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Revue Méd. Vét., 2009, 160, 8-9, 404-409 Introduction Diarrhoea is characterized by the more frequent production of faeces that are wet and soft (less than 10% dry content). This clinical sign is easy to diagnose but non specific. Effectively, it is encountered in a number of diseases of the young animal, which are due to several agents: these agents can act concomitantly to produce the disease in the calf. Often, this group of diseases is named “enteritis”, although classical inflammation of the mucosa may not be present. For instance, when diarrhoea is associated with enterotoxi- genic strains of E. coli, there is mainly a large net increase of secretion due to enterotoxins, with minor lesions of the gut mucosa. Diarrhoea is the most important disease of neonatal calves and results in the greatest economic loss due to disease in this age group in both dairy and beef calves. Outbreaks of neonatal calf diarrhoea (NCD) can be indeed costly, espe- cially for beef producers, as treatment of affected calves is time consuming, and the death of a calf represents the loss of profit from that cow–calf unit for the year. Additionally for survivors there may be impacts on subsequent calf growth rate and weaning weight, loss of genetic potential and a decreased capacity to improve and maintain the herd. NCD is generally observed together with other clinical signs, among them essentially dehydration with acid-base imbalance. Dysentery or even abdominal pain (colic) can be seen. All this depends on the cause of diarrhoea, on the pathogenesis (enteritis, malabsorption…), on the location and severity of corresponding lesions… At the individual level, the precise diagnosis is not always indispensable, because it does not affect the course of actions to take (generally urgent rehydration followed by a number of hygienic measures and supportive treatment). But at the herd level, diagnosis is important, and it has consequences in question of applied treatment or vaccination. Aetiological diagnosis of calf scours has to be made as rapidly as possible. Effectively, as infectious agents are generally implicated, it is of importance to check what agent(s) is (are) circulating in the herd and is/are mainly determining the obs- erved outbreak. An adapted treatment may be proposed after diagnosis and above all the diagnosis may help defining an adapted prophylaxis based on vaccination of dams or calves as well as modification of management of the herd in the areas of feeding, control of parasitism, etc. Finally it is also of importance to check whether the outbreak is due to a zoonotic pathogen such as Salmonella, Campylobacter… SUMMARY Neonatal calf diarrhoea (NCD) is the most important disease of neonatal calves and results in the greatest economic losses due to disease in this age group in both dairy and beef calves. NCD outbreak associated costs include treatment time, possible impact on subsequent calf growth performances and potential death. NCD results from a combination of an adverse envi- ronment, poor host immunity and challenge from infectious agents. While an etiological diagnosis in NCD cases may not be relevant for the treatment of the individual, such diagnosis helps determining which adapted measures can be taken on herd level especially if zoonotic pathogens are involved. The clinical diagnosis should be based on the clinical picture including the age of the affected animals and associated clinical signs collated through a thorough physical examination together with epidemiological data inclu- ding the season and herd history. In most situations, the clinical diagnosis requires confirmation by on-farm or laboratory tests. Keywords: Calf, diarrhoea, diagnosis, herd, epidemiology, clinical signs, confirmation, laboratory. RÉSUMÉ Diagnostic des diarrhées néonatales du veau Les diarrhées néonatales du veau constituent la maladie la plus importante des veaux nouveau-nés, entraînant les pertes économiques les plus élevées dans cette classe d’âge, tant chez les veaux laitiers que chez les veaux allai- tants. Les coûts associés aux diarrhées néonatales du veau comprennent le temps dévolu au traitement, l’impact possible sur les performances de crois- sance du veau et la mortalité. Les diarrhées néonatales du veau résultent de la combinaison de facteurs environnementaux défavorables, d’une immunité faible de l’hôte et d’agents infectieux. Alors qu’un diagnostic étiologique des cas de diarrhées néonatales se révèle peu important sur le plan du trai- tement individuel, en revanche il aide à déterminer quelles sont les mesures adaptées à prendre au niveau du troupeau, surtout si des agents zoonotiques sont impliqués. Le diagnostic clinique devrait être fondé sur les données cli- niques, comprenant l’âge des animaux atteints et les symptômes associés relevés grâce à un examen clinique consciencieux, ainsi que des données épidémiologiques incluant la saison, et l’historique du troupeau. Dans la plupart des situations, le diagnostic clinique requiert une confirmation par des tests réalisables dans la ferme ou avec l’aide du laboratoire. Mots clés : Veau, diarrhée, diagnostic, troupeau, épidé- miologie, signes cliniques, confirmation, laboratoire. Diagnosis of neonatal calf diarrhoea Y. MILLEMANN* Pathologie du Bétail, Ecole Nationale Vétérinaire d’Alfort, 7 avenue du général de Gaulle, 94704 Maisons-Alfort cedex, FRANCE. *Corresponding author: ymillemann@vet-alfort.fr Cet article a fait l’objet d’une communication au 4ème “Dairy Solutions Symposium” les 25 et 26 septembre 2008, Lasalle Beauvais, FRANCE. Revue Méd. Vét., 2009, 160, 8-9, 404-409 DIAGNOSIS OF NEONATAL CALF DIARRHOEA 405 Therefore, in order to adapt therapeutics and prophylactic advices, it is of importance to search for the precise aetiology of the observed digestive disorders. Epidemiology Neonatal calf diarrhoea (NCD) occurs mainly in calves less than six weeks of age, although calves up to four months of age may be affected. It can affect beef as well as dairy cal- ves. It occurs mainly also during the winter period and when animals are within stables [5]. Lots of animals can be affec- ted: for instance, in a French study on beef calves, the mean incidence rate for diarrhoea during the neonatal period was 14.6%, with herds having an incidence over 50% [2]. During the winter season, the number of diarrhoeic calves increases often together with the severity of the disease. This is linked to the fact that the infection pressure for neonates tends to increase progressively. A number of key points can explain this phenomenon. First, all major enteric pathogens are commonly carried by asymptomatic adult cows and shedding of many pathogens species tends to increase around calving. Second, healthy calves are often asympto- matically or subclinically infected with enteric pathogens and amplify environmental contamination. Finally, all major enteric pathogens can survive in the environment and water sources for weeks to months (and in most cases over a year) in cool, damp conditions. Many other animals, including feral animals and domestic pets, can also contribute to the contamination of calves by pathogens like Cryptosporidium, Salmonella or rotavirus. Because of its essential infectious aetiology, NCD incidence increases in herds where infection pressure increases and in herds where calves have an inadequate immunity: this can be due to a failure of transfer of colostral immunity or to stres- sing factors like a cold weather [1, 16]. Aetiology NCD is a multifactorial disease and results from a combi- nation of an adverse environment, poor host immunity and challenge from infectious agents [1, 16]. Although a very serious impairment in any one of these factors can lead to disease, NCD outbreaks usually reflect a problem in all three areas. Consequently it is importantto address the problem at a herd level by assessing risk factors and implementing pre- ventive management. ADVERSE ENVIRONMENT Adverse conditions in the environment of the neonate can contribute to the emergence of diarrheal outbreaks. For instance, a cold winter with air drafts falling on calves, a wet litter, a litter made of granite fines are risk factors associated with NCD [15]. Indeed, environment of neonates is a key factor in the emergence of diarrhoea: housing with abundant straw bedding, nature of the pen walls, air volume per animal [12]… Also, the absence of cohabitation with animals of other age classes is important to control. One must not forget that diarrhoea may have also a nutri- tional origin. This can be linked to the distribution of raw milk at unsuitable temperatures, or of too large quantities (over 3 L per meal). This can be linked also to the use of milk replacers of inferior quality, or badly prepared (with lumps…). All this can lead to the appearance of diarrhoea in the calves, with often great quantities of soft faeces. But, initially, there is no or minimal systemic effect… until there is superinfection by a pathogen. POOR HOST IMMUNITY A poor immunity in neonatal calves is essentially linked to a failure of passive transfer (FPT) of colostral antibodies. This may be due to an insufficient or delayed ingestion of colostrum by the neonate or to a poor quality of the colos- trum [11, 13-14]. Adequate ingestion of the colostrum by the neonate can be easily controlled by a careful farmer. Colos- trum quality can be checked with a colostrometer; this quality is conditioned by the parity and the sanitary status of the dam, linked to the control of parasitism, the nutrition, the season [9]… CHALLENGE FROM INFECTIOUS AGENTS Several pathogenic agents can, alone or, most often, in combination, determine diarrhoea in the young calf. These agents can also act successively in the same calf: this can explain discrepant laboratory results of successive analyses for a single calf or between calves in the same herd. Enteropathogenic agents are usually present in the environ- ment of the calves or are carried and shed by the dam or other animals from the herd: sick or convalescent animals, asymptomatic carriers [5, 18]… During calving season, the concentration of pathogens in the environment increases pro- gressively, with an amplification by the first calves of the season. This increases infectious pressure, and, associated with favourable conditions, this leads to a degradation of the health of calves and to the emergence of real neonatal diar- rhoea epizootics. The main agents responsible for diarrhoea in the calf [16] (Table I) are bacteria (mainly Escherichia coli strains, Table II), parasites (essentially Cryptosporidia) and finally viruses (among them particularly rotaviruses and to a less extent coronaviruses). Enteropathogenic agents are very frequently isolated from faeces of diarrhoeic calves that were not preliminarily trea- ted with antibiotics, E. coli being the commonest. E. coli is isolated alone in half of the cases but a sequential action of several agents can not be excluded. In other cases, E. coli is isolated along with other agents: most often associated pathogens are by decreasing importance cryptosporidia, rota- viruses, coronaviruses, and toroviruses [5, 6, 10]. Finally an essential point must be underlined: whatever the responsible pathogen(s), diarrhoea is frequently associated in Revue Méd. Vét., 2009, 160, 8-9, 404-409 406 MILLEMANN (Y.) the young calf (from the birth to 3-4 weeks of age) to a toxaemia and/or a septicaemia that complicate the disease and worsen the prognosis. Clinical diagnosis Practical diagnosis will first rest on the thorough clinical examination of affected calves, together with a precise anamnesis. The aspect of diarrhoea can help orientating the diagnosis, which will be based on associated signs as well as the age of the affected animals (Table III). Effectively, each neonatal disease characterised by diarrhoea in the calf has its peak incidence at a specific age (Figure 1). Colibacillosis is generally Bacteria Viruses Parasites E. coli : ETEC, EPEC, EHEC Rotavirus Cryptosporidium Salmonella Coronavirus Giardia Clostridium Torovirus (Breda) Eimeria bovis, or zuernii (animals over 3 weeks) Campylobacter BVDV/MDV Candida Calicivirus (norovirus)… Toxocara Strongyloides TABLE I: Main pathogenic agents responsible for diarrhoea in the calf (non exhaustive list). Bold characters underline the most often encountered pathogens. Pathotype ETEC (entero-toxigenic E. coli) VTEC (vero-toxigenic E. coli)a EPEC (entero-pathogenic E. coli)b Age of affected calves < 5 days 1 to 3 weeks 1 to 3 weeks Adhesins K99 (F5), F41, FY Intimin (Eae) BFP (“bundle forming pili”) (+/- CS31A) Intimin (Eae) Toxins STa (ST1) VT1 and VT2 (Stx1, Stx2) - TABLE II: Main Escherichia coli pathotypes responsible for calf diarrhoea and associated virulence factors [17, 23]. a mainly EHEC: enterohaemorrhagic E. coli; can be named STEC (shigatoxic E. coli). Responsible for HUS (haemolyitic and uremic syndrome) in the child under 5 years, mainly serotype O157:H7. b mainly AEEC: adhering-effacing E. coli. Mean age of affected calves Clinical signs Probable aetiological diagnosis 1-3 days Very liquid diarrhoea, yellow Colibacillosis (ETEC = F5 E. coli) Rapid and important dehydration (eyes sunkness, diminished skin elasticity) Weakness, cold extremities 4-11 days Mucoid diarrhoea Rotavirosis, coronavirosis, cryptosporidiosis Hyperthermia Anorexia, abdominal pain Progressive dehydration > 11 days Very liquid diarrhoea with blood traces Salmonellosis Severe hyperthermia (> 41°C) > 18 days Black diarrhoea, +/- blood and colic Coccidiosis due to Eimeria zuernii Mucoid diarrhoea, hyperthermia Bovine viral diarrhoea Ptyalism, anorexia, epiphora TABLE III: Helpful elements for the differential diagnosis of NCD. FIGURE 1: Incidence of the causes of diarrhoea according to the age of calves (adapted from [18]). Revue Méd. Vét., 2009, 160, 8-9, 404-409 DIAGNOSIS OF NEONATAL CALF DIARRHOEA 407 encountered in very young calves (under 5 days) while coc- cidiosis (eimeriosis) will affect preferentially calves over 3 weeks. Because of the pathogenic course of diarrhoea, the affected animal will generally experience dehydration together with a more or less severe acidosis linked to either faecal losses of bicarbonate or L-lactate production following dehydration or D-lactate production by Lactobacilli. The age of the calf plays a great role in the susceptibility of the calf to the diar- rhoea. Dehydration and acidosis (especially D-lactic acidosis occurring in the “diarrhea without dehydration syndrome” in 10-day-old calves) have systemic consequences and lead to depression, recumbency, or even cardiac or renal failure… Hypothermia or cachexy may also been observed in affected calves. Together with the age of the affected calf, the observed systemic effects and their severity can orientate the practitio- ner towards the suspected responsible enteropathogen. For instance, a marked hyperthermia (> 40.5-41°C) may lead to a suspicion of colibacillosis, salmonellosis or coronavirosis, as well as a high mortality of affected calves. By contrast, a low mortality is rather evocative of rotavirosis. We may note also that the absence or presence of hyperthermia in the affected calf determines the choice for the adapted treatment, taking into account the responsible and prudent use of anti- biotics [4]. When NCD is accompanied by mortality, the practitioner can obtain interesting hints by realising a necropsic examination: observed lesions and samples can be very helpful to determine the aetiological agent. Necropsy will also aid evidencing the possible implication of thesuspected pathogen in the diarrheal episode: one must keep in mind that the presence of an ente- ropathogen in an affected calf is not enough to prove its role in the pathogenic process. Indeed, asymptomatic carriers and shed- ders exist, and the evidence of associated lesions is necessary to demonstrate the implication of a suspected pathogen. Paraclinical diagnosis The clinical examination in the farm leads to a suspicion towards the implicated pathogen, together with a number of risk factors contributing to the outbreak. The practitioner needs afterwards to confirm his suspicion with the help of laboratory tests (Table IV). Among them, several can be carried out by the practitioner in the field or in his clinic (Table V). Moreover, when faced to an outbreak of NCD in a herd one must verify FPT by measuring gamma-globulinemia in calves [13, 14, 20, 22]. A number of dedicated commercial tests that can be carried out in the field is today available (Table V, first lines). Once the FPT is diagnosed, the practi- tioner will help improving the passive transfer of immuno- globulins in calves [7, 8]. Agent Sample Carried out method - observations E. coli Faeces, intestinal content Elisa « BVT » Culture then slide agglutination (F5, F41, F17, CS31A) Antibiotic resistance profile. Search for genes specific for septicaemic E. coli [19] Salmonella Faeces; on dead animal: ileo-colon, Culture, then antibiotic resistance profiling and serotyping mesenteric lymphatic nodes, spleen, Serology: no diagnostic interest liver (aborted foetus) Clostridium Faeces, intestinal content (hermetically sealed Culture and enumeration flacon), 4°C, brief delay for analysis Possible search for genes coding for toxins (PCR) Do not forget C. difficile ? [21] Rotavirus Faeces; on dead animal: ileon Elisa « BVT » Immuno-enzymatic search, latex test Pb: only group A rotaviruses Coronavirus Faeces; on dead animal: ileo-colon Elisa « BVT » Immuno-enzymatic search, agar immuno-diffusion Sensitivity 106 PFU /g Adénovirus Faeces Human ELISA kits useful [3] Calicivirus Faeces RT-PCR for identification [24] based on group primers Human ELISA kit useful because of the antigenic community. Torovirus Faeces ELISA and RT-PCR have been described [10]. Possible development of a multiplex RT PCR for cattle: calicivirus and adenovirus (+ astrovirus) Pestivirus BVD/MD Faeces: NO! Immuno-enzymatic test in 24h (Antigen), cellular culture Naso-pharyngeal lavage, blood (PI only); on (gold standard: 8-21d), immunofluorescence on organs dead animal: ileo-colon, lymphatic nodes, (1-3d delay) spleen, abomasum, rectum, lung (aborted foetus) Cryptosporidium Faeces Microscopic examination (Ziehl Neelsen, Heine…) Eimeria (bovis, zuernii) Faeces Microscopic examination TABLE IV: Samples to be done according to the suspected enteropathogen in face of calf diarrhoea. Revue Méd. Vét., 2009, 160, 8-9, 404-409 408 MILLEMANN (Y.) Conclusion In conclusion, NCD remains the most important disease in calves under 4 weeks, responsible for huge economical losses. Several enteropathogens can act successively or together to determine NCD in herds where risk factors are present, which impair the calf’s immunity and especially contribute to FPT. Although NCD is quite easy to identify, a precise aetiolo- gical diagnosis is difficult to carry out. It is indispensable in herds where the infection pressure increases, to adapt the treatment but also and above all the preventive measures. It is also useful when the suspected agent is of public health concern. In order to carry out a precise diagnosis, the practitioner needs first to carry out thoroughly a clinical examination of the affected animals: the age of affected calves, together with the aspect of the faeces and the associated clinical signs help to hypothesize what is the probable diagnosis. Afterwards, with the help of rapid tests that can be carried out in the farm or in the clinic, or even with the help of laboratory analyses or a precise necropsy, the diagnosis can be confirmed. References 1. - BARRINGTON G.M., GAY J.M., EVERMANN J.F.: Biosecurity for neonatal gastrointestinal diseases. Vet. Clin. North Am.: Food Anim. Pract., 2002, 18, 7-34. 2. - BENDALI F., BICHET H., SCHELCHER F., SANAA M.: Pattern of diarrhoea in newborn beef calves in south-west France. Vet. Res., 1999, 30, 61-74. 3. - BRENNER J., ELAD D., BERNSTEIN M., DAGONI I., PÁLFI V., YADIN H.: 2005. The detection of an unidentified type of adenovi- rus in the stools of calves with weak calf syndrome by use of a com- mercial kit designed for the detection of human adenoviruses. J. Vet. Med. B Infect. Dis. Vet. Public Health, 2005, 52, 98-101. 4. - CONSTABLE P.D.: Antimicrobial use in the treatment of calf diar- rhoea. J. Vet. Intern. Med., 2004, 18, 8-17. 5. - FRÉMONT A, CORNUEJOLS MJ, COUQUET C.: Enquête épidé- miologique sur les diarrhées néonatales. Point Vét., 2004, 35, 20-23. 6. - GARCIA A., RUIZ-SANTA-QUITERIA J.A., ORDEN J.A., CID D., SANZ R., GOMEZ-BAUTISTA M., DE LA FUENTE R.: Rotavirus and concurrent infections with other enteropathogens in neonatal diarrheic dairy calves in Spain. Comp. Immunol. Microbiol. Infect. Dis., 2000, 23, 175-183. 7. - GODDEN S.M., HAINES D.M., HAGMAN D.: Improving passive transfer of immunoglobulins in calves. I: dose effect of feeding a commercial colostrum replacer. J. Dairy Sci., 2009, 92, 1750-1757. 8. - GODDEN S.M., HAINES D.M., KONKOL K., PETERSON J.: Improving passive transfer of immunoglobulins in calves. II: interac- tion between feeding method and volume of colostrum fed. J. Dairy Sci., 2009, 92, 1758-1764. 9. - GULLIKSEN S.M., LIE K.I., SOLVEROD L., OSTERÅS O.: Risk factors associated with colostrum quality in Norwegian dairy cows. J. Dairy Sci., 2007, 91, 704-712. 10. - HOET A.E., SMILEY J., THOMAS C., NIELSEN P.R., WITTUM T.E., SAIF L.J.: Association of enteric shedding of bovine torovirus (Breda virus) and other enteropathogens with diarrhea in veal calves. Am. J. Vet. Res., 2003, 64, 485-490. 11. - LARSON R.L., TYLER J.W.: Reducing calf losses in beef herds. Vet. Clin. North Am.: Food Anim. Pract., 2005, 21, 569-584. 12. - LUNDBORG G.K., SVENSSON S.C., OLTENACU P.A.: Herd- level risk factors for infectious diseases in Swedish dairy calves aged 0–90 days. Prev. Vet. Med., 2005, 68, 123-143. 13. - MAILLARD R.: Composition et rôle du colostrum chez les bovins. Point Vét., 2006, 37, 106-109. 14. - MAILLARD R.: Le transfert de l’immunité colostrale chez le veau. Point Vét., 2006, 37, 110-114. 15. - MCGUIRK SM.: 2008. Disease management of dairy calves and heifers. Vet. Clin. North Am.: Food Anim. Pract., 2008, 24, 139-153. 16. - MILLEMANN Y, MAILLARD R. : 2007. Les agents entéropatho- gènes du veau. Point Vét., 2007, 38, 53-60. 17. - NAVETAT H.: Les gastro-entérites diarrhéiques du veau. Dép. Vét., 1999, Supplément technique 62, 1-25. 18. - NAYLOR J.M.: Neonatal ruminant diarrhea. In: Large animal internal medicine. Smith BP, editor. Mosby, St Louis, Missouri. 2002, 352-366. 19. - NICOLLET P., MAINGOURD C.: Nouveautés dans le diagnostic des colibacilloses du veau. Application d’une méthode d’identification des facteurs de pathogénicité par PCR multiplex au diagnostic des colibacilloses septicémiques. CR des JNGTV, 2007, 489-494. 20. - PARREÑO V., BÉJAR C., VAGNOZZI A., BARRANDEGUY M., COSTANTINI V., CRAIG M.I., YUAN L., HODGINS D., SAIF .L, Test (supplier) Sample Method / result Delay for obtention of results Bovine® IgG (Midland) Colostrum Immunochromatography 20 minutes Evidence of a quantitative failure of IgG secretion by the udder Calf® IgG (Midland) Total blood Evidence of a quantitative failure of IgG in the calf’s blood 20 minutes Speed® Giardia Faeces Immunochromatography 5 minutes (Bio Véto test) Evidence of Giardia duodenalis ookysts in a weight losssyndrome with intermittent diarrhoea in the young calf Speed® V diar 4 and Speed® Faeces Immunochromatography 15 minutes V diar 5 (Bio Véto test) Differential diagnosis of NCD for 4-5 agents (rota/coronavirus, C. parvum, E. coli K99, E. coli CS31A) Bio K 156 Faeces Immunochromatography 15 minutes « Tigettes tétravalentes » Differential diagnosis of NCD for 4 agents (virus, bacteria, (Bio-X Diagnostics) parasites) Bio K 195, Bio K 170, Faeces Diagnosis of, respectively, Clostridium perfringens and 15 minutes Bio K 176 (Bio-X Diagnostics) its α and ε toxins TABLE V: Available commercial tests helpful in the diagnosis of NCD. Revue Méd. Vét., 2009, 160, 8-9, 404-409 DIAGNOSIS OF NEONATAL CALF DIARRHOEA 409 FERNÁNDEZ F.: Modulation by colostrum-acquired maternal anti- bodies of systemic and mucosal antibody responses to rotavirus in calves experimentally challenged with bovine rotavirus. Vet. Immunol. Immunopathol. 2004, 100, 7-24. 21. - RODRIGUEZ-PALACIOS A., STÄMPFLI H.R., DUFFIELD T., PEREGRINE A.S., TROTZ-WILLIAMS L.A., ARROYO L.G., BRAZIER J.S., WEESE J.S.: Clostridium difficile PCR ribotypes in calves, Canada. Emerg. Infect. Dis., 2006, 12, 1730-1736. 22. - ROLLIN F.: Tools for a prompt cowside diagnosis: what can be implemented by the bovine practitioner? World’s Buiatrics Congress proceedings, 2006, Nice, France, 75-85. 23. - SCHELCHER F., DE RYCKE J., MARTEL J.L., VALARCHER J.F., ESPINASSE J.J.: Diarrhées colibacillaires néonatales du veau. Point Vét., 1993, 25, 19-32. 24. - SMILEY J.R., HOET A.E., TRÅVÉN M., TSUNEMITSU H., SAIF L.J.: Reverse transcription-PCR assays for detection of bovine enteric caliciviruses (BEC) and analysis of the genetic relationships among BEC and human caliciviruses. J. Clin. Microbiol., 2003, 41, 3089-3099.
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