Reconstructive techniques of the eyelids Z-plasty Overview This sliding flap technique is very useful for the reconstruction of defects of the lateral aspect of the upper or lower eyelid and, therefore, part of the lateral canthus. It is a simple and elegant technique that ensures repair of a relatively large defect with minimal wound tension. As with other sliding graft techniques, trichiasis may result. Procedure The patient is positioned in sternal recumbency with the head slightly elevated and turned to give good exposure of the surgical field. The lesion to be removed is highlightedin the skin using blue ink (258). The lesion is then excised, creating a large, full-thickness eyelid defect (259). Carefully planned Burrow’s triangles are marked on the skin with blue ink (260). One triangle is positioned next to the lateral canthus and the other is posi tioned in the uppermost corner of the defect to be closed. The upper triangle is positioned so that the angle in contact with the main incision line is pointing ventrally and the triangle in the lateral canthus is positioned so that the angle that contacts the main incision line is pointing dorsally. 121 258 The lesion to be removed is marked in blue ink. 259 The lesion is excised, creating a full-thickness defect. 260 Burrow´s triangles are carefully planned as shown. 259 258 260 Reconstructive techniques of the eyelids The planned triangle path is incised with a scalpel and then removed with scissors (261, 262). The skin to be advanced should be carefully undermined with scissors so that the graft encounters little resistance when sliding into the wound. The graft is moved in such a way that both Burrow’s triangles are closed (263). The first skin sutures help relieve any tension left in the tissue, which should be minimal, and they are placed in the centre of each 122 263 After careful tissue dissection, the defect should close easily and with minimal wound tension. 264 Skin sutures are placed in the middle of each incision line on either side of the eyelids. 261 Incisions are made into the skin following the planned outline. 262 The incised triangles are removed. incision line on either side of each eyelid. This should ensure that the edge of the graft that recreates the eyelid margin is protruding into the interpalpebral aperture over the eye for at least 1 mm to allow for graft shrinkage. The distal part of each of the incision lines may be closed after this (264, 265). The subcutaneous layer of the recreated eyelid margin is sutured next using absorbable suture material. The needle bites are placed so that 261 262 263 264 Reconstructive techniques of the eyelids 123 the knot is buried within the skin. As this is a ‘holding’ suture, it must include the tarsal plate whenever possible. The first needle bite is placed into the upper eyelid. It travels parallel to the skin surface, starting 3 mm into the wound, goes through the tarsal plate and exits near the eyelid margin. The needle is then redirected into the advanced skin graft, entering 1 mm away from the edge of the graft; this ensures that the grafted skin will protrude 1 mm into the palpebral aperture. The needle then travels parallel to the skin and exits 3 mm from the incision line (266–268). The suture loop thus formed allows for a buried knot to be created once the suture is tied. After this, the long end of the suture material may be used to close the subcutaneous layer with a simple continuous pattern that is extended to where the first skin suture was placed. 267 The needle is directed onto the other side of the wound, ensuring that it enters the graft 1 mm away from its edge and exits 3 mm from the wound. 268 The suture forms a loop that creates a buried knot when tied. 265 The distal part of each incision line can be closed at this stage. 266 Creation of a buried knot. A first bite is taken into the upper eyelid 3 mm from the wound and exiting next to the edge of the eyelid. The needle must travel parallel to the skin and into the tarsal plate. 265 266 268267 Reconstructive techniques of the eyelids At this point a second buried knot is created and the suture is cut. The surgeon must ensure that buried knots never protrude into the space between the eyelid and the eye or onto the skin surface. In thin eyelids it may not be possible to close the subcutaneous layer separately from the cutaneous layer (269, 270). The skin near the eyelid edge is then sutured using a simple continuous or simple interrupted suture pattern of absorbable material, and the remainder of the surgical wound is closed with simple interrupted sutures of nonabsorbable material (271). Absorbable multifilament suture material is preferred when in close proximity to the eye be cause of the softer nature of the ends of the sutures. The wound of the lower eyelid margin is closed in a similar manner. The first bite is taken into the eyelid side of the wound. It travels from 3 mm from the wound margin, through the tarsal plate, parallel to the skin, and exits close to the edge of the eyelid. The needle is then redirected into the edge of the graft. It enters 1 mm away from the graft’s edge; 124 271 The remainder of the skin incision is closed with simple interrupted sutures. Absorbable multifilament suture material is preferred when in close proximity to the eye due to the softer nature of the suture ends. 272 A first bite is taken into the lower eyelid 3 mm into the wound and exiting next to the edge of the eyelid. The needle must travel parallel to the skin and into the tarsal plate. 269 Only the short end of the suture is cut, leaving the long end available to close the subcutaneous layer. 270 A buried knot is tied and the suture is cut. 269 270 271 272 Reconstructive techniques of the eyelids this ensures that the grafted skin will protrude 1 mm into the palpebral aperture. The needle then travels parallel to the skin and exits 3 mm from the incision line (272, 273). The resulting suture loop allows for a buried knot to be created once the suture is tied. After this, the long end of the suture material may be used to close the subcutaneous layer separately from the cutaneous layer, as was done with the upper eyelid, provided the eyelid thickness allows for a two-layer closure (274, 275). The skin near the eyelid edge is then sutured using a simple interrupted suture pattern of absorbable material and the remainder of the surgical wound is closed in a similar manner with nonabsorbable material (276). References Stades F, Gelatt K (2007) Eyelid surgery. In: Veterinary Ophthalmology, 4th edn. (ed K Gelatt) Blackwell Publishing, Ames, pp. 563–617. van der Woerdt A (2004) Adnexal surgery in dogs and cats. Vet Ophthalmol 7:284–290. 125 275 Only the short end of the suture is cut, leaving the long end available to close the subcutaneous layer. 276 The remainder of the skin incision is closed with simple interrupted sutures. Absorbable multifilament suture material is preferred when in close proximity to the eye due to the softer nature of the suture ends. 273 The needle is directed onto the other side of the wound, ensuring it enters the graft 1 mm away from its edge and exits 3 mm into the wound. 274 The suture forms a loop that creates a buried knot when tied. 273 274 275 276 Reconstructive techniques of the eyelids Semicircular skin flap Overview This is a relatively challenging technique that uses both rotation and sliding of skin. It may be used to repair defects of the upper or lower eyelids that are between 30% and 60% of the eyelid length; however, reconstruction of large defects of the upper eyelid may result in some impairment of the blink response. In addition, as peripheral skin is used, trichiasis is a potential complication. The radius of the circular incision should be twice the length of the defect to be closed and the flap should always rotate from a lateral to a medial direction. To facilitate movement of the flap, a Burrow’s triangle is removed from the distal end of the incision and the flap is undermined with care. Procedure The patient is positioned in sternal recumbency with the head slightly elevated and turned to give good exposure of the surgical field. A curved incision with a radius that is twice the size of the defect is planned starting at the apex of the triangle. The incision outline extends to the facial skin lateral to the lesion (277). A Burrow’s triangle is excised at the end of the incision to allow the skin and orbicularis oculi muscle flap to slide medially once the flap has been undermined(278). The flap is undermined and then rotated medially into the defect. The wound created by the excision of the Burrow’s triangle should close with minimal ten - sion, while the corner of the triangle at the end of the extended curved incision collapses to meet the other side of the wound (279). The first suture is placed at this point of collapse. A second suture is then placed one-third of the way between the first suture and the eyelid margin, followed by a third suture, which is placed two-thirds of the way to the eyelid margin. These sutures should relieve any residual flap tension while at the same time allowing the new eyelid margin to protrude 1–2 mm into the palpebral aperture to compensate for flap shrinkage (280). The eyelid margin is sutured using an internal buried knot in the shape of an inverted vertical mattress suture. The needle is introduced into the flap side 5 mm from the wound’s edge and exits 1 mm away from the edge of the graft before crossing over onto the eyelid, where it enters just below the eyelid edge and exits 4 mm into the wound so as to mirror the opposite suture path (281). The suture is tied and the long end used to suture the muscle–stroma–conjunctival layers at either side of the wound up to the area where the third skin suture was placed (282). The subcutis in between the initial skin sutures is sutured, if necessary, with absorbable material. The rest of the skin is closed with simple interrupted absorbable sutures (283, 284). References Pellicane CP, Meek LA, Brooks DE et al. (1994) Eyelid reconstruction in five dogs by the semicircular flap technique. Vet Comp Ophthalmol 4:93–103. Stades F, Gelatt K (2007) Eyelid surgery. In: Veterinary Ophthalmology, 4th edn. (ed K Gelatt) Blackwell Publishing, Ames, pp. 563–617. 126 277 The outline of the incision for the semicircular flap, starting at the ventral edge of a defect of the lower eyelid and ending in a Burrow’s triangle, is shown. 278 The incision has been made and the Burrow’s triangle excised in preparation for undermining of the flap. 277 278 Reconstructive techniques of the eyelids 127 279 The flap is rotated medially and the Burrow’s triangle collapses in the process. 280 The placement of the first three skin sutures is shown. This minimizes any residual tension on the flap prior to sutur - ing its edge onto the eyelid margin. 281 An inverted vertical mattress suture is used to appose the flap to the eyelid edge, which closes the defect. 282 The long end of the suture is used to complete the deep layer closure with a simple continuous suture pattern. 283 The subcutaneous tissues of the donor and recipient site are apposed if needed with interrupted sutures placed between the first three skin sutures. 284 The skin is closed routinely. 279 280 281 284283 282 Reconstructive techniques of the eyelids RHOMBOID FLAP Overview This technique has been described in humans to reconstruct skin defects near or directly involving the medial canthus. Skin in this region is adhered to the underlying tissues, making flaps much less mobile. The method described in this book has been modified to involve the medial canthus and recon - struct the upper punctum after it has been removed during mass resection. It also makes use of a tarsal plate suture (285) and a figure-of-eight suture (286). Reconstruction of the upper punctum is not necessary if the lower punctum is still intact. A simpler version of the technique may be used if a mass is removed from the medial canthal region without involvement of the medial canthus. Procedure The patient is positioned in sternal recumbency with the head slightly elevated and turned to give good exposure of the surgical field. The lesion to be removed is outlined in the skin of the medial canthus using blue ink (287). This is later excised, creating a large, full-thickness, medial canthal defect. However, prior to mass removal, the surgeon must first cannulate the upper punctum 128 using a large diameter nonabsorbable suture that is then passed through the canaliculus into the nasolacrimal duct until it exits the nose (288). (For details on how this is sutured onto the alar fold see Superficial temporary artery axial pattern flap, p. 139.) The suture is left in place for 3 weeks, when re-epithelialization around the suture will have oc - curred and it can then be removed. The path of the incision is planned so that it creates a flap that takes the shape of the dorsolateral quarter of a rhomboid located medial to the lesion (289). The width of the flap is slightly larger than the width of the defect and its length should at least equal the distance from the dorsalmost aspect of the lesion to just over its mid-point. Once the flap has been created it should be freed from the underlying tissues with gentle dissection so that it can be moved onto the defect (290). The secondary defect created in the bed of the flap is closed by direct apposition of skin (291). Skin sutures are then placed at every angle of the incision line, except in the medial canthal area, which must be reconstructed (292). The medial canthus is closed by placing a ‘holding’ suture (i.e. one that travels through the tarsal plate) with a buried knot, followed by a holding and appositional figure-of-eight suture pattern (293). 286 286 Figure-of-eight suture. This suturing technique may be used on its own or, when indicated, in addition to the tarsal plate suture. It provides perfect alignment of the wound edges and it positions the knot on the skin’s surface, away from the eye. The long piece of the suture may be used to close the skin surface with a single interrupted suture. 285 Tarsal plate suture or buried knot. The purpose of this suturing technique is the crea - tion of a buried knot using a vertical mattress suture pattern. The long end of the suture knot is then used for suturing the subcutaneous skin in a simple continuous pattern. When this technique is used in the eyelid margin, it is referred to as a tarsal plate suture because the suture travels through this structure. Depending on the reconstruction, a figure-of-eight suture is sometimes used on the skin surface in addition to a tarsal plate suture (as shown on the right side of the diagram). Reconstructive techniques of the eyelids a a' b b' a = a' = 1–2mm b = b' = 3–4mm Tarsal plate 285 Tarsal plate suture with buried knot ExternalAll internal 129 290 Incisions are made into the skin following the predrawn outline and the flap is gently dissected from the underlying tissues. 288 The lesion is excised, full- thickness, after passing a large diameter nonabsorbable suture through the upper punc - tum and then through the nasolacrimal duct until it exits via the nasal ostium. 287 The lesion to be removed is marked in blue ink. 291 The donor site is closed by simple apposition of the skin edges. 292 The incision is closed first by placing nonabsorbable sutures at every angle, except for the medial canthus. 289 The flap is carefully planned to create the dorsolateral quarter of a rhomboid medial to the lesion, as shown. 287 288 289 290 291 292 Reconstructive techniques of the eyelids 293 The medial canthus is closed in two layers with non - absorbable sut - ure material. The first suture travels through the tarsal plate. This offers tissue holding power and has a buried knot. 293 This double closure ensures wound integrity and minimizes the risk of wound dehiscence. The surgeon must ensure that the suture does not damage the nasolacrimal duct or canaliculi of the upper or lower eyelid as it travels through the canthal tissue. The figure-of-eight suture pattern (286) is tech - nically demanding because each half of the suture must be an exact mirror image of the other to avoid appositional defects. The needle is first inserted into the lower eyelid skin, approximately 4 mm away from its edge, and it exits at the subcutaneous level into the defect. The needle then crosses over onto the other side ofthe defect, entering the upper eyelid through the subcutaneous tissues, approxi - mately 2 mm from the eyelid margin, and exiting near to or through a meibomian gland opening 1–2 mm away from the edge of the wound. At this point the needle crosses over to the lower eyelid by entering through or next to a meibomian gland, also 1–2 mm away from the edge of the wound. The needle exits through the subcutaneous tissue of the lower eyelid into the wound approximately 2 mm from the eyelid margin. The needle then crosses the wound one last time to enter the upper eyelid subcutaneously approximately 4 mm from the eyelid margin and exiting through the skin of the eyelid. This pattern results in a symmetrical loop of tissue, which rests over the flat section of the edge of the eyelid where the openings of the meibomian gland openings are situated. Two pieces of suture cross over each other in symmetry within the wound and the suture ends, exit either side of the wound through the skin, mirroring each other, and allow the suture knot to be tied on the surface of the skin away from the eye (294). The remainder of the skin is then closed with nonabsorbable suture material ensuring that the suture ends do not reach the ocular surface (295). The cannulated suture that is left in place to reconstruct the upper canaliculus and punctum is removed after approximately 3 weeks once re-epithelialization of these structures around the suture has occurred. References Blanchard GL, Keller WF (1976) The rhomboid flap for the repair of extensive ocular adnexal defects. J Am Anim Hosp Assoc 12:576–580. Hoffmann A, Blocker T, Dubielzig R et al. (2005) Feline periocular nerve sheath tumors: a case series. Vet Ophthalmol 8:153–158. Ng SG, Inkster CF, Leatherbarrow B (2001) The rhomboid flap in medial canthal reconstruction. Br J Ophthalmol 85:556–559. Teske SA (1998) The modified rhomboid transposition flap in periocular reconstruction. Ophthalmic Plast Reconstr 14:360–366. 130 294 The second suture is in a figure- of-eight pattern. This is designed to anchor at the tarsal plate while achieving symmetrical tissue apposition. 295 The remainder of the skin is closed with interrupted sutures making sure that suture ends do not contact the eye. 294 295 Reconstructive techniques of the eyelids Modified cross lid flap Overview This technically demanding two-stage technique was originally described by Mustarde in 1971 for use in humans. It was later modified by Munger and Gourley to repair upper eyelid defects of up to 75% of the length of the eyelid in dogs and cats, allowing for a rotating flap containing the lower eyelid to recreate the upper eyelid while preserving the lat eral and medial canthi. The transposed pedicle is given time to heal within the upper eyelid and then it is transected. This is followed by repair of the defect created in the lower eyelid using an H-plasty. A further modification is described below where the H-plasty is performed during the first stage with the aim of decreasing the overall wound tension between stages one and two. Instead of an H-plasty, the surgeon may also perform a lip-to-eye mucocutaneous subdermal plexus rotating flap. This technique is described later (p. 134) and it has been reported in the veterinary literature for use in dogs and cats. The eye must be kept hydrated, using a viscous tear preparation and antibiotic drops or ointment, during the time between the two surgical stages as eyelid function will be compromised and corneal lesions could develop. Hydration is also likely to help reduce the formation of adhesions between the flap and the H-plasty during this time. Procedure The patient is positioned in sternal recumbency with the head slightly elevated and turned to give good exposure of the surgical field. The lesion to be removed is marked in the skin of the central upper eyelid using blue ink (296). The lesion is then excised, creating a large, full-thickness eyelid defect (297). The dimensions of the flap that will be created from the lower eyelid are carefully planned (298, 299). The pivoting point of the flap will ensure a direct blood supply exists until the transposed eyelid heals into the defect in the upper eyelid, which will act immediately as a source of blood for the most distal aspects of the flap. 131 296 The lesion to be removed is marked in blue ink. 298 The flap outline is planned with its pivot point located medially. 297 The lesion is excised, creating a full-thickness defect. 299 Incisions are made into the skin following the planned outline. 296 297 298 299 Reconstructive techniques of the eyelids The pivot point of the flap must be small enough to allow for rotation, but large enough to allow for the flap to maintain a direct blood supply. The eyelid is transposed with its conjunctival tissue, which also maintains its own blood supply via the pivot point. The lateral aspects of the flap are sutured to the medial aspect of the upper eyelid defect, starting with a deep conjunctival suture of absorbable suture material and a buried knot (the knot ends are facing the tissue and not the eye) (300). Suturing is continued from medial to lateral in a simple continuous suture pattern using the long end of the thread (301). The two eyelid edges are apposed medially. This junction is best apposed using a figure- of-eight suture pattern, (see Rhomboid flap, p. 128) (302). The remainder of the skin wound is closed in a simple interrupted pattern using nonabsorbable suture material (303). The resulting defect of the lower eyelid is then closed with an H-plasty (304, 305). Alternatively, a lip-to-eye mucocutaneous subdermal plexus rotating flap can be used. The latter ensures a cosmetic, trichiasis-free, mucosa-lined eyelid repair, although it is more time consuming and technically more demanding. By 2 weeks, the flap should have healed into the upper eyelid defect and the skin sutures may be removed. If adhesions have formed between the flap and the H-plasty, they must be cut. At this stage the pivot point of the flap can be transected and the medial edge of the lower eyelid transposed to the upper eyelid, where it becomes the lateral edge of the upper eyelid. This requires that part of the lateral section of the transposed flap is broken down and redundant flap tissue is removed to accommodate the new lateral eyelid edge. In addition, the small wound created in the lower medial eyelid, where the pivot of the graft was transected, is incorporated into the H-plasty (306, 307). References Esson D (2001) A modification of the Mustardé technique for the surgical repair of a large feline eyelid coloboma. Vet Ophthalmol 4:159–160. Munger RJ, Gourley IM (1981) Cross lid flap for repair of large upper eyelid defects. J Am Vet Med Assoc 178:45–48. Mustardé JC (1971) Surgical treatment of malignant tumors of the upper lid. Chir Plastica 1:25–33. 132 300 The lateral conjunctiva of the transposed eyelid is sutured to the medial conjunctiva of the upper eyelid defect. 301 The long end of the knot is used to suture the rest of the conjunctival tissue in a simple continuous pattern. 300 301 Reconstructive techniques of the eyelids 133 302 The medial edge of the upper eyelid is sutured to the transposed eyelid edge of the graft in a figure-of-eight pattern using absorbable suture material. 303 The skin is sutured with simple interrupted, absorbable sutures. 306 The pivot point of the transposed flap is clipped and the flap is adapted before it is resutured. This results in a small defect in the medial aspect of the H-plasty, which is also sutured. 307 The end result is a cosmetic and anatomically correct upper eyelid with a conjunctival lining and a recreated lower eyelid. 304 The defect created in the lower eyelid is closed using an H-plasty (shown). A lip-to-eye subdermal plexus rotating flap may also be used for this purpose. 305 The finished H-plasty is shown. The transposed flap is allowed to heal for 2 weeks. 302 303 304 305 306 307 Reconstructivetechniques of the eyelids Lip-to-eye mucocutaneous subdermal plexus rotating flap Overview This one-step technique is used to reconstruct lesions of the lower eyelid in dogs by creating a rotating mucocutaneous subdermal plexus flap that contains the edge of the upper lip and its underlying mucosa. In cats it has been used in combination with the Mustardé technique for repair of upper eyelid agenesis, and a modification of this technique has also been used in cats to reconstruct the upper and lower lateral eyelid and lateral canthus using the lateral upper and lower lip and commissure. The use of lip tissue provides a soft, continuous, trichiasis-free eyelid margin as well as a mucosal surface for the recreated eyelid. 134 Procedure The patient is positioned in sternal or lateral recumbency with the head slightly elevated and turned to give good exposure of the surgical field. This includes the mucosal surface of the lip section that is to be transposed. The lesion to be removed is marked in the skin of the lower eyelid using blue ink (308). The lesion is then excised, creating a large, full-thickness eyelid defect (309). The shape and size of the full-thickness lip flap is planned by creating two slightly converging incision lines at a 45° angle to an imaginary line that bisects the medial and lateral canthi (310). The position of the caudal incision of the graft is such that it points to the base of the ear. The distance between the rostral and caudal incisions is slightly larger at the base of 309 The lesion is excised, creating a full-thickness eyelid defect. 308 The lesion to be removed is marked in blue ink. 308 309 Reconstructive techniques of the eyelids the graft than at the edge of the lip, and the width of the graft at the lip is 1–2 mm larger than the width of the defect to be closed. The flap margins are then incised. A full-thickness incision must be made only at the edge of the lip and through 2–3 cm of skin containing buccal mucosa; the rest of the incision is made only through skin and not into the buccal cavity (311, 312). The mucosal side of the flap must then be incised to separate it from the rest of the mucosal surface within the oral cavity (313) 135 313 The mucosal side of the flap is incised parallel to the edge of the lip. 312 The flap is elevated to expose the mucosal side. 310 Two skin incisions, which converge slightly towards the lip, are created. 311 Full-thickness incisions are made at the edge of the lip only and through the skin into the buccal cavity for 2–3 cm. The remainder of the incision path is through skin only. 310 311 312 313 Reconstructive techniques of the eyelids 315 A bridging incision is planned that spans the distance between the most rostral aspect of the base of the flap and the centre of the defect in the lower eyelid. 314 The flap is gently undermined taking care not to damage the subdermal plexus. This will create a pedicle that contains a 2–3 cm mucosal surface at the tip. The graft is then gently undermined to its base while taking great care to preserve the subdermal plexus (314). A flap- bridging incision is then performed from the rostral base of the pedicle to the centre of the lower eyelid defect (315, 316). The flap is sutured into the defect in two separate layers. The first layer uses absorbable suture material to join the conjunctiva at each of the two edges of the eyelid wound to the corresponding mucosa either side of the tip of the pedicle. Suture knots should remain buried within the tissue so that they do not protrude into the newly created conjunctival sac, where they could easily damage the ocular surface (317–319). The lip is sutured in two layers, with care being taken to ensure that the knots of the absorbable sutures placed internally do not protrude into the buccal cavity (320), and the skin is sutured in a simple interrupted pattern using nonabsorbable suture material (321). 136 314 315 Reconstructive techniques of the eyelids 316 The bridging incision is made. 137 317 The conjunctiva is sutured to the transposed mucosa of the pedicle. 318 Simple interrupted sutures with buried knots using absorbable suture material are placed. 319 The lateral side is sutured, followed by the medial side. 320 The lip is sutured in two layers. 321 The skin is closed with simple interrupted sutures using nonabsorbable suture material. 316 317 318 319 320 321 Reconstructive techniques of the eyelids The area close to the eye is sutured in a figure-of- eight pattern (see Rhomboid flap, p. 128) using absorbable suture material and the rest of the skin is closed in a simple interrupted pattern using the same material (322–325). References Esson D (2001) A modification of the Mustardé technique for the surgical repair of a large feline eyelid coloboma. Vet Ophthalmol 4:159–160. Pavletic MM, Lawrence AN, Confer AW (1982) Mucocutaneous subdermal plexus flap from the lip for lower eyelid restoration in the dog. J Am Vet Med Assoc 180:921–926. Whittaker CJ, Wilkie DA, Simpson DJ et al. (2010) Lip commissure to eyelid transposition for repair of feline eyelid agenesis. Vet Ophthalmol 13:173–178. 138 322 The edge of the wound is closed in a figure-of-eight pattern using absorb able suture material. Closure may also include a previously placed internal stitch with a buried knot. 323 The skin in the vicinity of the figure-of- eight is closed in a simple contin - uous pattern using absorb - able suture material that is obtained from the long end of the figure-of- eight suture knot. 324 The closure is cosmetic and should ensure that no knots are too long and in contact with the eye. 325 A smooth eyelid edge with a mucosal side is finally created. 322 323 324 325 Reconstructive techniques of the eyelids Superficial temporal artery axial pattern flap for reconstruction of the upper eyelid Overview This technically demanding surgery has been described for the reconstruction of the medial canthus and part of the upper eyelid of a dog with a mast cell tumour that required wide excision margins, which included the upper punctum. The technique was developed as an alternative to enucleation, which would have been necessary to avoid secondary surface ocular problems due to overexposure. Caudal auricular axial pattern flaps and an axial pattern flap based on a cutaneous branch of the facial artery (see Chapter 5) have also been described in the veterinary literature, where facial skin reconstruction is required following orbital exenteration (removal of the eye, the adnexa and the orbital contents) to treat eyelid tumours. Procedure The patient is positioned in sternal recumbency with the head slightly elevated and turned to give good exposure of the surgical field. The lesion to be removed is highlighted in the skin of the medial upper eyelid and canthus using blue ink (326). The lesion is then excised, creating a large, full-thickness eyelid and canthal defect that can be reconstructed using a superficial temporal artery axial pattern flap. Prior to removal of the mass, the upper punctum is cannulated with a large diameter nonabsorbable suture. This is passed through the canaliculus and nasolacrimal duct until it exits through the nasal ostium in the distal nasal cavity (327). As the suture exits the nose it is sutured to the skin close to the alar fold. The suture is left in place for 2 weeks until a new punctum is formed via re-epithelialization. The lesion is then excised, creating a large full-thickness eyelid and canthal defect that can be reconstructed using a superficial temporal artery axial patten flap. Careful dissection around the nasolacrimal duct is performed using a blade with a sharp end (e.g. No. 11 Parker blade) (328). 139 327 The upper punctum has been cannulated with a large diameter absorbable suture that travels through the nasolacrimal duct and exits through the ostium located in the distal nasal passage. 326 A lesion in the medial canthus, as well as the dissection marginaround it and the proposed graft pedicle, are shown. 326 327 Reconstructive techniques of the eyelids 328 Careful dissection is undertaken around the cannulated nasolacrimal duct to avoid damaging the duct. 328 The full-thickness resection of eyelid includes its conjunctival lining. The conjunctiva that covers the palpebral part of the exposed third eyelid is also removed with the exception of a horizontal strip of conjunctiva that is left intact along the third eyelid margin (329). The rest of the third eyelid is left intact. Once the mass is removed with the required tissue margins, a large defect results (330). This must be closed to avoid desiccation of the ocular surface. A superficial temporal artery axial flap is planned to cover the defect. The graft in the surgery described here originates from the right side of the head, as it is to be rotated into a defect in the left side. The 140 331 The predrawn outline of the pedicle is incised with a scalpel blade. 332 The graft is carefully undermined. 329 The eyelid resection includes the conjunctival lining and a strip of conjunctiva is all that is left along the edge of the third eyelid. 330 The size of the defect created is shown. Exposure of the ocular surface results. 329 331 330 332 Reconstructive techniques of the eyelids predrawn outline of the pedicle is incised and the graft undermined with gentle dissection (331, 332). The graft should cover the defect with no tension prior to suturing (333). The cut edge of the horizontal strip of conjunctiva on the palpebral side of the third eyelid is sutured onto the edge of the graft medially (334). This ensures that the graft contains a soft mucosal side with which to contact the globe. As the pedicle is sutured onto the underlying tissues in its new position, a Penrose drain is placed under it to help collect the fluid that is likely to build-up in the postoperative period (335). The drain exits the skin from a location ventral to the surgical field and it is removed on day 3 or 4 post surgery. 141 333 The graft is laid onto the defect without any tension prior to suturing. 334 The third eyelid is sutured onto the graft medially. 335 A Penrose drain is placed under the graft. 333 334 335 Reconstructive techniques of the eyelids The skin over the head is advanced to bring it closer to the pedicle. The subcutaneous tissue layer is sutured in a simple interrupted pattern with absorbable suture material (336) and the skin is closed in a simple interrupted pattern with nonabsorbable suture material (337). The suture that passes through the nasolacrimal duct is sutured onto the skin next to the alar fold (338). The other end of the suture is secured to the skin in a position that allows a new punctum to form via re- epithelialization in the space between the third eyelid and the graft (339, 340). References Jacobi S, Stanley BJ, Petersen-Jones S et al. (2008) Use of an axial pattern flap and nictitans to reconstruct medial eyelids and canthus in a dog. Vet Ophthalmol 11:395–400 Milgram J, Weiser M, Kelmer E et al. (2011) Axial pattern flap based on a cutaneous branch of the facial artery in cats. Vet Surg 40:347–351. Stiles J, Townsend W, Willis M et al. (2003) Use of a caudal auricular axial pattern flap in three cats and one dog following orbital exenteration. Vet Ophthalmol 6:121–126. 142 337 The skin is closed with simple interrupted sutures. 337 Reconstructive techniques of the eyelids 336 The subcutaneous layer of the graft is sutured to the underlying tissues and the subcutaneous layer of the skin around it. 336 143 339 The other end of the suture lies between the third eyelid and the graft and it is sutured to the external skin. 338 The suture that has passed through the nasolacrimal duct and exited via the nasal ostium is sutured onto the skin near the alar fold. The exit point of the Penrose drain is also seen in this image. 340 The graft, Penrose drain and nasolacrimal duct suture as viewed from above. 338 339 340 Reconstructive techniques of the eyelids Entropion repair and the arrowhead method for correction of lateral canthal entropion involving the upper and lower eyelid Overview All entropion correction techniques are based on the Celsus–Hotz method, a skin–orbicularis oculi muscle excision that is performed only 2 mm away from the eyelid margin with the aim of everting the entropion and redirecting the skin and its hairs away from the ocular surface. The first incision follows the eyelid margin and extends 1–2 mm away from the area that requires correction. The second incision starts and ends at the same point, but curves away from the initial incision during its course. The maximum distance between the two incisions will be determined by the amount of eversion that is required to correct the entropion. This may be done by one of several methods (e.g. by pinching the skin until the desired everting effect is achieved, which is commonly referred to as the 'pinch method'). It is important that the calculation is performed in the conscious patient, prior to anaesthesia and after the instillation of a topical anaesthetic, so as to minimize the effect of eyelid spasm due to corneal irritation. The Celsus–Hotz technique has been modified to suit different parts of the eyelid margin. This is the case with the arrowhead method, which is used to repair the lateral canthal entropion typically seen in asso - ciation with lateral upper and lower eyelid entropion in Shar-Peis and other broad-headed breeds. Procedure The patient is positioned in sternal recumbency with the head slightly elevated and turned to give good exposure of the surgical field. In the case described here there is lateral canthal entropion with extension into the lateral upper and lower eyelids (341). The incision paths are outlined (342). The innermost path is situated 2 mm away from the eyelid margin and starts 1 mm medial to the most central section of the entropic upper and lower eyelids. It continues along the eyelid margins until the two incision paths meet near the lateral canthus. The outermost path of the incision courses from the same starting point as the innermost path and ends 4–6 mm lateral to the lateral canthus. The outer path curves away from the inner path and the width of the curve is pre - determined by the pinch method, which shows the degree of correction required to evert the eyelid margin. The skin and orbicularis oculi muscle are incised as planned and the skin–orbicularis oculi section located between the incisions is removed (343, 344). The resulting surgical wound is sutured in a single layer of simple interrupted sutures. The first suture is placed at the lateral canthus (345). A layer of sutures is then placed at the medial end of the incision path of the upper and lower eyelids. This is followed by a second layer of sutures placed 1–2 mm away from the lateral canthal suture (346). At this point, another layer of sutures is placed between the first two, bisecting the surgical wound. The principle of bisection is followed until the entire surgical wound is closed with single interrupted sutures spaced 1–2 mm apart (347, 348). Reference Stades F, Gelatt K (2007) Eyelid surgery. In: Veterinary Ophthalmology, 4th edn. (ed K Gelatt) Blackwell Publishing, Ames, pp. 563–617. 144 Reconstructive techniques of the eyelids 145 343 The skin incision is shown as it wraps around the lateral eyelid margin of the right eye of this dog. 344 The island of skin and the orbicularis oculi muscle are excised. 347 Further sutures are placed between the first two layers of sutures, bisecting the surgical wound. 348 The skin suturing of the arrowhead entropion repair is shown near completion. 345 Suturing of the wound starts with a simple interrupted suture in the lateral canthus. 346 Sutures are placed at the lateral and medial ends of the incision paths of the upper and lower eyelid. 343 344 345 346 347 348 Reconstructive techniques of theeyelids 341 A lateral canthal entropion, which extends into the upper and lower lateral eyelids of the right eye, is shown. 342 The incision paths for the arrowhead entropion correction of the lateral canthus and lateral upper and lower eyelid are shown. 341 342 Stades technique for correction of upper eyelid entropion/trichiasis Overview This technique was originally described by Frans Stades in 1987 to treat upper eyelid entropion/ trichiasis in dogs with a large amount of facial skin and heavy ears. These dogs are predisposed to progressive drooping of the facial skin and upper eyelid, which loses contact with the eye and becomes entropic. This procedure describes the removal of the row of upper cilia and adjacent skin hairs from the upper eyelid edge, everting it in the process and avoiding further hairs from growing along its edge. This problem typically affects Cocker Spaniels, Clumber Spaniels, Bloodhounds and other dogs with similar facial characteristics. The technique addresses neither the progressive droop of the skin, which will continue over the life of the animal, nor the lower eyelid, which may also have central ectropion with lateral entropion. In addition, it does not shorten the palpebral length, which often exceeds the average of 33 mm found in most medium and large breed dogs by 7 mm or more. Additional techniques and modifications are required to solve these problems. In cases of macropalpebral fissure, this author has previously modified the Stades procedure successfully by adding a central wedge resection that shortens the length of the upper eyelid. Other techniques range from shortening the lower eyelid via a skin wedge resection to the recently reviewed V-to-Y procedure, which is specifically designed to correct lower eyelid ectropion, medial and lateral canthoplasties and reduce the interpalpebral fissure length in one step, and rhitidectomy procedures, which reduce the amount of excess (face-lift) skin on the head. Procedure The patient is positioned in sternal or lateral recumbency with the head slightly elevated and turned to give good exposure of the surgical field. The surgical landmarks are marked with blue ink (349). A large section of skin is removed from the upper eyelid. The dorsalmost aspect of the incision path is determined by carefully positioning the blunt end of an instrument inside the dorsal conjunctival fornix. Externally, and just above it, the upper eyelid usually creates a fold. The lateralmost part of the skin excision ends approximately 2 mm lateral to the lateral canthus and extends medially just beyond the point where upper eyelid cilia do not grow in the dog; this is approximately the medial fourth of the upper eyelid. The first incision is made along the upper eyelid by inserting a pointed blade, such as a No. 11 Bard-Parker, parallel to the eyelid margin and only 1 mm away from it (350, 351). The eyelid must be kept under tension by stretching it manually or with an instrument. The meibomian glands should not be damaged in the process if possible, while the blade 146 349 The surgical landmarks for the skin excision of the Stades procedure are shown, including the position of the upper conjunctival fornix. 350 A pointed scalpel blade is introduced perpendicular to the tensed eyelid margin. 349 350 Reconstructive techniques of the eyelids must be deep enough to excise the hair follicles that give rise to the upper eyelid cilia and the skin hairs adjacent to them. This may be difficult as hair follicles often lie in very close proximity to the meibomian glands. If any hair follicles are identified in an area 4 mm wide above the eyelid margin, they should be destroyed with a gentle scrape using the scalpel blade (352). A second incision is then made perpendicular to the eyelid skin and starting and ending at the same point. The course of the second incision curves dorsally until it reaches the dorsalmost surgical landmark as described above (353). The island of skin inside the incision path is undermined and excised (354). The dorsal edge of the skin wound may be undermined so as to free it for approximately 5 mm. This allows the edge to be moved and sutured to an area approximately 4 mm above the eyelid margin, immediately along the 147 353 The line of the second incision is shown as it curves dorsally. 354 The skin above the upper eyelid is undermined and excised. 352 Residual hair follicles in the wound area above the eyelid margin are destroyed with gentle scraping. 352 353 354 351 The incision extends from 2 mm lateral to the lateral canthus to the medial fourth of the upper eyelid. 351 Reconstructive techniques of the eyelids dorsal edge of the tarsal plate, which contains the meibomian glands, and without causing exces sive eyelid eversion (355). Simple interrupted sutures are placed 1–2 mm apart to secure the skin edge to its new location. Alternatively, they may be spaced approximately 3–4 mm apart, followed by a simple continuous suture pattern. The resulting strip of hairless tissue between the eyelid edge and the skin edge is allowed to heal by granulation tissue (356). References Donaldson D, Smith KM, Shaw SC et al. (2005) Surgical management of cicatricial ectropion following dermatophaties in two dogs. Vet Ophthalmol 8:361–366. Stades FC (1987) A new method for the correction of upper eyelid entropion-trichiasis: operation method. J Am Anim Hosp Assoc 23:603–606. Stades FC, Boevé MH (1987) Surgical correction of upper eyelid entropion-trichiasis: results and follow up for 65 eyes. J Am Anim Hosp Assoc 23:607–610. Stades FC, Boevé MH, van der Woerdt A (1992) Palpebral fissure length in the dog and cat. Prog Vet Compar Ophthalmol 2:155–161. 148 355 The dorsal skin wound is undermined by 5 mm or less to assist in moving the skin edge to a location 4 mm dorsal to the eyelid edge. 355 356 The result after suturing is a strip of hairless tissue that heals by granulation tissue. 356 Reconstructive techniques of the eyelids Munger–Carter flap adaptation of the Kuhnt–Szymanowski/Fox–Smith procedure for correction of lower eyelid ectropion and macroblepharon in dogs Overview The technique was originally developed for use in humans by Kuhnt–Szymanowski and was later modified by Blaskovic, who avoided splitting the eyelid edge and damaging the meibomian glands. It underwent further adaptations by Fox and Smith and was described for use in dogs by Munger and Carter in 1984 to correct what the authors described as atonic entropion. The technique shortens the lower eyelid by incorporating a wedge resection under a skin flap. It results in correction of central lower eyelid ectropion and the accompanying medial and lateral entropion and it lifts the lateral canthus. It may be complemented by an upper eyelid wedge resection for reduction of the upper eyelid length and in selected cases by the Stades procedure, which may be further modified by incorporating a wedge resection in its centre. Procedure The patient is positioned in sternal recumbency with the head slightly elevated and turned to give good exposure of the surgical field. The incision path courses along, and 2 mm away, from the lower eyelid margin. It extends from an area 2 mm medial to the central eyelid ectropion and extends 10 mm lateral and 4 mm dorsal to the lateral canthus to descend from that point (357). This creates a triangular flap of skin, which is carefully undermined and reflected downwards (358). 149 357 The incision path is shown coursing along the lower eyelid margin and extending from the central eyelid to an area dorsolateral to the lateral canthus before descending. 358 The triangular flap of skin is shown reflected downwards and exposing the eyelid edge and eyelid stroma in preparation for the next step. 357 358 Reconstructive techniques of the eyelids A full-thickness wedge of lower eyelid edge and eyelid stroma, muscle and conjunctiva, equal to the amount of eyelid shortening that is desired, is excised (359,360). This is closed with a figure-of-eight suture pattern (see Rhomboid flap) (361, 362). The long end of the suture is used to close the wedge resection at the level of the eyelid stroma (which also approximates the wound edges at the level of the conjunctiva) using a simple continuous suture pattern (363, 364). The flap of skin becomes oversized by an amount equal to the amount of skin removed in the wedge resection. The flap is then equally shortened before being sutured back onto the skin (365, 366). The first simple interrupted skin suture is placed in the apex of the triangle situated lateral to and slightly above the lateral canthus. To complete the closure the rest of the sutures are placed along the edge of the wound approximately 1 mm apart (367). References Munger RJ, Carter JD (1984) A further modification of the Kuhnt–Szymanowski procedure for correction of atonic entropion in dogs. J Am Anim Hosp Assoc 20:651–656. Stades F, Gelatt K (2007) Eyelid surgery. In: Veterinary Ophthalmology, 4th edn. (ed K Gelatt) Blackwell Publishing, Ames, pp. 563–617. 359, 360 A full-thickness wedge is excised from the eyelid margin in order to reduce the length of the lower eyelid by the desired amount. 359 360 362 361, 362 A figure-of-eight suture pattern is used to close the defect created by the wedge resection. 361 Reconstructive techniques of the eyelids150 Reconstructive techniques of the eyelids 151 363, 364 The long end of the suture is used to complete the closure of the wedge resection with a simple continuous suture pattern. 363 364 365, 366 The oversized flap of skin is reduced in size by an amount equal to the amount of skin removed in the wedge resection. 365 366 367 Sutures are placed along the edge of the wound approximately 1 mm apart and starting at the apex of the triangle lateral to the lateral canthus. 367 This page intentionally left blank Chapter 7 Reconstructive techniques of the neck and trunk 153 Marijn van Delden, Sjef C. Buiks and Gert ter Haar • Omocervical axial pattern flap • Thoracodorsal axial pattern flap • Cranial superficial epigastric axial pattern flap • Cutaneous trunci myocutaneous flap • Latissimus dorsi myocutaneous flap • External abdominal oblique muscle flap • Tensor fascia lata flap • Episioplasty • Scrotal flap • Tail flap/lateral caudal axial pattern flap Omocervical axial pattern flap Overview An omocervical axial pattern flap can be used for closing large skin defects of the face, neck, head, ear, shoulder and axilla. This axial pattern flap is based on the superficial cervical branch of the omocervical artery and vein. Both the artery and vein enter the skin cranial to the shoulder at the level of the prescapular lymph node and the cranial shoulder depression, and run dorsally just cranial to the scapula. The boundaries of the flap are the acromion of the scapula ventrally, the spine of the scapula caudally and a line parallel to the caudal border cranially. The caudal border should be approximately twice the distance from the spine of the scapula to the prescapular lymph node. The distal border of the flap is the dorsal midline; however, it may extend over to the contralateral shoulder region. The omocervical axial pattern flap is a versatile flap that can be rotated in numerous directions (368, 369). Procedure The animal is positioned in lateral recumbency with the forelimb in a relaxed position, perpendicular to the trunk. A line is drawn over the spine of the scapula; this will be the caudal border of the flap. The outline of the cranial incision is parallel to the caudal border and equals the distance from the prescapular lymph node to the caudal incision outline (370). The flap can be extended if necessary to the dorsal midline and to the contralateral scapulohumeral joint. The opposite omocervical direct cutaneous artery and vein must be ligated and divided. The flap is undermined below the level of the sphincter colli superficialis muscle, starting at the distal part of the flap. Stay sutures are placed in order to rotate the flap from the donor site into the skin defect in the neck and to ensure no tension will be present on the flap after suturing (371). It is important to ensure that the vessels are not damaged or occluded while undermining and rotating the flap (372). A bridging incision is made in the skin between the flap and the defect (373). The flap is rotated into the defect and the subcutaneous tissues are sutured (over a Penrose drain, if needed) in an interrupted pattern using absorbable monofilament suture material (374). The skin is apposed with interrupted sutures using 4-0 nonabsorbable suture material or staples (375). Reconstructive techniques of the neck and trunk154 368, 369 Schematic representation of the omocervical axial pattern flap. The coloured part of the dog depicts the estimated area that can be reached by the flap. 368 369 Reconstructive techniques of the neck and trunk 155 370 A large defect is created in the neck. The head is on the right side of the photograph. The ventral side of the dog is at the bottom of the picture. The outline of the omocervical axial pattern flap is drawn on the skin. 371 After undermining the flap, it is rotated into position. 372 The base of the flap, with the superficial cervical branch of the omocervical artery, is shown. 374 The flap is rotated into the recipient site and the subcutaneous tissues are sutured in place. A Penrose drain is placed. 373 Before suturing the flap into position, a bridging incision is made between the flap and the defect. 375 The end result of an omocervical axial pattern flap procedure is shown. The skin has been closed using staples. 370 371 372 373 374 375 An example of an omocervical axial pattern flap for closure of a large defect as the result of tumour excision around the ear base of a cat is shown (376–379). References Degner DA (2007) Facial reconstructive surgery. Clin Tech Small Anim Pract 22:82–88. Hedlund CS (2007) Surgery of the integumentary system. In: Small Animal Surgery, 3rd edn. (eds TW Fossum, CS Hedlund, AL Johnson et al.) Mosby Elsevier, St. Louis, p. 212. Pavletic MM (2010) Atlas of Small Animal Wound Management and Reconstructive Surgery, 3rd edn. Wiley–Blackwell, Ames, pp. 374–375. Pope ER (2006) Head and facial wounds in dogs and cats. Vet Clin North Am Small Anim Pract 36:793–817. Thoracodorsal axial pattern flap Overview Thoracodorsal axial pattern flaps can be used to cover defects involving the shoulder, forelimb, elbow, axilla and thorax. This flap is based on the cutaneous branch of the thoracodorsal artery and associated vein. The moderately sized thoracodorsal cutaneous artery branches in a dorsal direction behind the scapula. If a long flap is required, it may be necessary to divide the opposite cutaneous branch of the thoracodorsal artery and vein. The cranial boundary of the flap is the spine of the scapula. The caudal boundary is the skin parallel to the cranial incision, equal to the distance from the cranial incision to the caudal shoulder depression. The incisions are extended dorsally as far as the dorsal midline, but they can be extended to the contralateral side. Alternatively, a Reconstructive techniques of the neck and trunk156 376 377 376 A cat with a large mass caudoventral to the right ear canal is shown. An omocervical axial pattern flap is outlined. 377 The mass has been resected and the flap harvested. 378 379 378 The flap has been sutured in place. The result immediately after surgery is shown. 379 Ten days after surgery and suture removal. 383 The outline of the thoracodorsal axial pattern flap, the course of the vasculature and the defect are drawn on the skin. The head is on the left side of the photograph. The ventral side of the dog is at the bottom of the picture. 384 The defect has been created and the skin incisions for the thoracodorsal axial pattern flap have been made. 157Reconstructive techniques of the neckand trunk 380–382 Schematic representation of the thoracodorsal axial pattern flap. The coloured part of the dog depicts the estimated area that can be reached by the flap. 380 383 384 381 382 standard peninsular or hockey-stick shaped configuration can be created, depending on the location and size of the defect (380–382). Procedure The animal is positioned in lateral recumbency with the forelimb in a relaxed position, perpendicular to the trunk. A line is drawn over the spine of the scapula; this will be the cranial border of the flap. The line of the caudal incision is parallel to the cranial border and equals the distance from the cranial border to the caudal shoulder depression (383). The flap can be extended if necessary to the dorsal midline and to the contralateral site or in a hockey-stick shaped configuration. The skin is incised along the borders of the flap (384). The flap is undermined below the level of the cutaneous trunci muscle, starting at the distal part of the flap. While undermining and rotating the flap, it is important to make sure that the vessels are not damaged or occluded (385, 386). A bridging incision is made in the skin between the flap and the defect (387). The flap is rotated into the defect and the subcutaneous tissues of the flap are sutured to the subcutaneous tissue of the recipient site (over a Penrose drain, if needed) in an interrupted pattern using absorbable monofilament suture material (388). The subcutaneous tissues of the donor site are closed using absorbable monofilament suture material (389). The skin is apposed with interrupted sutures using 4-0 nonabsorbable suture material or staples (390). An example of a thoracodorsal axial pattern flap for closure of a large thoracic wall defect in a dog is shown (391–394). References Degner DA (2007) Facial reconstructive surgery. Clin Tech Small Anim Pract 22:82–88. Hedlund CS (2007) Surgery of the integumentary system. In: Small Animal Surgery, 3rd edn. (eds TW Fossum, CS Hedlund, AL Johnson et al.) Mosby Elsevier, St. Louis, pp. 212–213. Pavletic MM (2010) Atlas of Small Animal Wound Management and Reconstructive Surgery, 3rd edn. Wiley–Blackwell, Ames, pp. 376–377. Pope ER (2006) Head and facial wounds in dogs and cats. Vet Clin North Am Small Anim Pract 36:793–817. Reconstructive techniques of the neck and trunk158 387 Before suturing the flap into position, a bridging incision is made between the flap and the defect. 388 The flap is rotated into the recipient site and the subcutaneous tissues of the flap are sutured in place. A Penrose drain has been placed. 387 388 385 The flap is undermined beneath the cutaneous trunci muscle. 386 The flap is undermined to the level of its base near the origin of the thoracodorsal artery and vein. 385 386 Reconstructive techniques of the neck and trunk 159 389 The subcutaneous tissues of the donor site are apposed using absorbable monofilament suture material. 390 The end result of a thoracodorsal axial pattern flap procedure is shown. The skin has been sutured in an interrupted pattern using nonabsorbable suture material. 389 390 391 392 391 Dog in left lateral recumbency with a large defect of the skin and subcutis in the lateral thoracic region. The head is on the right side of the photograph. 392 After approximation of the muscles, a large thoracodorsal axial pattern flap with hockey-stick configuration has been raised and rotated into position. 393 394 393 The flap has been sutured into position and the subcutaneous tissues and skin have been approximated. Penrose drains are placed. 394 Three days after surgery, the Penrose drains are removed. Reconstructive techniques of the neck and trunk160 incision. The flap can be either peninsular or island in design (395, 396). Procedure The animal is placed in dorsal recumbency with the forelimbs extended cranially. The flap is outlined with the base of the flap located just lateral to the xyphoid process. The medial incision is outlined in the ventral midline and the lateral incision is placed at a distance equal to the distance from the nipples to the midline. The caudal limit is preferably the fourth mammary gland (397). The skin is then incised according to the predrawn outline (398). The flap is undermined using scissors, starting from the midline and extending to the lateral aspect of the flap, beneath the panniculus and supramammarius muscles. The cranial epigastric artery and vein should be preserved during flap dissection and harvesting (399, 400). Stay sutures are inserted into the caudal border of the flap to enable nontraumatic rotation of the flap into the defect. The vessels must not be kinked or occluded when rotating the flap (401). The flap is sutured into the recipient site by placing a few subcutaneous interrupted sutures of monofilament absorbable suture material. Cranial superficial epigastric axial pattern flap Overview A cranial superficial epigastric axial pattern flap can be used to close large sternal skin wounds after tumour resection or injury. The flap is based on the cranial superficial epigastric artery. Although there are some anatomical variations, the artery and vein are most commonly located in the hypogastric area, caudal to the ventral border of the costal arch and medial to the xyphoid process. Because the vessels are shorter, this flap is smaller and less versatile than the caudal superficial epigastric axial pattern flap. Depending on the size of the patient, the base of the flap is located in the region of the cranial epigastric vessel, entering the skin lateral to the abdominal midline and a few centimetres caudal to the cartilaginous border of the ventral thorax. The flap may include mammary glands two, three, four and, possibly, five. In males, the end of the flap must be cranial to the prepuce to enable closure of the donor site and minimize the risk of necrosis of the flap. The midline of the abdomen serves as the central border of the flap, whereas the distance from the midline to the mammary nipples serves as the reference for measurement for the lateral 395, 396 Schematic representation of the cranial superficial epigastric axial pattern flap. The coloured part of the dog depicts the estimated area that can be reached by the flap. 395 396 Reconstructive techniques of the neck and trunk 161 397 A large sternal defect has been created and the superficial cranial epigastric axial pattern flap has been outlined. The head of the dog is located to the right side of the photograph. 398 Skin incisions have been made following the predrawn outline of the flap. 397 398 399 Stay sutures have been placed after the flap has been undermined beneath the panniculus and supramammarius muscles. 400 Care has been taken to ensure that the vessels have not been damaged during the undermining and that they were not kinked or occluded when the flap was rotated. 399 400 401 The flap is rotated into the defect with the help of stay sutures. 401 Reconstructive techniques of the neck and trunk162 The subcutis of the donor site can be closed in an interrupted pattern using absorbable monofilament suture material. When necessary, walking sutures can be used to move the skin over the donor site defect (402). All the subcutaneous tissues are apposed in an interrupted pattern using monofilament absorbable suture material (403). The skin of the donor and recipient sites is closed using nonabsorbable monofilament suture material or staples (404). References Hedlund CS (2006) Large trunk wounds. Vet Clin North Am Small Anim Pract 36:847–872. Hedlund CS (2007) Surgery of the integumentary system. In: Small Animal Surgery, 3rd edn. (eds TW Fossum, CS Hedlund, AL Johnson et al.) Mosby Elsevier, St. Louis, p. 214. Pavletic MM (2010) Atlas of Small Animal Wound Management and Reconstructive Surgery, 3rd edn. Wiley–Blackwell, Ames, pp.384–385. Cutaneous trunci myocutaneous flap Overview A cutaneous trunci flap is a compound flap consisting of three layers:skin, subcutaneous fat and the cutaneous trunci muscle. It can be used to close defects on the trunk as well as large wounds on the forelimb. The thoracodorsal axial pattern flap and lattisimus dorsi myocutaneous flap are harvested from the same area. The thoracodorsal axial pattern flap and the cutaneous trunci myocutaneous flap are better suited for skin defects, whereas the latissimus dorsi myocutaneous flap is better suited for thoracic wall defects where simultaneous reconstruction of the chest with muscle and skin are required. The landmarks for the cutaneous trunci myocutaneous flap are the ventral border of the acromion, the caudal border of the triceps muscle, the head of the 13th rib and the axillary fold. The dorsal flap border is drawn from a point ventral to the acromion and caudal to the border of the triceps muscle, towards the last rib. The ventral border is parallel to 402 Walking sutures have been placed in the fascia of the body wall and the subdermal fascia to assist in closure of the donor site. 403 The subcutaneous tissues in the donor and recipient sites have been apposed. 404 The skin has been closed using staples. 402 403 404 Reconstructive techniques of the neck and trunk 163 is made, starting at the ventral border of the outlined flap and extending through the cutaneous trunci muscle (409). The rest of the flap is incised through the skin, subcutis and cutaneous trunci muscle and then undermined, starting at the dorsal aspect of the flap deep to the cutaneous trunci muscle and continuing towards the base of the flap. the dorsal border, starting in the axillary skin fold (405–407). Procedure The patient is positioned in lateral recumbency with the forelimb in a relaxed position. The outline of the flap is drawn in the donor area using the landmarks described above (408). A skin incision 405–407 Schematic representation of the cutaneous trunci myocutaneous flap. The coloured part of the dog depicts the estimated area that can be reached by the flap. 405 406 407 408 A defect has been created on the forelimb and the borders of the cutaneous trunci myocutaneous flap have been outlined. 408 409 The ventral border of the flap has been incised. The cutaneous trunci muscle is gently undermined using scissors. 409 Reconstructive techniques of the neck and trunk164 413 A bridging incision has been made between the donor and recipient sites. 413 410 After the flap has been dissected through the skin, the subcutis and the cutaneous trunci muscle, it can be lifted and undermined with the help of stay sutures. 410 411 The flap has been dissected beneath the cutaneous trunci muscle and towards its base. 411 412 The flap is rotated into the defect in order to evaluate its size and the location of the bridging incision. 412 subcutaneous tissues of the flap are sutured to the subcutis of the recipient site using absorbable monofilament suture material. The cutaneous trunci layer and the subcutis of the donor site are closed in two separate layers in either an interrupted or continuous pattern using absorbable monofilament suture material (415, 416). The skin is closed routinely using staples or nonabsorbable monofilament suture material (417). Monofilament suture material stay sutures are placed to enable atraumatic manipulation of the flap (410, 411). The flap is then rotated into the defect on the forelimb to make sure it is the correct size and that it can be sutured in place without tension (412). A bridging incision is performed between the donor and recipient sites and the flap is transposed into the defect (413, 414). A Penrose drain is placed if indicated and the donor and recipient sites are closed. The muscle and Reconstructive techniques of the neck and trunk 165 416 The subcutaneous tissues and muscle of the flap are sutured to the subcutis of the defect. The cutaneous trunci muscle and the subcutaneous tissues of the donor site are closed separately. 417 The skin of both the donor and the recipient site is closed in an interrupted pattern using staples or nonabsorbable monofilament suture material. 415 A Penrose drain has been inserted into the donor site underneath the muscle layer. References Hedlund CS (2006) Large trunk wounds. Vet Clin North Am Small Anim Pract 36:847–872. Pavletic MM (2010) Atlas of Small Animal Wound Management and Reconstructive Surgery, 3rd edn. Wiley–Blackwell, Ames, pp. 492–493. Pavletic MM, Kostolich M, Koblik P et al. (1987) A comparison of the cutaneous trunci myocutaneous flap and latissimus dorsi myocutaneous flap in the dog. Vet Surg 16:283–293. 414 The flap has been transposed into the defect and is ready for suturing. 414 415 416 417 Reconstructive techniques of the neck and trunk166 These branches also penetrate the muscle surface towards the cutaneous trunci muscle and the skin. The most prominent intercostal artery is the branch that emerges from the 5th intercostal space and enters the latissimus dorsi muscle. This artery is responsible for much of the perfusion of the middle part of the muscle. Intercostal arteries also supply segmental branches to the dorsal portion of the latissimus dorsi muscle and overlying cutaneous trunci muscle. The landmarks for the latissimus dorsi myocutaneous flap are the ventral border of the acromion, the caudal border of the triceps muscle, the head of the 13th rib and the axillary skin fold (418–420). Latissimus dorsi myocutaneous flap Overview A latissimus dorsi flap can be used to close large thoracic defects, abdominal wall defects and wounds on the elbow. The thickness of this flap is very useful where there is a lack of granulation tissue in an area (e.g. the elbow region) or when thoracic wall recon - structions are required. The latissimus dorsi muscle originates from the thoracolumbar fascia of the thoracic and lumbar spinous processes and from muscular attachments to the last two or three ribs. The insertion of the latissimus dorsi is on the major teres tuberosity of the humerus. The dorsal and ventral portions of the muscle are supplied by the thoracodorsal artery and by branches from the intercostal arteries emerging from the chest wall. 418–420 Schematic representation of the latissimus dorsi myocutaneous flap. The coloured part of the dog depicts the estimated area that can be reached by the flap. 418 419 420 Reconstructive techniques of the neck and trunk 167 424 Dissection deep to the latissimus dorsi muscle is continued until the thoracodorsal artery is encountered. Procedure The patient is positioned in lateral recumbency with the forelimb in a relaxed position. The outline of the donor flap is drawn according to the landmarks described above (421). A skin incision is made, starting at the ventral border of the outlined flap and extending through the cutaneous trunci muscle (422). The incision is extended to the 421 A defect on the forelimb has been created and the latissimus dorsi myocutaneous flap dimensions have been outlined. 422 The ventral border of the flap has been incised. After incision of the skin and subcutis, the incision has to be deepened through the cutaneous trunci muscle and latissimus dorsi muscle. 423 The latissimus dorsi muscle is undermined using scissors. 421 422 423 424 underlying latissimus dorsi muscle using a scalpel or scissors. The remainder of the flap is incised through the skin, subcutis, cutaneous trunci muscle and latissimus dorsi muscle and then undermined, starting at the dorsal aspect of the flap deep to the latissimus dorsi muscle (423). The flap is further undermined towards its base with the help of stay sutures of monofilament suture material (424). Reconstructive techniques of the neck and trunk168 While undermining the muscle, the branches of the intercostal arteries are isolated, ligated and divided deep to the latissimus dorsi muscle. The thoracodorsal artery is identified and preserved just caudal to the border of the triceps muscle at the caudal shoulder depression(425). The flap is rotated into position taking care not to damage or occlude the thoracodorsal artery. The size of the flap and the location for the bridging incision are then assessed (426). A bridging incision is made between the donor and the recipient site (427). The flap is secured by suturing the latissimus dorsi muscle to the subcutaneous tissues of the defect (over a Penrose drain if required) in an interrupted pattern using absorbable monofilament suture material (428). The donor site is closed in three layers. The latissimus dorsi muscle is sutured first in an interrupted or continuous pattern using absorbable monofilament suture material (over a Penrose drain if required). The subcutaneous tissues are then apposed using absorbable monofilament suture material (429). The skin is closed with nonabsorbable monofilament suture material or staples (430). 425 The thoracodorsal artery is visible where it enters the latissimus dorsi muscle just caudal to the border of the triceps muscle. 426 Stay sutures are used to rotate the flap from the donor site to the recipient site. 427 A bridging incision has been made from the donor site to the recipient site. 428 The flap is sutured into the recipient bed and a Penrose drain is placed. 425 426 427 428 Reconstructive techniques of the neck and trunk 169 References Halfacree ZJ, Baines SJ, Lipscomb VJ et al. (2007) Use of a latissimus dorsi myocutaneous flap for one-stage reconstruction of the thoracic wall after en bloc resection of primary rib chondrosarcoma in five dogs. Vet Surg 36:587–592. Hedlund CS (2006) Large trunk wounds. Vet Clin North Am Small Anim Pract 36:847–872. Monnet E, Rooney MB, Chachques JC (2003) In-vitro evaluation of the distribution of blood flow within a canine bipedicled latissimus dorsi muscle flap. Am J Vet Res 64:1255–1259. Pavletic MM (2010) Atlas of Small Animal Wound Management and Reconstructive Surgery, 3rd edn. Wiley–Blackwell, Ames, pp.494–495. Pavletic MM, Kostolich M, Koblik P et al. (1987) A comparison of the cutaneous trunci myocutaneous flap and latissimus dorsi myocutaneous flap in the dog. Vet Surg 16:283–293. 429 Closure of the donor site. The latissimus dorsi muscle and the subcutis have been closed in separate layers. 430 The skin of the donor and recipient sites has been closed using staples. 429 430 Reconstructive techniques of the neck and trunk170 External abdominal oblique muscle flap Overview An external abdominal oblique muscle flap can be used to close full-thickness wall defects in the abdominal or caudal thoracic wall. Because of its elasticity and pliability, this muscle flap is sufficiently large to cover defects as large as 10 " 10 cm in medium-sized dogs. The oblique abdominal muscle consists of two parts: the costal part, which arises from the fifth to the 13th rib, and the lumbar part, which arises from the 13th rib to the thoracolumbar fascia. The aponeurosis of the muscle inserts on the linea alba and its fibres are directed caudoventrally. The neurovascular pedicle is comprised of branches of the cranial abdominal artery, the cranial hypogastric nerve and a satellite vein. This pedicle must be preserved when a lumbar external abdominal muscle flap is pivoted into the thoracic or abdominal wall defect (431, 432). 431, 432 Schematic representation of the external abdominal oblique muscle flap. The coloured part of the dog depicts the estimated area that can be reached by the flap. 431 432 Reconstructive techniques of the neck and trunk 171 Procedure The patient is positioned in lateral recumbency (right lateral recumbency in this example) with both limbs in a relaxed position. The paracostal skin incision, from the level of the epaxial muscles to the ventral midline, 5.0 cm caudal to the 13th rib, is outlined (433). The skin is incised and then undermined between the incision and the defect (in this case in the caudal thoracic region at the level of the 11th and 12th rib) (434). The fascial edges of the external abdominal oblique muscle are identified and divided ventrally from the linea alba and caudally at the level of the skin incision. The muscle is undermined, preserving the neurovascular pedicle, and the flap is transposed to the adjacent defect (435). In order to rotate the flap into the defect and determine an appropriate place for all the sutures, the two free corners of the flap are sutured first (temporarily) cranially into the defect. The base of the flap is then sutured to the caudal corners of the defect (436). Subsequently, the two cranial sutures are removed and the flap is rotated caudally to expose the inner side of the flap. 433 The dog is positioned in right lateral recumbency. The head of the dog is to the right and the ventral side of the dog is at the top of the photograph. A defect has been created in the caudal thoracic region including partial removal of the 11th and 12th ribs. The liver can be seen in the defect. The paracostal incision line for harvesting the external abdominal oblique muscle flap is outlined. 434 After the skin has been incised, it is undermined, using scissors, from the starting point of the incision to the surgical wound. 435 The part of the muscle designated to close the defect is separated caudally and ventrally from the lumbar part of the muscle and transposed into the defect. 436 The muscle flap is temporarily sutured in place in the defect. 433 434 435 436 Reconstructive techniques of the neck and trunk172 Next, the transversus abdominal muscle is located (437). The inner fascial surface of the external abdominal oblique muscle is sutured to the transversus abdominal muscle. This layer is closed using interrupted mattress sutures or in a continuous pattern. Apposing these two muscle layers is important in preventing postoperative abdominal herniation (438). The flap is pulled cranially again and sutured into position in an interrupted pattern using absorbable monofilament suture material. After closing the abdominal wall defect, the subcutis of the donor and recipient sites are sutured with absorbable monofilament suture material (439). The skin is closed routinely with nonabsorbable monofilament suture material or staples (440). References Hedlund CS (2006) Large trunk wounds. Vet Clin North Am Small Anim Pract 36:847–872. Pavletic MM (2010) Atlas of Small Animal Wound Management and Reconstructive Surgery, 3rd edn. Wiley–Blackwell, Ames. pp. 496–497. 437 The muscle flap is folded caudally to expose the transverse abdominal muscle. 439 The flap is sutured into position and the subcutaneous tissues are partly apposed. 438 The transverse abdominal and external abdominal oblique muscles have been sutured using a continuous suture pattern. 440 The skin has been closed routinely using the technique described in Chapter 3 (p. 51) 437 438 439 440 Reconstructive techniques of the neck and trunk 173 Tensor fascia lata flap Overview A tensor fascia lata flap can be used to close full- thickness wall defects in the abdominal wall or to cover chronic wounds of the pelvic region. Because of its elasticity and versatility, this musculocutaneous flap is an efficient option for repair of abdominal wounds requiring both soft tissue and fascia. The technique has been used successfully in human reconstructive surgery. The tensor fascia lata is part of the gluteus muscle group and its blood supply is derived from the lateral circumflex femoral artery, which is a branch of the femoral artery (441–443). Procedure The dog is placed in lateral recumbency, assuring access to the caudal abdominal area and the entire hindlimb (444). An outline of the flap is drawn. The anatomical landmarks for this flap are the greater trochanter dorsally, the stifle ventrally, the biceps femoris muscle caudally and the sartorius muscle cranially. The caudal border of the flap is located in the groove between the superficial biceps femoris and the deep vastus lateralis muscles. The cranial border is parallel to the caudalborder, located in the groove between the tensor fascia lata and the sartorius muscles (445). 444 The animal is positioned in right lateral recumbency. The head of dog is to the left side of the photograph and the left hindlimb at the top. A defect in the abdominal wall has been created. 441–443 Schematic representation of the tensor fascia lata flap. The coloured part of the dog depicts the estimated area that can be reached by the flap. 445 The dimensions of the tensor fascia lata flap are outlined and the caudal skin incision has been made. The top asterisk depicts the greater trochanter while the bottom one depicts the stifle. 444 445 441 442 443 * * Reconstructive techniques of the neck and trunk174 The incision is extended through the skin, the subcutaneous tissue and the deep fascia. The tensor fascia lata is undermined starting at the distal end of the flap and progressing towards the proximal part of the flap. Stay sutures are placed (446). A bridging incision is made between the donor site and the recipient site (447). In order to rotate and secure the flap into the defect, the two distal corners of the flap are sutured into the defect first (448). The rectus abdominis muscle is located in the dorsocaudal wall of the defect and the flap is sutured to the two dorsocaudal corners of the defect. The two cranial sutures can now be removed and the flap turned caudally to allow for visualization of its inner side (449). The inner side of the fascia lata flap is sutured to the rectus abdominis muscle in an interrupted pattern using absorbable monofilament suture material (450). The flap is sutured into the defect in an interrupted pattern using absorbable monofilament suture material (451). The subcutis of the flap is apposed to the defect in a continuous or interrupted pattern using absorbable monofilament suture material (over a Penrose drain if required). The subcutaneous tissues of the donor side are closed routinely (452). The skin of the donor and recipient sites is closed in an interrupted pattern using nonabsorbable monofilament suture material (453). References Demirseren ME, Gokrem S, Ozdemir OM et al. (2003) Hatchet-shaped tensor fascia lata musculocutaneous flap for the coverage of trochanteric pressure sores: a new modification. Ann Plast Surg 51:419–422. Josvay J, Sashegyi M, Kelemen P et al. (2006) A modified tensor fascia lata musculofasciocutaneous flap for the coverage of trochanteric pressure sores. J Plast Reconstr Aesthet Surg 59:137–141. Paletta CE, Freedman B, Shehadi SI (1989) The VY tensor fasciae latae musculocutaneous flap. Plast Reconstr Surg 83:852–7; discussion 858. 446 The tensor fascia lata flap is being harvested with the help of stay sutures. The vastus lateralis and sartorius muscles are visible. 447 The flap is rotated into the defect in order to determine the location of the bridging incision. 446 447 Reconstructive techniques of the neck and trunk 175 450 The fascia lata muscle at the dorsocaudal border of the defect is sutured to the rectus abdominis muscle with interrupted sutures. 451 The fascia lata flap is sutured into the defect. 452 The subcutaneous tissues of the donor and recipient sites have been apposed over a Penrose drain. 453 The skin of both the recipient and donor sites is closed routinely. 450 451 452 453 449 After removing the cranioventral sutures, the flap is turned caudally to expose the inside. 448 The two cranioventral corners of the flap are sutured in place first in order to determine the location of the sutures for the dorsocaudal corners of the flap. 448 449 Reconstructive techniques of the neck and trunk176 Episioplasty Overview Perivulvular dermatitis, as a result of excessive skin folds around the vulva, can be treated with an episioplasty or a vulvoplasty. This technique can also be used as a preventive measure. If severe pyo - derma is present, it should be treated medically before surgery is performed. Depending on the curvature of the folds, a ventral, dorsal or combined episioplasty can be performed. Procedure The animal is placed in ventral recumbency. The amount of skin that can be resected is assessed by grasping the skin folds. Two crescent-shaped lines, which begin near the ventral vulvar commissure and converge dorsally, encircling the vulva, are drawn. The largest amount of skin will be removed dorsally (454). The two lines are incised and the ellipse of redundant skin removed. Excess subcutaneous tissue is also removed (455). The subcutis is closed using interrupted absorbable monofilament sutures with buried knots. The initial sutures are placed in the 3, 9 and 12 o’clock positions. The result of the resection can then be evaluated. If the folds persist, more skin can be excised along the outer margin of the resection (456). When enough skin has been excised, the subcutis is closed in an interrupted pattern using absorbable monofilament suture material (457). The skin is closed routinely in an interrupted pattern using nonabsorbable monofilament suture material (458, 459). References Hedlund CS (2007) Surgery of the integumentary system. In: Small Animal Surgery, 3rd edn. (eds TW Fossum, CS Hedlund, AL Johnson et al.) Mosby Elsevier, St. Louis, p. 245. Hedlund CS (2007) Surgery of the reproductive and genital systems. In: Small Animal Surgery, 3rd edn. (eds TW Fossum, CS Hedlund, AL Johnson et al.) Mosby Elsevier, St. Louis, pp. 721–723. Reconstructive techniques of the neck and trunk 177 458 The skin has been closed in an interrupted pattern using nonabsorbable monofilament suture material. 459 A bitch with a healed episioplasty is shown. 458 459 454 The patient is positioned in ventral recumbency. The anus is situated dorsally, out of view. After assessing the amount of skin that can be harvested, two converging lines are drawn. 455 The excess perivulvular skin has been excised. 454 455 456 The subcutaneous tissues are apposed using monofilament absorbable suture material. The initial sutures are placed in the 3, 9 and 12 o’clock positions. 457 Closure of the subcutis has been completed. 456 457 Reconstructive techniques of the neck and trunk178 Scrotal flap Overview A scrotal flap is a local subdermal flap that is easy to prepare and can be used to cover large defects in the perineal area or the caudal and medial aspect of the thigh. The scrotal skin is thin and has a greater elasticity than truncal skin. This is because of the dartos layer beneath the scrotal skin, which consists of smooth muscle, collagen and elastic fibres. Perineal branches of the external pudendal and cremaster artery supply the scrotum with blood. A prescrotal castration is performed in intact male dogs prior to reconstruction of the defect. A scrotal flap procedure can be performed in previously castrated dogs, but the remaining scrotal skin is less pliable. Procedure The dog is positioned in dorsal recumbency with the hindlimbs positioned cranially and spread wide (460). A routine prescrotal castration is performed. The prescrotal incision is closed routinely (as performed here) or it is incorporated into the base of the flap (461). The skin is incised at the base of the scrotum craniolaterally, so that the base of the flap is on the opposite side of the defect. The scrotal skin is then dissected by separating the tunica dartos and abdominal fascia, and stay sutures are placed (462). Before closing the defect, the hindlimbs are adducted to minimize the tension on the defect and the skin flap. The limbs are directed slightly cranially and dorsally. The subcutaneous tissue of the scrotal flap is sutured to the subcutis of the defect in an interrupted suture pattern using absorbable monofilament suture material (463). The skin is closed routinely in an interrupted pattern using nonabsorbable monofilament suture material (464). References Hedlund CS (2007) Surgery of the integumentary system. In: Small Animal Surgery, 3rd edn. (eds TW Fossum, CS Hedlund, AL Johnson et al.)Mosby Elsevier, St. Louis, pp. 159–259. Matera JM, Tatarunas AC, Fantoni DT et al. (2004) Use of the scrotum as a transposition flap for closure of surgical wounds in three dogs. Vet Surg 33:99–101. Reconstructive techniques of the neck and trunk 179 464 The skin has been closed routinely. 464 463 The hindlimbs have been partially adducted and the subcutaneous tissue apposed over a Penrose drain. 460 The animal is positioned in dorsal recumbency for prescrotal castration prior to harvesting a scrotal flap. 461 The dog has been castrated and a large defect on the medial right thigh has been created. The craniolateral incision for creation of the scrotal flap is shown. 462 After dissection of the scrotal skin, the flap is advanced into the defect using stay sutures. 460 461 462 463 Reconstructive techniques of the neck and trunk180 Tail flap/lateral caudal axial pattern flap Overview A tail flap (or lateral caudal axial pattern flap) can be used to close large caudodorsal trunk defects and skin wounds in the perineal region and hindlimbs. To use the flap, amputation of the tail is necessary. The skin of the proximal cranial 75% of the flap can be used to reduce the possibility of distal flap necrosis. A dorsal midline incision along the length of the tail is used to cover dorsocaudal defects and a ventral midline skin incision is used to cover defects of the perineum and proximal hindlimb. Tail flaps are based on the lateral caudal arteries, which arise from the caudal gluteal arteries. They are located in the subcutaneous tissue of the tail, lateral and ventral to the transverse processes of the caudal vertebrae in the proximal region. In the distal part of the tail, the vessels travel dorsal to the transverse processes (465–467). Procedure The dog is positioned in ventral recumbency. An outline of the incision line for the flap is made (468). A dorsal median skin incision is made from the tail base to the tip of the tail (469). The subcutaneous tissue around the tail vertebrae is dissected, taking care to preserve the right and left lateral caudal arteries and veins (470). Once the tail is completely freed from surrounding subcutaneous tissues, the tail is amputated at the caudal second or third intervertebral space (471– 473). Approximately 75% of the skin flap is preserved by amputating the distal part of the tail with overlying skin (474, 475). Stay sutures are placed in the tip of the flap. 465–468 Schematic representation of the lateral caudal axial pattern flap. The coloured part of the dog depicts the estimated area that can be reached by the flap. 465 466 467 Reconstructive techniques of the neck and trunk 181 470 The subcutaneous tissues are dissected from the tail vertebrae. 471 The skin of the entire tail has been dissected and the right and left lateral caudal arteries and veins have been preserved. 472 The tail is amputated at the second intervertebral space. 473 Completion of the proximal tail amputation at the level of the second intervertebral space. 469 Dorsal view of the back and tail of a dog with the incision line for the tail flap outlined. A defect has been created on the caudal back of the dog. 470 The dorsal median skin has been incised. 468 469 470 471 472 473 475 The distal part of the tail is removed together with the overlying skin. 475 474 The distal part of the tail is amputated. 474 The flap is then rotated into position in order to determine an accurate flap length (476). A bridging incision is made between the donor site and the recipient site (477). The flap is rotated into the defect and the subcutaneous tissues are apposed in an interrupted pattern using absorbable monofilament suture material (478). The skin is closed with interrupted sutures of nonabsorbable suture material or staples (479). References Hedlund CS (2006) Large trunk wounds. Vet Clin North Am Small Anim Pract 36:847–872. Pavletic MM (2010) Atlas of Small Animal Wound Management and Reconstructive Surgery, 3rd edn. Wiley–Blackwell, Ames. pp. 400–401. Saifzadeh S, Hobbenaghi R, Noorabadi M (2005) Axial pattern flap based on the lateral caudal arteries of the tail in the dog: an experimental study. Vet Surg 34:509–513. 476 The flap is rotated into the defect with the help of stay sutures. The appropriate length of flap and the location of the bridging incision are determined. 477 A bridging incision between the donor and recipient sites has been made. 478 The subcutaneous tissues have been apposed. 479 The skin has been closed routinely. 476 477 478 479 182 Reconstructive techniques of the neck and trunk • Lateral thoracic artery axial pattern flap • Superficial brachial axial pattern flap • Axillary (forelimb) fold flap • Flexor carpi ulnaris muscle flap • Phalangeal fillet (digit I or dewclaw [P-I]) • Phalangeal fillet (digits II–IV) • Fusion podoplasty • Segmental pad transfer Chapter 8 Reconstructive techniques of the forelimb 183 Sjef C. Buiks, Tjitte Reijntjes and Jolle Kirpensteijn Lateral thoracic artery axial pattern flap Overview A lateral thoracic artery axial pattern flap is mainly used for defects involving the elbow region, but it also has potential for other difficult wounds within its arc of rotation. The flap is based on the lateral thoracic artery and vein. The lateral thor - acic artery is the second branch of the axillary artery and is directed caudally and runs deep to the axillary lymph node. The same artery also branches off to the deep pectoral muscle and the latissimus dorsi muscle. The lateral thoracic artery has multiple superficial branches. This network of blood vessels in the subcutaneous tissue supplies the skin dorsal and ventral to the main trunk of the artery and reaches from the midline ventrally to the mid-thorax dorsally. The anatomical position of the lateral thoracic artery is comparable in dogs and cats, but in dogs the artery supplies the skin of the ventral and lateral body wall up to the caudal aspect of the eigth rib, whereas in cats it supplies the skin as caudally as the last rib. The point where the lateral artery becomes superficial is the centre of the flap. This point (caudal to the triceps muscle and adjacent to the dorsal border of the deep pectoral muscle) can be palpated. The landmarks for the flap are the midline ventrally and dorsally a line parallel to the ventral border at a distance that equals the distance from the centre of the flap to the ventral border. The caudal border is the eigth rib in dogs and the 13th rib in cats. A smaller size flap can be created to minimize skin flap necrosis (480, 481). Procedure The patient is placed in lateral recumbency with the forelimb in a relaxed position. In this case a large defect has been created in the elbow region (482). The outline of the lateral thoracic artery flap is 184 480, 481 Schematic representation of the lateral thoracic artery axial pattern flap. The coloured part of the dog depicts the estimated area that can be reached by the flap. Reconstructive techniques of the forelimb 482 A defect has been created on the right forelimb. 482480 481 Reconstructive techniques of the forelimb 185 483 The lateral thoracic artery axial pattern flap has been outlined on the skin. The ventral margin can be extended to the midline if necessary. 484 After incising the skin and undermining the flap, a bridging incision has been made and the flap rotated into the defect. 485 The subcutaneous tissues of the flap, recipient site and donor site have been apposed using absorbable monofilament suture material. 486 The skin has been closed in an interrupted pattern using nonabsorbable monofilament suture material. drawn in the donor area using the landmarks described above (483). A skin incision is made, starting at the ventral border of the outlined flap. The flap is then undermined, starting dorsally and working towards the cranioventral base of the flap. Stay sutures are placed in the corners of the flap to helprotate it into the defect on the forelimb (484). The subcutaneous tissues of the flap are apposed to the edges of the defect using absorbable monofilament suture material. The subcutis of the donor site is closed in a continuous or interrupted pattern (over a Penrose drain when needed) using absorbable monofilament suture material (485). The skin is closed using staples or simple inter - rupted sutures of nonabsorbable suture material (486). References Benzioni H, Shahar R, Yudelevich S et al. (2009) Lateral thoracic artery axial pattern flap in cats. Vet Surg 38:112–116. Pavletic MM (2010) Atlas of Small Animal Wound Management and Reconstructive Surgery, 3rd edn. Wiley–Blackwell, Ames. pp. 378–379. 483 484 485 486 Superficial brachial axial pattern flap Overview This axial pattern flap is used to cover antebrachial wounds and defects involving the elbow. A cutaneous branch of the superficial brachial artery supplies the craniomedial antebrachium. The cephalic vein runs on the lateral side of this vessel (487–489). Procedure The dog is positioned in dorsal recumbency. The forelimb should be extended so that the elbow joint is not flexed. The donor site, which consists of skin on the scapulohumeral joint, the cranial humerus and the elbow, is clipped and aseptically prepared. The flap area is cleaned and sterilized using routine procedures. If necessary, the defect is debrided. A flap should always be placed on a healthy granulation bed or fresh tissue. Epithelium from the wound edges is removed if necessary. Two parallel lines are drawn from the elbow joint to the greater tubercle of the humerus. The distance between the two lines corresponds with the width of the defect. It is important to ensure that the site can be closed without creating too much tension. The flap is progressively tapered as it approaches the greater tubercle. The length of flap required is determined by measuring from the pivot point bet - ween the defect and the flap (490). Incisions are made following the predrawn lines from the end to the base of the flap. The flap is then elevated and rotated laterally into the defect. If the flap is not long enough to cover the defect, it can be elongated by incising its base (491). A bridging incision is made to facilitate rotation of the flap. It also lengthens the flap (492). Stay sutures are used to manoeuvre the flap (493). Reconstructive techniques of the forelimb186 487–489 Schematic representation of the superficial brachial artery axial pattern flap. The coloured part of the dog depicts the estimated area that can be reached by the flap. 487 488 489 Reconstructive techniques of the forelimb 187 490 Dorsal view of the defect and the donor site. Note the pivot point (arrow). 491 The flap is assessed to determine if it is of the correct length. 492 A bridging incision is made to facilitate rotation of the flap. 493 The flap is rotated with the help of stay sutures so that it covers the defect. 490 491 492 493 The flap is partially sutured into place with 3-0 absorbable monofilament sutures at critical landmarks (494). The flap is then fully sutured into place with interrupted or continuous sutures of absorbable monofilament suture material for the subcutis and interrupted sutures of nonabsorbable monofilament suture material for the skin. If necessary a drain can be placed, which exits the wound at its most distal point. The donor site is closed with interrupted or continuous sutures of absorbable monofilament suture for the subcutis and interrupted sutures of nonabsorbable mono - filament material for the skin (495). References Done SH, Goody PC, Evans SA et al. (1996) (eds) Color Atlas of Veterinary Anatomy. Volume 3: the Dog and Cat. Mosby, St. Louis, p. 4.33 (fig. 4.56). Dyce KM, Sack WO, Wensing CJG (1996) Textbook of Veterinary Anatomy. WB Saunders, Philadelphia, p. 461. Fossum TW, Hedlund CS, Hulse DA et al. (2002) (eds) Small Animal Surgery, 2nd edn. Mosby, St. Louis, p. 171. Pavletic MM (2010) Atlas of Small Animal Wound Management and Reconstructive Surgery, 3rd edn. Wiley–Blackwell, Ames, pp. 380–382. Straw R (2007) Reconstructive surgery in veterinary cancer treatment. In: Proceedings of the World Small Animal Veterinary Association Congress, Sydney. Reconstructive techniques of the forelimb188 495 A dorsal view of the closed defect and donor site is shown. 494 The flap has been partially attached to the defect with sutures placed at the base of the defect. 494 495 Axillary (forelimb) fold flap Overview An axillary fold flap is used for the closure of wounds on the lateral and ventral aspect of the thorax (496, 497). Procedure The dog is positioned in lateral recumbency, making sure that the donor site and the defect site are easily accessible. When suturing the flap onto the defect, the dog can either be kept in lateral recumbency while the forelimb is extended abaxially or be placed in dorsal recumbency (498, 499). The donor site and defect are clipped and aseptically prepared. This includes the trunk at the base of the limb, the shoulder area and the proximal part of the forelimb. The distal part of the limb is covered with a sterile bandage. The defect is debrided if necessary. A flap should always be placed on a healthy granulation bed or fresh tissue. The dimensions of the defect and the amount of skin that can be harvested to cover the defect are assessed. This can be done by grasping the loose skin from the body wall to the elbow. Reconstructive techniques of the forelimb 189 498 Medial view of the site where the defect will be created. Note the forelimb is stretched abaxially. 499 The amount of skin needed is being assessed. 498 499 496, 497 Schematic representation of the axillary (forelimb) fold flap. The coloured part of the dog depicts the estimated area that can be reached by the flap. 496 497 Harvesting too much skin will result in excessive tension on closure of the donor site. Flexing and extending the elbow while elevating the skin will outline the outer boundaries of loose skin (500). Two lines are drawn outlining the flap; one line is drawn on the medial aspect of the skin covering the humerus, the other on the lateral side. The lines are connected distally by a crescent-shaped line. The width of the flap should correspond to the width of the defect. Ideally, the width should be approximately 50% of the length of the flap. The base of the flap has to be sufficiently wide to allow perfusion via the subdermal plexus (501, 502). The skin is then incised along the marked lines (503). The flap is undermined so that it can be elevated from the triceps. Stay sutures using absorbable monofilament suture material are placed at the distal end of the flap so that it can be transposed into the defect (504). Before the flap is secured in place, the distance that has been created is spanned by rotating the flap medially. The proximal tip of skin and the skin at the far side of the former flap base is apposed with a single suture (505). The flap is attached to the recipient bed using two interrupted subcutaneous sutures (506). The flap is then further sutured to the subcutis using absorbable monofilament suture material; if necessary, walk ing sutures and a Penrose drain can be used (507). The skin is closed with interrupted sutures using nonabsorbable monofilament suture material (508). Reconstructive techniques of the forelimb190 502 Lateral view of the donor site. The caudal part of the defect can be seen. 502 501 Caudal view of the site of the procedure. The limb is now stretched forward. 501 500 The defect has been created. 500 Reconstructive techniques of the forelimb 191 507 The flap has been sutured to the subcutis of the defect. 508 The skin of the flap and the surrounding tissue have been apposed. 504 The flap has been transposed into the defect. 506 The flap has been partially attached.505 The gap has been spanned with a single suture apposing the proximal tip of skin and the skin at the far sideof the former flap base. 504 505 506 507 508 503 An incision has been made on the lateral aspect of the donor flap. 503 The donor site is closed in two layers: the sub - cutaneous layer with interrupted or continuous sutures using absorbable monofilament suture mat - erial and the cutaneous layer with interrupted sutures using nonabsorbable monofilament suture material (509–511). The final result of this flap procedure is shown in a dog with a lesion near the elbow (512, 513). References Fossum TW, Hedlund CS, Hulse DA et al. (2002) (eds) Small Animal Surgery, 2nd edn. Mosby, St. Louis, pp. 166–167. Reconstructive techniques of the forelimb192 512, 513 An axillary fold flap has been performed on a dog with a defect on its forearm. 512 513 509 The donor site has been closed in two layers. 510 Medial view of the completed procedure. Note that the dog ear on the elbow has not yet been excised. 511 Lateral view of the transposed flap and the donor site. 509 510 511 Hunt GB (1995) Skin fold advancement flaps for closing large sternal and inguinal wounds in cats and dogs. Vet Surg 24:172–175. Hunt GB, Tisdall PLC, Liptak JM et al. (2001) Skin fold advancement flaps for closing large proximal limb and trunk defects in dogs and cats. Vet Surg 30:440–448. Pavletic MM (2010) Atlas of Small Animal Wound Management and Reconstructive Surgery, 3rd edn. Wiley–Blackwell, Ames, pp. 334–335. Reconstructive techniques of the forelimb 193 Flexor carpi ulnaris muscle flap Overview A flexor carpi ulnaris muscle flap involves the humeral head of the flexor carpi ulnaris. It is used in cases of chronic wounds involving the antebrachial, carpal and metacarpal areas. The origin of the muscle is the medial humeral epicondyl and its insertion is the accessory carpal bone. In this way, the flexor carpi ulnaris flexes the carpus. The humeral head of the flexor carpi ulnaris muscle is vascularized by the caudal interosseous artery, which enters the muscle at the distal tendon (514–516). Procedure The dog is positioned in lateral recumbency. The donor site, including the elbow and carpus, is clipped. The flap area is then cleaned and aseptically prepared using routine procedures. The defect is debrided if necessary. The flap should always be placed on a healthy granulation bed or fresh tissue. Epithelium is removed from the wound edges if necessary. A sterile glove can be used to cover the paw (517). An incision is made along the caudolateral aspect of the antebrachium, starting below the elbow and extending distally to 2 cm distal to the accessory carpal bone (518). 514–516 Schematic representation of the flexor carpi ulnaris muscle flap. The coloured part of the dog depicts the estimated area that can be reached by the flap. 514 515 516 517 Dorsolateral view of the site of the defect and the upper forelimb. 518 An incision has been made along the caudolateral aspect of the antebrachium. 517 518 The ante brachial and carpal fascia are incised in order to expose the humeral head of the flexor carpi ulnaris (519, 520). The ulnar head of the flexor carpi ulnaris is transected at its distal tendon to expose the humeral head (521). The humeral head of the flexor carpi ulnaris muscle can be identified between the ulnaris lateralis muscle laterally and the ulnar head of the flexor carpi ulnaris muscle caudally (522). After blunt dissection of the fascial attachments of the humeral head, the flexor carpi ulnaris muscle is transected between its proximal and middle parts (523). A bridging incision is made between the donor site and the recipient site and the muscle is then rotated into the wound (524). The flap is sutured into the defect with interrupted or continuous sutures of absorbable monofilament suture material. If the flap is to be closed using adjacent skin, the skin is undermined and walking sutures may be placed in the subcutaneous tissue to facilitate closure (525, 526). The ulnar tendon is attached to its head with interrupted sutures or a specific tendon suture pattern using absorbable monofilament suture material (527, 528). A drain can be placed if needed. If the muscle flap cannot be covered by skin, a wet bandage is placed over the surface of the muscle. After 2 weeks, granulation tissue will have formed and the wound can be closed primarily with a free skin graft. References Chambers JN, Purinton PT, Allen SW et al. (1998) Flexor carpi ulnaris (humeral head) muscle flap for reconstruction of distal forelimb injuries in two dogs. Vet Surg 27:342. Done SH, Goody PC, Evans SA et al. (1996) (eds) Color Atlas of Veterinary Anatomy. Volume 3: the Dog and Cat. Mosby, St Louis, p. 4.28 (fig. 4.47). Dyce KM, Sack WO, Wensing CJG (1996) Textbook of Veterinary Anatomy. WB Saunders, Philadelphia, p. 86. Fossum TW, Hedlund CS, Hulse DA et al. (2002) (eds) Small Animal Surgery, 2nd edn. Mosby, St. Louis, pp. 178–179. Szentimrey D (1998) Principles of reconstructive surgery for the tumor patient. Clin Tech Small Anim Pract 13:70–76. Reconstructive techniques of the forelimb194 519 After incising the skin, the fascia is exposed. 520 View of the ulnar head of the flexor carpi ulnaris muscle after incision of the fascia. 521 Transection of the distal tendon of the ulnar head of the flexor carpi ulnaris muscle. 519 520 521 Reconstructive techniques of the forelimb 195 522 Dissection of the humeral head of flexor carpi ulnaris muscle. 523 Transection of the humeral head of the flexor carpi ulnaris muscle between the proximal and middle third of the muscle. 524 The site of the defect is connected to the flap area with a bridging incision. 522 523 524 527 Interrupted sutures are used to attach the ulnar tendon to its head. 528 The skin has been closed using nonabsorbable monofilament suture material. 525 The flap is rotated into the defect. 526 Walking sutures may be necessary to facilitate approximation of the subcutis. 525 526 527 528 Phalangeal fillet (digit I or dewclaw [P- i]) Overview Wounds on the dorsal aspect of the carpal and metacarpal region can be covered using local ad - vancement flaps or a flexor carpi ulnaris muscle flap. Small wounds distal to the carpus on the palmar or lateral aspect of the claw can be covered with a phalangeal fillet flap using the skin of the thumb (P-1) (529–531). Procedure The dog is positioned in lateral recumbency to allow access to the medial aspect of the affected limb. The distal part of the limb is clipped. The flap area is cleaned and aseptically prepared using routine procedures. The defect is debrided if necessary. The flap should be placed on a healthy granulation bed or fresh tissue. Epithelium, if any, is removed from the wound edges (532). A No. 11 scalpel blade is used to make a circular incision around the base of the nail (533–535). Reconstructive techniques of the forelimb196 532 Medial view of the defect. 533 A circular incision is made around the nail bed. 529–531 Schematic representation of the phalangeal filet (P- I) flap. The coloured part of the dog depicts the estimated area that can be reached by the flap. 532 533 530 531529 534 The skin around the nail has been incised. 534 Reconstructive techniques of the forelimb 197 The skin of the thumb is incised along the predrawn lines (536, 537). The nail is then carefully dissected. The artery and vein that supply the thumb are ligated using absorbable monofilament suture material, or they can be cauterized. The phalanx and the metacarpal bone are removed (538). 535 The borders of the flap have been drawn. 538 The donor area is shown after removal of the thumb. 536 The first incision has been made. 537 The thumb is dislocated and amputated. 535 536 537 538 The caudolateral dotted line is incised and a bridging incision made to facilitate rotation of the flap into the area of the defect (539). The flap is rotated into the defect (540). The subcutis of the flap is sutured with interrupted or continuous sutures using absorbable monofilament suturematerial (541, 542). The skin is closed with interrupted sutures using nonabsorbable monofilament suture material (543). References Bradley DM, Shealy PM, Swaim SF (1993) Meshed skin graft and phalangeal fillet for paw salvage: a case report. J Am Anim Hosp Assoc 29:427–433. Done SH, Goody PC, Evans SA et al. (1996) (eds) Color Atlas of Veterinary Anatomy. Volume 3: the Dog and Cat. Mosby, St Louis, p. 4.41 (fig. 4.73). Dyce KM, Sack WO, Wensing CJG (1996) (eds) Textbook of Veterinary Anatomy. WB Saunders, Philadelphia, pp. 79, 462–463. Fossum TW, Hedlund CS, Hulse DA et al. (2002) (eds) Small Animal Surgery, 2nd edn. Mosby, St. Louis, pp. 206–208. Slatter D (2003) Textbook of Small Animal Surgery, Volume 2. WB Saunders, Philadelphia, p. 1987. Swaim SF, Henderson RA (1997) (eds) Small Animal Wound Management, 2nd edn. Williams & Wilkins, Philadelphia, pp. 342, 352. Reconstructive techniques of the forelimb198 Reconstructive techniques of the forelimb 199 542 The subcutis has been apposed. 543 The skin has been closed. 540 The flap is being rotated into the defect. 541 The flap is sutured into the defect. 540 541 542 543 539 The caudolateral line has been incised and a bridging incision made. 539 Phalangeal fillet (Digits II–IV) Overview Phalangeal fillets are used to close defects of the phalanges and paws. They can be used to cover de - fects on the other phalanges or on the dorsum of the paw. Procedure The animal is positioned in lateral recumbency. The medial and lateral aspects of the distal limb and the area around the toes and the defect are clipped. The affected area is carefully cleaned and debrided and an assessment made of which pha lanx needs to be removed (544). An incision is made on the dorsal aspect of the paw, in the skin between the two toes, from proximal to distal. It is then extended to the plantar aspect of the digit (545, 546). The dorsal vasculature is ligated (547). The proximal phalangeal bone (phalanx I) and tendons are then removed. The bones in the digit are re - moved by careful dissection as close to the bones as possible (548–550). Next, the distal phalanx and the nail (phalanx III) are removed (551) and, finally, the middle phalangeal bone (phalanx II) and tendons are excised (552) . Reconstructive techniques of the forelimb200 544 The area of the defect has been cleaned and debrided. 545, 546 An incision has been made on the dorsal aspect of the paw (545) and extended to the plantar aspect of the digit (546). 547 The vasculature is ligated. 547 544 545 546 Reconstructive techniques of the forelimb 201 548–550 The proximal phalangeal bone (phalanx I) and tendons are removed. The bones in the digit are removed by careful dissection as close to the bones as possible. 548 549 550 551, 552 The distal phalanx and the nail (phalanx III) are removed (551) and the middle phalangeal bone (phalanx II) is excised (552). 551 552 The flap is trimmed to the appropriate size (553–555). The flap is kept in one piece in order to cover the dorsum of the paw. The flap is sutured using a few sutures of absorbable monofilament suture material in the subcutis (556–558). The subcutis is closed in a continuous pattern using absorbable suture material and the skin is closed in an interrupted pattern using nonabsorbable monofilament suture material (559, 560). References Barclay CG, Fowler JD, Basher AW (1987) Use of the carpal pad to salvage the forelimb in a dog and cat: an alternative to total limb amputation. J Am Anim Hosp Assoc 23:527–532. Basher AWP, Fowler JD, Bowen CVA et al. (1990) Microneurovascular free digital pad transfer in the dog. Vet Surg 19:226–231. Demetriou JL, Shales JC, Hamilton MH et al. (1990) Reconstruction of a nonhealing lick granuloma in a dog using a phalangeal fillet technique. J Am Anim Hosp Assoc 43:288–291. Fowler D (2006) Distal limb and paw injuries. Vet Clin North Am Small Anim Pract 36:819–845. Gourley IM (1978) Neurovascular island flap for treatment of trophic metacarpal pad ulcer in the dog. J Am Vet Med Assoc 14:119–125. Pavletic MM (2010) Atlas of Small Animal Wound Management and Reconstructive Surgery, 3rd edn. Wiley–Blackwell, Ames, pp. 538–545. Swaim FS, Garret PD (1985) Foot salvage techniques in dogs and cats: options, do’s and don’ts. J Am Anim Hosp Assoc 21:511–519. Swaim SF, Henderson RA (1997) (eds) Small Animal Wound Management, 2nd edn. Williams & Wilkins, Philadelphia, pp. 342–346. Reconstructive techniques of the forelimb202 553 The flap is trimmed. 555 An overview of the flap is shown. 553 554 555 554 A bridging incision is made at the distal end of the flap. Reconstructive techniques of the forelimb 203 559 The skin is closed with nonabsorbable monofilament suture material. 560 The closed skin is shown. 559 560 556–558 The flap is sutured into the defect. 556 557 558 Fusion podoplasty Overview Fusion podoplasty is recommended in cases of severe pododermatitis that are not responsive to medical treatment. All the skin between the toes and pads is removed and the toes and pads are sut - ured together to form one ‘foot’. Reconstructive techniques of the forelimb204 Procedure The animal is positioned in lateral recumbency. The distal limb is clipped and shaved. The skin between the digits should be clipped carefully. The distal paw is cleaned and aseptically prepared using routine procedures. A line is drawn on the skin between the digits to mark which portion should be removed (561, 562). The portion of skin to be removed on the abaxial sides of the third and fourth digits is shorter than on the axial side (563). A line is then drawn to mark the portion of the skin that has to be removed on the palmar side, between the digital pads and the metatarsal/ metacarpal pad (564). The skin between the digits is then removed (565–567) and the skin on the plantar aspect of the paw is also removed (568, 569). 561, 562 The portion of skin that is to be removed has been marked. A piece of skin as long as the adjacent digit should be removed. 563 The outline of the skin between digits three and four is shown. 561 562 563 Reconstructive techniques of the forelimb 205 567 All the skin on the dorsal side of the paw has now been removed. 569 The foot is shown after all the skin has been removed.568 All the skin on the plantar side of the paw has been removed. 565 The skin between digits two and three has been removed. 566 The skin between digits three and four has also been removed. 565 566 567 568 569 564 The plantar outline of the skin to be removed is shown. 564 The digital pads and the metatarsal/metacarpal pad are sutured together using absorbable monofilament suture material (570–572). The subcutis is closed on the dorsal aspect of the paw in a continuous pattern using absorbable mono - filament suture material. The skin on the dorsum of the paw is closed in an interrupted suture pattern (573). Placement of a drain is not necessary with this procedure. References Fowler D (2006) Distal limb and paw injuries. Vet Clin North Am Small Anim. Pract 36:819–845. Gregory C, Gourley IM (1990) Use of flap and or grafts for repair of skin defects of the distal limb of the dog and cat. Prob Vet Med 2:424–432. Pavletic MM (2010) Atlas of Small Animal Wound Management and Reconstructive Surgery, 3rd edn. Wiley–Blackwell, Ames, pp. 538–545. Swaim FS, Garret PD (1985) Foot salvage techniques in dogs and cats: options, do’s and don’ts. J Am Anim Hosp Assoc 21:511–519. Swaim SF, Henderson RA (1997) (eds) Small Animal Wound Management, 2nd edn. Williams & Wilkins, Philadelphia, pp. 364–369. Reconstructive techniques of the forelimb206 570, 571 The second digital pad (570) and the fifth digital pad (571) have been sutured onto the metacarpal pad. 573 The skin on the dorsum of the paw has been closed using an interrupted suture pattern. 572 All the pads have now been sutured together. 570 571 572 573 Reconstructive techniques of the forelimb 207 Segmental pad transfer Overview