Revisão sistemática prebióticos Gatos

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The impact of prebiotics on cat food: a review 
 
 
 
PAMPLONA
1¶
, M. P.; PRINCIPE
1
, L.; MARCHI
1
, P. H., V.; R. A.; BRUNETTO
1*
, M. A. 
 
 
 
 
1
Center for Research in Dog and Cat Nutrology, University of São Paulo, São Paulo, SP, Brazil. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
*Corresponding author 
E-mail: mabrunetto@usp.br 
 
 
¶These authors contributed equally to this work. 
&These authors also contributed equally to this work. 
 
 
 
 
 
 
 
 
 
 
 
Abstract 
 
The intake of functional foods has been increased recently to improve metabolism, body composition, and gut 
microbiota. Prebiotics stand out among functional foods due to their functionality in animal metabolism such 
as the proliferation of beneficial bacteria and the production of fecal fermentative products that aid in the 
health and integrity of the body. Prebiotics can be defined as dietary carbohydrates that resist digestive 
enzymes in cats and are fermentable by bacteria in the large intestine. However, due to the diversity of 
fermentable fiber types used in the catfood market, there are discussions about which prebiotic to use and in 
which concentrations. Thus, the aim of this review was to demonstrate the effects of different prebiotics in 
healthy cat food. Platforms such as Scopus, Embase, Pubmed, and Mendeley were accessed to trace all in vivo 
scientific articles that reported prebiotics for feeding adult cats or senior cats. After excluding duplicate articles 
and those without the evaluated criteria, we obtained a total of 14 articles. Our results demonstrated the 
diversity and concentrations of prebiotics in feeding healthy adult and senior cats. This is a review that brings 
out the importance and modulating effects of prebiotics in the diet of healthy cats. These effects help the 
gastrointestinal tract and modulation of the microbiota. This will support future studies in analyzing 
concentrations and sources of prebiotics with the timing of prebiotic intake in relation to their effects. In 
conclusion, prebiotic diversity stimulates beneficial bacteria in the gut microbiota, which reduces the 
proliferation of harmful bacteria. In addition, these substrates promote important modulations in the 
gastrointestinal tract that advantageously affect the health of cats. 
 
Key-words: Fibers, Feline, Fermentative products, Functional foods, intestinals promoters, intestinal health. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Introduction 
 
The intake of functional foods has been increased recently to improve metabolism, body 
composition, and gut microbiota in animals. Prebiotics stand out among functional foods as they are a 
substrate used by selective beneficial microorganisms to promote health (REGALADO-RENTERÍA et 
al., 2020), and modulate gut fermentative, fecal, and immunological parameters (NEDAEI et al., 
2019). The definition expands the concept of prebiotics to include non-carbohydrate substances, 
applications at sites in the body other than the gastrointestinal tract, and various categories other than 
food. Beneficial health effects must be documented for a substance to be considered a prebiotic. The 
consensus definition also applies to prebiotics for use by animals, in which strategies focused on the 
microbiota to maintain health and prevent disease are as relevant as for humans (GIBSON et al., 
2017). 
Prebiotics can be defined as dietary carbohydrates that resist digestive enzymes in animals and 
pass into the large intestine where they are fermented by bacteria. In other words, prebiotics are 
indigestible and are considered fermentable carbohydrates. Most plant ingredients in cat foods carry 
varying types and amounts of prebiotics. Wet foods may contain thickening agents with prebiotic 
properties, such as guar gum. The focus is on high purity prebiotics that are added to cat foods to 
support a claim of gut health. Cat foods that promise gut health primarily contain 
fructooligosaccharides (FOS), mannan oligosaccharides (MOS), xylo-oligosaccharides (XOS), inulin, 
and lactosucrose. These foods are generally intended to stimulate the growth of gut bacteria toward a 
healthier community and to aid in the cat's digestion. 
The action of the intestinal microbiota in the decomposition process of complex carbohydrates 
is a response to the diverse genetic set of active enzyme encoders present in the genome of these 
bacteria, with infinite enzymes capable of breaking down, biosynthesizing, and altering complex 
carbohydrates. The variety of carbohydrates that make up the diet and reach the colon triggers 
numerous stages of bacterial breakdown for efficient use of these macromolecules (BEDU-FERRARI 
et al., 2022). 
Studies show that prebiotics have the potential to alter nitrogen metabolism, with possible 
benefits to animal health and long-term clinical nutrition, as a result of the potential reduction of 
intestinal pH, ammonia production and urea concentration (DOS SANTOS FELSSNER et al., 2016). 
The literature provides limited information on the effects of prebiotics in cats, so more studies 
comparing their concentrations and accomplishments should be developed (BEYNEN, 2019). 
Currently, there is a great attention for the use of prebiotics as alternative strategies in cat feeding 
(CALABRÒ et al., 2020), due to their beneficial effects on diseases and health. 
 
 
 
 
 
Prebiotics 
Saccharomyces cerevisiae yeast (YAM) 
Yeasts of the genus Saccharomyces are classified as ascomycetous fungi belonging to the order 
Saccharomycetales and the family Saccharomycetaceae (KURTZMAN, 2011). Yeasts and their cell 
extracts have been recognized as safe supplements for human and animal diets by the Food and Drug 
Administration (MOON et al., 2020). These products contain about 14.0% in dry matter (DM) of 
mannan-oligosaccharides (MOS), 24.0% in DM of β-glucans, lipids, chitin, vitamins, and 30.77% to 
56.9% of proteins (COSTA, 2004) which are often linked to mannan. β-glucans and MOS are 
beneficial to the gut microbiota due to their ability to ferment in the large intestine and their ability to 
limit the proliferation of pathogenic bacteria. Studies have proven that β-glucans protect the body 
against viral, fungal and bacterial infections (LIU, 2011; BORCHANI et al. 2016). Glucans and β-
glucans have the ability to remain intact in the digestive tract and, due to their specific properties of 
water-holding capacity and emulsion stability, are frequently used in the food industry (MUSCO et al., 
2018). 
There are several ways of producing and drying yeast, which guarantee its preservation and 
composition. Most of the distilleries use the spray dryer drying method, because the maximum 
temperature reached is high and the contact time during the drying is shorter when compared to the 
rotary roller drying, in which the product obtained can present a better nutritional quality 
(SCAPINELLO et al.,1997). In spray drying the quick exposure of the material and the high 
temperature of operation guarantee the preservation of all its properties, especially the amino acids 
(ZANUTTO, et al. 1999). 
YAM is a single-celled eukaryosis, which converts carbohydrates into carbon dioxide and 
alcohols by fermentation. Yeasts are obtained from the production of bread and beer, or after the 
production of alcoholic beverages. Yeast extracts are obtained mechanically after autolysis by acid or 
alkaline hydrolysis and by enzymatic treatment (FREIMUND et al., 2003; MUSCO et al., 2018). As 
pointed out by Shurson (2018), animals have been fed yeast-containing products for over 100 years. 
However, in recent years, due to the need to limit the use of antibiotics, increasing interest has been 
directed towards the use of yeast and its products in animal nutrition, particularly in the pet food 
industry, which produces a wide range of diets and supplementscontaining yeast, as well as yeast cell 
wall, for both dogs and cats. Different species of Saccharomyces, in particular S. cerevisiae, are widely 
adopted as prebiotics in animal nutrition (MEDINA et al., 2002; ARIF et al., 2020; DE OLIVEIRA 
MATHEUS et al., 2021; SANTOS et al., 2022). Furthermore, in dogs with inflammatory bowel 
disease, yeast has been considered an important marker in the detection of this disease 
(ALLENSPACH et al., 2004). 
Some studies demonstrate the effects of the use of CS on the increase of animal growth, 
decrease of intestinal pH, avoiding the proliferation of bacteria with pathogenic potential (FERKET, 
2004), increase in immune resistance (HUNTER et al., 2002; MANTOVANI et al, 2007; NUNES et 
al., 2008), and improves the intestinal integrity (CARVER & WALKER, 1995), as well as balancing 
the microbiota of the gastrointestinal tract (OYOFO et al., 1989; SWANSON et al., 2002), resulting in 
better digestion and absorption of nutrients. 
 
Yeast Cell Wall (YCW) 
Numerous yeast products and feed ingredients are commercially produced and used extensively 
in animal feeds. Considerable research has been conducted to evaluate the animal growth potential and 
health benefits of adding yeast and its derivatives to feed. Yeast cell walls are concentrated sources of 
mannan-oligosaccharides (MOS), and various commercial feed additives (SHURSON, 2018). 
Studies show that yeast extract is composed of approximately 34-38% protein with levels of 
lysine 3.61%, methionine 0.78% and tryptophan 0.68% (WU et al, 2018), 5.0% glutamic acid 
(OLIVEIRA et al., 2016), 5.5% nucleotides (SOUZA et al., 2011), B vitamins, enzymes, short-chain 
fatty acids (CHFA) and chelated minerals (BUTOLO et al., 2010). The inclusion of yeast extract in 
dog and cat foods can assist in intestinal maintenance and performance (BILL KAELLE et al., 2022). 
 
Mannanoligosaccharides (MOS) 
Originating from compounds isolated from the cell wall of yeast, mamanoligosaccharides 
(MOS) are derived from the non-starch hemicellulose polysaccharide called mannan (JANA et al., 
2021) and have lower intestinal fermentation compared to FOS. MOS reduce the presence of 
pathogenic bacteria in the gut by being integrated into specific epithelial cell sites in the intestinal 
mucosa, and assist in modulating the immune system (SWANSON et al., 2002). 
 
Fructooligosaccharides (FOS) 
Fructologossacharides (FOS) consist of an organic fructose molecule with β (2-1)-glycosidic 
bonds attached to a d-glucose terminal unit (DOS SANTOS FELSSNER et al., 2016). Among the 
pathways, it is possible that FOS is synthesized by the partial hydrolysis of long-chain inulin through 
the action of endo-inulinases enzymes or by the work of β-fructosidase in the transfructosylation of 
sucrose (CHEN et al., 2020). 
Dogs and cats do not have digestive enzymes capable of digesting certain vegetable fibers. 
Fructooligosaccharides are non-digestible fibers in the small intestine, and their degradation occurs in 
the colon of these animals (SCOTT et al., 2015). Bacteria components of the microbiota of animals is 
responsible for synthesizing short chain fatty acids (SCFA) and lactate, from the fermentation of these 
components in the large intestine. Furthermore, they can be a source of energy for the host, lower the 
intestinal pH and control the multiplication of pathogenic microorganisms (ROBERFROID et al., 
2010). 
 
Galactoigosaccharides (GOS) 
Galactooligosaccharide (GOS) is a prebiotic, produced through enzymatic conversion of 
lactose and consists mainly of galactose and glucose molecules (GOSLING et al. 2010). GOSs are 
usually composed of 2-10 galactose molecules and 1 glucose molecule. They are usually synthesized 
from the transgalactosidase activity of β-galactosidases. Naturally occurring GOSs can be present in 
some plant products (Table 1), mainly in legumes and cereals (FIORI et al., 2022). 
Table 1. Food sources and their compositions of FOS and GOS (g/100g). 
Source FOS kestose (g/100g) GOS raffinose (g/110g) 
Apple 0.009 0.0034 
Banana 0.168 - 
Carrot 0.022 - 
Chicory raw 0.0039 0.0025 
Garlic raw 0.306 - 
Lentils - 0.032 
Orange 0.012 0.011 
Peach 0.015 0.005 
Peas 0.010 0.052 
Source: Adapted from Fiori et al. (2022). 
For more than 70 years, these oligosaccharides have been studied due to their prebiotic and 
bifidogenic potential identified in the microbiota of children breastfed with human milk (MARTINS & 
BURKERT, 2009). After the identification of their biological effects in infant child, 
galactooligosaccharides began to be produced commercially. Its synthesis occurs through the 
transgalactosylation activity of the enzyme β-galactosidase on high concentrations of lactose 
(GOSLING et al., 2010) and its molecular structure was developed based on the human milk 
oligosaccharides (SELA & MILLS, 2010). 
By resisting the metabolic processes of fermentation, GOS serve as an energy source for the 
proliferation of anaerobic bacteria in the colon (ROBERFROID et al., 2010). In particular, they are 
considered bifidogenic, as they serve as a substrate for bifidobacteria and stimulate their cellular 
metabolism and proliferation (ROBERFROID, 2007). Therefore, its prebiotic effect is considered to be 
of high biologic value and recent studies attribute a number of potential health benefits to GOS (FAI et 
al., 2015). Among the beneficial effects, there is this increase in the population of Bifidobacteria in the 
colon and, by antagonistic effect, the suppression of the activity of putrefactive bacteria, which reduces 
the formation of toxic metabolites (NERI et al., 2009; MONTILLA et al., 2015). 
 
Xyloligosaccharides (XOS) 
Xyloligosaccharides (XOS) are oligosaccharides composed of non-caloric, non-digestible 
xylose units, which appear naturally in bamboo shoots, fruits, vegetables, milk, and honey. They are 
high value co-products for biofuel generation from cellulosic biomass. XOSs are present in low 
concentrations in most plants and are produced by hydrolysis of hemicelluloses. Due to hydrolysis of 
sugarcane bagasse, XOSs constitute up to 50.35% of the starting biomass. There is a growing interest 
in the production of XOS due to their ability to stimulate the growth of intestinal microorganisms in 
humans, such as species of the genera Lactobacillus and Bifidobacterium (ZHANG et al., 2021). Its 
industrial-scale production is carried out from lignocellulosic materials (LCMs). The LCMs for XO 
production come from various raw materials (from forestry, agriculture, industry or municipal solid 
waste) that present similarities in composition (VÁZQUEZ et al., 2000). 
In fish, XOS has demonstrated beneficial effects such as increased antioxidant capacity, anti-
inflammatory and antimicrobial functions (ABASUBONG et al., 2018). In humans, 4g/day of XOS for 
8 weeks resulted in reduced glucose, frutosamine, cholesterol and low-density lipoprotein (LDL) in 
patients with diabetes mellitus (SHEU et al., 2008). 
 
Inulin and Oligofructose 
Inulin is present in more than 36,000 plant species. Most commercially available inulin is 
extracted from chicory roots (contains 150 to 200 mg/g inulin and 80 to 120 mg/ g oligofructose). 
Chemically, inulin is a polydisperse β-(2,1) fructan. Oligofructose contains 2 to 8 monosaccharide 
residues connected by glycosidic bonds and can be obtained by partial enzymatic hydrolysis of chicory 
inulin, which contains both β-(2-1) fructose chains and β-(2,1) fructose chains with glucose terminal 
units. Synthesized oligofructose contains only β-(2,1) fructose with glucose end units. These structures 
prevent oligofructose or inulin from being digested in the upper intestinal tract of monogastric animals, 
making them available for fermentation by intestinal bacteria (FLICKINGER et al., 2003). 
Oligofructose, a natural food ingredient, is the product of partial enzymatic hydrolysis of inulin.This non-digestible oligosaccharide is fermented by colonic bacteria to produce mainly short-chain 
fatty acids, L-lactate and CO, and the energy needed for bacterial growth, as well as increasing fecal 
mass. Compared to starch, cellulose, or any dietary fiber, oligosaccharides have only a low (2-20) 
degree of polymerization (DP), and consequently have low molecular weight (up to 3500). Among the 
subproducts, mainly short-chain fatty acids (SCFA) act beneficially in maintaining eubiosis and can 
also act as growth promoters (SUKOR et al., 2016; NG & KOH, 2016). Therefore, some known 
nutritional effects of inulin and FOS are their ability to modify the composition of the intestinal 
microbiome e.g., by stimulating the proliferation of Bifidobacteria, and their metabolic activity in the 
colon (ROBERFROID et al., 1998; VAN LOO et al., 1999). Oligosaccharides are readily soluble in 
water and structurally, are fructose polymers linked by 61-2 osidic bonds, of which one end is 
occupied by either a fructose pD, or a glucose aD. Oligofructose is completely resistant to digestion in 
the upper GI tract and is fermented in the colon, where it serves as substrates for selective growth of 
bifidobacteria (ROBERFROID et al., 2009). 
 
 
 
 
 
 
Table 2. Sources and percentages of inulin and oligofructose in the main foods used in the cat food 
market. 
Source Inulin (%) Oligofructose (%) 
Banana 0.3-0.7 0.3-0.7 
Rye 0.5-1 0.5-1 
Leek 3-10 2.5-8 
Wheat 1-4 1-4 
Garlic 9-16 3.5-6.5 
Chicory roots 15-20 8-11 
Onions 1.1-7.5 1.1-7.5 
Source: Adapted from Roberfroid et al. (2009). 
 
The use of drugs with prebiotics can alter their effect. In rats, the combination of oligofructose 
and ampicillin reduced adiposity, and ampicillin prevented the prebiotic-induced increase in 
bifidobacteria and lactobacilli (BOMHOF et al., 2016). 
 
Prebiotics in cat food 
Prebiotics are widely used in cat foods as modulators in intestinal and immunological 
parameters. However, there are few published studies that have evaluated different prebiotics in cat 
diets. Some studies, use only the fecal inoculum of the animals, due to the practicality of experimental 
design. In the study by Calabrò et al. (2020), they compared the fermentability of six cell walls of 
Saccharomyces cerevisiae obtained through three production processes (alcoholic, brewery, and baker) 
in cat fecal inoculum. As results, the alcoholic substrate demonstrated higher fermentation rate. The 
baker's substrate, on the other hand, showed the lowest fermentation rate, which corresponded to the 
highest production of iso-butyrate and iso-valerate. The brewer's substrate showed the highest 
production of acetate and butyrate, suggesting that the alcoholic and brewer's substrates are more 
suitable for inclusion in the cat diet. 
An in vittro study evaluated the prebiotic potential of three oligosaccharides: FOS, GOS and 
lactosucrose in cat fecal inocula and, demonstrated that lactosucrose porduced 14.0% more gas, 61.0% 
more lactate compared to the other prebiotics. This study suggests that lactosucrose has a positive 
impact on the lactate-producing bacteria in the feline colon (KELLY et al., 2006). 
Some prebiotics may also help reduce stress in cats. A blend containing L-tryptophan, lemon 
balm, fish peptides and oligofructose resulted in a 24-hour reduction in cortisol and urinary creatinine 
in healthy adult cats (JEUSETTE et al., 2021). In obese cats, on the other hand, supplementation of 
2.5% oligofructose and inulin for 4 weeks resulted in higher propionylcarnitine concentrations, 
suggesting fermentation in the colon and propionate absorption. In addition, they observed that 
prebiotic supplementation reduced methylmalonylcarnitine and aspartate aminotransferase 
concentrations, indicating reduced amino acid gluconeogenesis (VERBRUGGHE et al., 2009). Studies 
in cats with inflammatory bowel disease observed no effect on modulation of the gut microbiota with a 
GOS supplementation. However, the study did not evaluate other important parameters for 
comorbidity such as fermentation products and immunological parameters (ABECIA et al., 2010). 
However, do all prebiotics promote positive effects on metabolism in cats? And can the time of 
modulation affect their effects? Or the type and concentration of prebiotic? Given the above, the aim 
of the study was to demonstrate the potential effects of different prebiotics on the diet of healthy cats. 
 
Material and Methods 
 
The articles were searched for by the Embase and Pubmed platforms, based on the keywords 
described in table 1. After the research, the articles were plotted in the Mendeley® program in order to 
exclude duplicates and articles that do not involve the ingestion of prebiotics in healthy cats. The 
results considered by the authors were of p<0.05, and tendencies were not considered as significant. 
 
Table 1. Search terms, databases and number of results found about health studies with prebiotics 
supplementation. 
Database/date 
covered/number of 
results 
Search terms 
Embase 
Data covered: not 
specified, all years 
were searched 
Number of results: 
55.228 
('cat'/exp OR 'cat cat' OR 'cat domesticus' OR 'cats' OR 'felis catus' OR 'felis') AND 
('prebiotic agent'/exp OR 'prebiotic' OR 'prebiotic agent' OR 'prebiotics' OR 'fructose 
oligosaccharide'/exp OR 'fructo oligosaccharide' OR 'fructooligosaccharide' OR 
'fructose oligosaccharide' OR 'neosugar' OR 'oligofructose' OR 
'mannanoligosaccharide'/exp OR 'galactose oligosaccharide'/exp OR 'galacto 
oligosaccharide' OR 'galactooligosaccharide' OR 'galactose oligomer' OR 'galactose 
oligosaccharide' OR 'oligogalactose' OR 'inulin'/exp OR 'alant starch' OR 'alantin' OR 
'alantin starch' OR 'dahlin' OR 'inulin' OR 'inulin and sodium chloride' OR 'inulin t' OR 
'inuline' OR 'synanthrin' OR 'beta glucan'/exp OR 'beta dextroglucan' OR 'beta glucan' 
OR 'beta glucans' OR 'beta-glucans' OR 'macrogard' OR 'polydextrose'/exp OR 
'lactulose'/exp OR 'arabinogalactan'/exp) 
Pubmed 
Data covered: not 
specified, all years 
were searched 
Number of results: 
11.116 
('cat'/exp OR 'cat cat' OR 'cat domesticus' OR 'cats' OR 'felis catus' OR 'felis') AND 
('prebiotic agent'/exp OR 'prebiotic' OR 'prebiotic agent' OR 'prebiotics' OR 'fructose 
oligosaccharide'/exp OR 'fructo oligosaccharide' OR ‘microbiota’ OR 
'fructooligosaccharide' OR 'fructose oligosaccharide' OR 'neosugar' OR 'oligofructose' 
OR 'mannanoligosaccharide'/exp OR 'galactose oligosaccharide'/exp OR 'galacto 
oligosaccharide' OR 'galactooligosaccharide' OR 'galactose oligomer' OR 'galactose 
oligosaccharide' OR 'oligogalactose' OR 'inulin'/exp OR 'alant starch' OR 'alantin' OR 
'alantin starch' OR 'dahlin' OR 'inulin' OR 'inulin and sodium chloride' OR 'inulin t' OR 
'inuline' OR 'synanthrin' OR 'beta glucan'/exp OR 'beta dextroglucan' OR 'beta glucan' 
OR 'beta glucans' OR 'beta-glucans' OR 'macrogard' OR 'polydextrose'/exp OR 
'lactulose'/exp OR 'arabinogalactan'/exp) 
 
 
 
Results 
 
All the articles regarding prebiotics in healthy cats were obtained and then exported to 
Mendeley® citation manager. After duplicates were removed, a total of 2128 remained. The authors 
decided to consider only those with in vivo utilization of prebiotics in healthy cats to conduct a more 
detailed analysis on the subject. After removing articles regarding in vitro use, and studies that used 
medication during prebiotic intake, 14 articles were used for the state-of-the-art analysis (Table 3). The 
results of the articles were discussed afterward. 
Table 3. The state-of-the-art analysis of studies conducted with healthy cats with prebiotic 
supplementation obtained after systematic research. 
1. Terada, A. et al. (1993) 
Population: Healthy adult cats 
Sample size: Eight cats 
Intervention details: Each animal received a control treatment + 175 mg of 
lactosucrose perday for 2 weeks. 
Study design: Completely Randomized Design. 
Outcome studied: To determine the effects of lactosucrose on the flora, fecal 
concentrations of putrefactive products, pH, and water content 
of cats, wich are related to the offensive odor of feces. 
Main findings: 
(relevant to PICO question): 
During lactosucrose administration, the lactobacilli increased, 
whereas Clostridium perfringens and Enterobacteriaceace 
decreased. The fusobacteria and staphylococci were decreased 
on day 7 of supplementation, while bacteroides were increased 
on day 14. Bifidobacteria increased during lactosucrose 
supplementation, while Spirochaetaceae and lecithinase-
negative clostridia decreased on day 14 of supplementation. 
Fecal concentrations of ammonia, índole, ethylphenol, and 
urinary ammonia were reduced on day 14 of supplementation. 
The water contente, pH and weight of the feces increased 
during lactosucrose administration. The environmental 
ammonia and the fecal odor also decreased. 
Limitations: The study wasn’t limitations. 
2. Sparkes, A.H. et al. (1998a) 
Population: Healthy adult cats 
Sample size: Twelve cats 
Intervention details: The animals were fed a basal diet and a diet with 0.75% FOS. 
Duodenal juice for bacteriological examination was collected 
via oral endoscopy 5 times from each cat over a period of 32 
weeks. Duration of study: 32 weeks. 
Study design: Completely Randomized Design. 
Outcome studied: To investigate changes in the duodenal microbiota of healthy 
cats over time and to evaluate the effect of dietary 
supplementation with FOS. 
Main findings: 
(relevant to PICO question): 
The mean aerobic, anaerobic, and total bacterial counts did not 
differ significantly between sample collection times. However, 
the individual counts for each animal showed considerable 
variations. The bacterial flora varied qualitatively: only 
Enterococcus faecalis, Clostridium perfringens, Bacteroides, 
Pasteurella, and Streptococcus spp, and unidentified gram-
negative (aerobic) rods were present in > 50.0% of the samples. 
Limitations: The study wasn’t limitations. 
3. Sparkes, A.H. et al. (1998b) 
Population: Healthy adult cats 
Sample size: Twelve cats 
Intervention details: The animals first received a basal diet for 8 weeks. Afterwards, 
they received a diet supplemented with 0.75% FOS. 
Study design: Completely Randomized Design. 
Outcome studied: Investigate changes in the fecal flora of healthy cats after 
dietary supplementation with FOS. 
Main findings: 
(relevant to PICO question): 
Members of the genus Bacteroides, Clostridium perfringens, 
Escherichia coli, lactobacilli, and Plesiomonas shigeloides were 
the most prevalent bacteria isolated. Compared with samples 
from cats fed a control diet, there was an increase in the mean 
count of lactobacilli (P = 0.02) and Bacteroides spp (P = 0.05) 
after FOS supplementation, and reduced mean numbers of 
Escherichia coli. 
Limitations: The study wasn’t limitations. 
4. Hesta, M. et al. (2001) 
Population: Healthy adult cats 
Sample size: Eight cats 
Intervention details: Four treatments were used in first experiment: 0, 3.0%, 6.0% 
and 9.0% of oligofructoseof DM. The second experiment was 
used three inulin diets: 0%, 3.0% and 6.0% and one 
oligofructose (3.0%). The duration of study was 160 days (48 
days in first experiment and 112 days in the second 
experiment). The diet was supplemented with the different 
amounts of oligofructose or inulin and mixed thoroughly. 
Study design: Latin square design. 
Outcome studied: In the first experiment, different concentrations of oligofructose 
were tested for their impact on faecal characteristics. The aim of 
the second experiment was to examine the effects of inulin and 
oligofructose on digestibility parameters and faecal bacterial 
nitrogen in healthy cats. 
Main findings: 
(relevant to PICO question): 
In the first experimente there was no significant differences 
regarding the macroscopical and chemical aspects of the faeces 
between the control and the 3.0% supplemented group. The 
amount of fresh faeces produced per day were higher in the 
9.0% supplemented FOS group compared with the control or 
the 3.0% FOS group. In the 9% FOS group the faeces was 
formless and the code (fecal score) for consistency was lowest. 
In the 6.0% FOS group the code for consistency was also 
signi®cantly lower than the 3.0% FOS group and the control. 
There was a trend for a lower pH of the faeces in the 3% 
supplemented group. In a second experiment, the supplemented 
groups the apparent protein digestibility was lower but this was 
due to a higher bacterial nitrogen content of the faeces. There 
were no significant differences between 3.0% inulin and 
oligofructose. Urine production was lower in all supplemented 
groups. The total amount of SCFA excreted was increased in 
the 6% inulin group compared with the control group. In the 
6% inulin group decreased acetic acid and increased valeric 
acid compared from the control. The 6.0% inulin group 
increased excretion of propionic and butyric acid. 
Limitations: The study wasn’t limitations. 
5. Hesta, M. et al. (2005) 
Population: Healthy adult cats 
Sample size: Four cats 
Intervention details: Two treatments were used: control diet and 3.11% of FOS on 
DM. The duration of study was 26 days. The prebiotic was 
included in the mass of the food. 
Study design: Crossover study 
Outcome studied: To evaluate the addition of oligofructose on urea metabolism in 
cats by the use of 15N-labelled urea and on faecal odour 
components. 
Main findings: 
(relevant to PICO question): 
There were no significant differences between the injected 
amounts of labelled 15N and the excreted amount of 15N in 
urine and faeces after subtraction of the basal faecal and urinary 
15N excretion. Twenty-seven different S-containing odour 
components were detected in the incubated fresh faecal 
samples. Only 11 odour components could be identified. There 
was no difference between the control and the FOS group for 
parameters. The authors observed tendences. 
Limitations: The study wasn’t limitations. 
6. Aquino, A.A. et al. (2010) 
Population: Healthy adult cats 
Sample size: Twenty cats 
Intervention details: Four diets were used: wet commercial diet (control) and control 
plus 0.2, 0.4, or 0.6% of YCW in dry matter. The duration of 
study was 30 days. The additive was incorporated into the 
comercial diet. 
Study design: Completely Randomized Design. 
Outcome studied: To evaluate the effect of increasing levels of YCW, 0%, 0.2%, 
0.4% and 0.6%, in the dry matter of the diet for adult cats on the 
nutrient and energy digestibility of nutrients and energy in 
commercial wet and dry diets, as well as the effect of including 
0.4% YCW on the palatability of wet and dry wet diet. 
Main findings: 
(relevant to PICO question): 
No differences among treatments for dry matter, crude protein, 
ether extract, organic matter, gross energy digestibility, and 
faecal score were observed. Positive linear effect on dry matter 
digestibility was observed. Negative effect of 0.4% YCW 
inclusion on palatability of diet was observed. 
Limitations: The study wasn’t limitations. 
7. Barry, K. A. et al. (2010) 
Population: Healthy young adult cats 
Sample size: Twelve domestic shorthair males 
Intervention details: Three diets were used: 4.0% of cellulose/kg, 4.0% of 
fructooligosaccharides (FOS)/kg and 4.0% of pectin/kg. The 
duration of study was 90 days. Cellulose, FOS, or pectin was 
incorporated into the diets. 
Study design: 3 x 3 latin square design 
Outcome studied: To determine nutrient digestibility, fecal protein catabolite 
concentrations, and fecal microbiota concentrations in adult cats 
fed diets containing fiber sources selected for differences in 
fermentability, solubility, and prebiotic potential. 
Main findings: 
(relevantto PICO question): 
No differences were observed in intake of DM, OM, CP, or 
acid-hydrolyzed fat; DM or OM digestibility; or fecal pH, 
DM%, output on an as-is or DM basis, or concentrations of 
histamine or phenylalanine. Crude protein and fat digestibility 
decreased in response to supplementation with pectin compared 
with cellulose. FOS and pectin supplementation resulted in 
increased fecal scores and concentrations of ammonia and 4-
methyl phenol. Fecal indole concentrations increased when cats 
were supplemented with FOS. Fecal acetate, propionate, and 
total short-chain fatty acid concentrations increased in pectin-
supplemented cats. Fecal butyrate, isobutyrate, isovalerate, 
valerate, and total branched-chain fatty acids + valerate 
concentrations increased with supplementation of FOS and 
pectin. Fecal cadaverine and tryptamine concentrations 
increased with supplementation of FOS and pectin. Fecal 
tyramine concentrations decreased in FOS supplemented cats, 
whereas spermidine concentrations increased in pectin-
supplemented cats. Fecal concentrations of putrescine and total 
biogenic amines increased with FOS and pectin, the 
concentrations of these compounds were increased in cats 
supplemented with pectin. Fecal Bifidobacterium spp. 
concentrations increased and Escherichia coli concentrations 
decreased in FOS-supplemented cats. 
Limitations: Two cats were removed from the pectin treatment due to poor 
dietary intake. As a result, 10 cats compared with 12 for the 
other treatments were used for the pectin treatment mean 
calculations. 
8. Kanakupt, K. et al. (2011) 
Population: Healthy adult cats 
Sample size: Eight domestic shorthair cats 
Intervention details: Four treatments were used: control diet without prebiotic, 0.5% 
short-chain fructooligosaccharides (scFOS), 0.5% GOS or 0.5% 
scFOS plus 0.5% GOS in DM. The duration of study was 84 
days. The prebiotics were included in the diet before extrusion. 
Study design: Replicated 4 x 4 latin square design 
Outcome studied: To determine the effects of low level prebiotic inclusion [0.5% 
scFOS, 0.5% galactooligosaccharides (GOS), and 0.5% scFOS 
+ 0.5% GOS] on nutrient digestibility, fermentative metabolite 
concentrations, and large bowel microbial ecology of healthy 
adult cats. 
Main findings: 
(relevant to PICO question): 
Apparent total tract CP digestibility was decreased when cats 
were fed a diet containing scFOS + GOS compared with the 
other treatments. Dry matter, OM, acid hydrolyzed fat, and GE 
digestibilities were not different among treatments. Cats fed 
scFOS-, GOS- , and scFOS + GOS-supplemented diets 
increased fecal Bifidobacterium spp. populations compared 
with cats fed the control diet. Fecal pH decreased for cats fed 
the scFOS + GOS-supplemented diet compared with the 
control. Butyrate and valerate concentrations increased when 
cats consumed the scFOS + GOS diet. 
Limitations: The study wasn’t limitation. 
9. Barry, K. A. et al. (2014) 
Population: Healthy senior cats 
Sample size: Eighteen cats 
Intervention details: Three dietary treatments were utilized in this study: a control 
treatment that consisted of a commercially available canned cat 
diet without supplemental fructan (control), a control diet with 
1.0% oligofructose added on a dry weight basis (OF) and a 
control diet with 1.0% of na experimental chicory fructan 
(OF+IN). The duration of study was 28 days. 
Study design: Completely Randomized Design. 
Outcome studied: To determine the effects of supplementing senior cats with two 
prebiotic fructans on N partitioning, nutrient digestibility, fecal 
odor components, and fecal microbiota concentrations 
Main findings: 
(relevant to PICO question): 
The OF+IN supplement decreased fecal indole (P < 0.05), 
tyramine (P < 0.05), and Escherichia coli (P < 0.05) 
concentrations. Both fructan supplement treatments decreased 
(P < 0.05) fecal histamine concentrations. 
Limitations: The study wasn’t limitation. 
Garcia-Mazcorro, J. F. et al. (2017) 
Population: Healthy adul cats 
Sample size: Twelve cats 
Intervention details: The owners offered orally 225 mg of FOS and inulin once per 
day for 16 days. Fecal samples were collected at two time 
points before n (8 days and 1 day before initiation of prebiotic 
administration) and at two time points during prebiotic 
administration (days 8 and 16). 
Study design: Questionare and Completely Randomized Design. 
Outcome studied: To evaluated the effect of a commercially available 
nutraceutical containing fructo-oligosaccharides (FOS) and 
inulin on the fecal microbiota of healthy cats and dogs when 
administered for 16 days. 
Main findings: 
(relevant to PICO question): 
Prebiotic administration was associated with a good acceptance 
and no side effects were reported by the owners. The fecal 
microbiota of cats was dominated by Firmicutes followed by 
smaller proportions of Bacteroidetes. cat number 2 (C2) and cat 
number 5 (C5) showed high increases in the relative abundance 
of Lactobacillales during prebiotic administration. 
Veillonellaceae (order Clostridiales within Firmicutes) was 
significantly increased during prebiotic administration, and also 
that an unknown member of Gammaproteobacteria was 
decreased during prebiotic administration. 
Limitations: One cat had lose or pulpy feces throughout the whole study 
period (i.e., before and during prebiotic) and two cats refused to 
consume the product and were therefore excluded from the 
study. 
Santos, J. P. et al. (2018) 
Population: Healthy adult cats 
Sample size: Fourteen cats 
Intervention details: Four treatments were used: control (0% YCW), 0.2% YCW, 
0.4% YCW and 0.6% YCW. The duration of study was 94 
days. The inclusion of the prebiotic was in the dough. 
Study design: Randomized block design 
Outcome studied: To evaluated the effects of increasing concentrations of spray-
dried yeast cell wall (YCW) in diets for healthy adult cats on 
apparent nutrient digestibility and on bacterial composition and 
fermentation products in the stool. 
Main findings: 
(relevant to PICO question): 
YCW did not affect body weight, nutrient and food intake, 
faecal production, faecal score, faecal pH or urine output. 
Observed a linear reduction in Clostridium perfringens, a 
quadratic reduction in Escherichia coli, and linear increases in 
Bifidobacterium spp. and Lactobacillus spp. with the inclusion 
of YCW. Butyrate, valerate, total biogenic amines, putrescine, 
cadaverine and histamine increased linearly with the inclusion 
of YCW. 
Limitations: The study wasn’t limitations. 
Lyu, Y. et al. (2020) 
Population: Healthy cats 
Sample size: Twenty-four domestic shorthair 
Intervention details: Three dietas were used: Control without xylooligosaccharides 
(XOS) with 1.0% cellulose/kg, 0.04% XOS and 0.96% 
celulose/kg (LXOS) and 0.40% XOS and 0.60% celulose/kg 
(HXOS). All cats were initially adapted to the control diet (1% 
cellulose) for three week. The duration of study was 4 weeks. 
Study design: Completely Randomized Design 
Outcome studied: To evaluate the effects of two XOS supplementation levels in 
cats 
Main findings: 
(relevant to PICO question): 
XOS groups increased blood 3-hydroxybutyryl carnitine levels 
and decreased hexadecanedioyl carnitine levels. XOS 
treatments displayed an increased bacterial abundance of 
Blautia, Clostridium XI, and Collinsella and a decreased 
abundance of Megasphaera and Bifidobacterium. LXOS groups 
increased fecal pH and bacterial abundance of Streptococcus 
and Lactobacillus, decreased blood glutaryl carnitine 
concentration, and Catenibacterium abundance. HXOS group 
showed a more distinct microbiome profile and higher species 
richness, and an increased bacterial abundance of 
Subdoligranulum, Ruminococcaceae genus (unassigned genus), 
Erysipelotrichaceae genus, and Lachnospiraceae. 
Limitations: The studywasn’t limitations. 
Shinohara, M. et al. (2020) 
Population: Healthy cats 
Sample size: Six adult cats 
Intervention details: The cats were administrated 1g/day of 1-kestose for 8 weeks 
followed by a 2-week wash-out period. 
Study design: Completely Randomized Design 
Outcome studied: To investigated the influence of 1-kestose on the feline 
intestinal microbiota. 
Main findings: 
(relevant to PICO question): 
The results suggested that the intestinal bacterial community 
structure in feline assigned to this study was divided into 2 
types: one group mainly composed of the genus Lactobacillus 
(GA) and the other mainly composed of the genus Blautia with 
very few bacteria of Lactobacillus (GB). Furthermore, the 
number of Bifidobacterium slightly increased after the 
administration of 1-kestose (at 4 and 8 weeks) (P<0.1). The 
administration of 1-kestose also increased the abundance of 
Megasphaera, the butyric acid-producing bacteria, at 4 and 8 
weeks (P<0.1). Furthermore, an increase in butyric acid levels 
was observed after the administration of 1-kestose for 4 weeks 
(P<0.1). 
Limitations: The study wasn’t limitations. 
Matheus, L. et al. (2021) 
Population: Healthy cats 
Sample size: Twenty-fouseven cats 
Intervention details: Three diets were used: CD (control diet without YAM), YAM 
0.3 (control diet with 0.3% YAM) and YAM 0.6 (control diet 
with 0.6% YAM). The duration of study was 37 days. 
Study design: Block Design. 
Outcome studied: To evaluate the effects of increasing dosages of a comercial 
product composed by Saccharomyces cerevisiae yeast (YAM). 
Main findings: 
(relevant to PICO question): 
The additive increased the apparent digestibility of crude fber 
and ash (YAM 0.6) without interfering feed consumption, fecal 
production and fecal characteristics. In the treatment YAM 0.3 
increased lactic acid concentration while reducing isovaleric 
acid. No diferences were noticed on biogenic amines (BA), 
fecal pH, ammonia concentration, total and individuals short-
chain fatty acids (SCFA) and total and individuals branched-
chain fatty acids (BCFA). As regards to fecal microbiota, 
prebiotic inclusion has resulted in the reduction of Clostridium 
perfringens. No diferences were found in the immunological 
parameters evaluated. 
Limitations: The study wasn’t limitations. 
 
Discussion 
Studies that used prebiotics and did not demonstrate their effects were not considered. 
According to Table 4, most of the studies included prebiotics in the diet of healthy cats, aiming to 
demonstrate its gastrointestinal effects as well as the modulation of the immune system and intestinal 
microbiota. The main difference between studies is in type and concentration of prebiotic used. 
According to the methodology used, 14 studies were found that used prebiotics in the feeding 
of healthy cats. Of these studies, the prebiotic most often used was FOS, for an average experimental 
duration of 82 days. It is known that the time of inclusion of prebiotics can influence their effects 
(PERINI et al., 2020; SHINOHARA et al., 2020), so the duration of the experiment should be studied 
in advance to avoid the absence of effects. According to Table 4, FOS can assist in gastrointestinal 
metabolism. Also according to the table, fecal pH was within the ideal range of 6.2 to 6.8 (ALLEN & 
KRUGER, 2000) and fecal score was between 2.5 to 2.8, a range 0.3 above the ideal score (Moxham, 
2001). These data demonstrate that this type of prebiotic can improve fecal quality in animals with 
chronic gastrointestinal disorders such as diarrhea, gastroenteritis, and others. In addition, increasing 
the concentrations of short chain fatty acids (acetate, propionate, and butyrate) may assist in the 
absorption of fluids, calcium, magnesium, and other cations in the colon (TOPPING, 1996). Cats fed 
fermentable fiber showed a reduced acetate:propionate ratio compared to animals fed without 
fermentable fiber. This rate and change in SCFA concentrations may demonstrate a change in the 
composition of the gut microbiota (SUNVOLD et al., 1995). In addition, the source of fermentable 
fiber can alter SCFA production, since each fiber has a type of fermentable substrate and a type of 
fermentation, which leads to the proliferation of different bacteria that can produce different fecal 
fermentative products (EHLE et al., 1982). A study using cat fecal inoculum showed that SCFA 
production with FOS was high compared to other fibrous substrates (peanut shells, soybean hulls, 
psyllium gum, citrus fruits, sugar cane pulp and residue) (SUNVOLD et al., 1995). Another in vittro 
study has shown that SCFA production stimulates longitudinal contractions of colonic smooth muscle 
in kittens and adult cats and these involve activation of calcium influx (RONDEAU et al., 2003). 
Acetate, propionate and butyrate represent the majority of the SCFA produced in the feline 
colon and are found in individual concentrations up to 150 mM (BROSEY et al., 2000). SCFA are 
readily absorbed and rapidly metabolized by colonicepithelial cells (BERGMAN, 1990). They 
promote colonocyte differentiation and proliferation (LEDUC et al., 1994), stimulate sodium and 
water reabsorption (HERSCHEL et al., 1981) and inhibit the growth of pathogenic bacteria (IZAT et 
al., 1990). Butyrate is an energy source for the colonocytes, and higher concentrations of this variable 
are thought to be important in intestinal health and colonocyte proliferation (BLOTTIÉRE et al., 
2003). In other words, if FOS is one of the fibers that increases SCFA concentrations, we can report its 
importance in cat food. 
In humans, a study showed that both FOS and GOS (16g/day) reduced the concentrations of 
butyrate in feces after a short intake period of 14 days, in addition to an increase in the relative 
abundance of Bifidobacterium in both the FOS and GOS groups, while butyrate-producing bacteria 
such as Phascolarctobacterium in the FOS group and Ruminococcus in the GOS group were reduced 
(LIU et al., 2017). However, already in cats, FOS increased the concentration of butyrate and 
propionate according to Barry et al. (2010) and Kanakupt et al. (2011). 
Another in vittro study evaluated 6 non-digestible oligosaccharides (gluconic acid, carrot fiber, 
FOS, GOS, lactitol, and citrus fruit pectins) in cat feces and demonstrated that after 24 hours, all 
treatments reduced pH, but putrescine concentrations in the FOS, GOS, and lactitol treatments were 
higher compared to the control diet (PINNA et al., 2014). In addition to FOS, one of its structural 
components, 1-kestose, has shown beneficial effects in cat food, which promoted increased 
proliferation of lactobacilli, bifidobacteria and megasphaera, lactic acid-producing bacteria, and 
increased concentrations of butyric acid (SHINOHARA et al., 2020).
 
Table 4. Means and standard error of the effects of FOS on fecal variables and consumption in cats. 
Reference FOS 
concentration 
Feed 
intake 
(g/day) 
Fecal 
output (g/ 
as-is basis) 
Fecal DM 
(%) 
Fecal 
score 
Fecal 
pH 
Ammonia 
(µmol/g of 
DM) 
Acetate 
(µmol/g of 
DM) 
Propionate 
(µmol/g of DM) 
Butyrate (µmol/g of 
DM) 
Hesta et al. 
(2005) 
3.11% of DM 146.5 3.95* 79.0 2.68 - -- - - - 
Barry et al. 
(2010) 
4.0% 68.7 30.1 34.0 2.8 6.4 0.2 217.9 61.1 97.3 
Kanakupt et 
al. 2011 
0.5% 58.3 168.0 44.4 2.7 6.4 125.7 173.8 53.1 31.4 
*g DM/day; DM: dry matter.
 
During colonic fermentation of endogenous and undigested amino acids, several putrefactive 
compounds are produced that are responsible for the foul odor of feces. These compounds include 
ammonia, aliphatic amines (agmatine, cadaverine, phenylethylamine, putrescine, and tyramine), 
branched-chain fatty acids (isobutyrate and isovalinate), indoles (indole, 3-methylindole [skatole], 2-
methylindole, 2,3-methylindole, and 2,5-methylindole), phenols (phenol, p-cresol, and 4-ethylphenol),and with volatile sulfur (dimethyl disulfide, diethyl disulfide, di-n-propyl disulfide, and di-n-butyl). 
These compounds are produced from amino acids by deamination (ammonia), deamination-
decarboxylation (short-chain fatty acids), or decarboxylation processes (aliphatic amines). Many of 
these putrefactive compounds have adverse colon health effect processes. Santos et al. (2018) 
demonstrated that inclusion of YCW increased putrescine and cadaverine concentrations. However, 
Barry et al. (2014) demonstrated that the inclusion of 1.0% oligofructose in cat feed reduced the 
concentrations of indole and histamine, putrefactive substances. Barry et a. (2010), on the other hand, 
reported that the inclusion of 4.0% FOS and pectin increased the concentrations of indole, isobutyrate, 
isovalerate, valerate, and cadaverine. In other words, depending on the concentration and type of 
prebiotic used in cat food, the concentrations of putrefactive compounds may change, which may 
interfere with intestinal health. 
The organisms that make up the gut microbiota have an important influence on mammalian 
health, modulating the immune system and providing resistance to pathogens. Oba et al. (2020) 
demonstrated in their study that milk oligosaccharides (GNU100) in cat fecal inocula increased GCFA, 
with acetate being the highest proportion, increased lactate and ammonia. In addition, they observed 
that these oligosaccharides reduced populations of Escherichia/Shigella and Salmonella and, increased 
populations of Bifidobacteria and Lactobacilli, beneficial bacteria in the feline gut microbiota 
(GARCIA-MAZCORRO et al., 2017). Oba et al. (2021), meanwhile, demonstrated that 1.5% GNU100 
in the diet of 32 cats increased butyrate concentration and reduced indole, and reduced Campylobacter 
populations. The authors stated that this oligosaccharide can be used in cat foods safely and suggest 
potential benefits on gastrointestinal health. Terada et al. (1993) reported in dog and cat fed 
lactosucrose increased bifidobacteria while decreasing pathogenic organisms such as C. perfringens. 
Bifidobacteria constitute up to 25.0% of the saccharolytic bacteria in the total bacterial population in 
the gut of adult humans and animals, and their positive biological activities have received much 
attention (HUSSEIN et al., 1999). In other words, most of the different prebiotics positively modulate 
the gut microbiota in healthy cats, which intensifies and encourages their use in animals with 
gastrointestinal disorders (GUARINO et al., 2020). 
Cats require higher concentrations of dietary protein in part to meet their unique amino acid 
requirements. This leads to an active population of clostridial species throughout the GI tract that are 
the primary species that utilize amino acids as fermentative substrates. Consequently, various 
putrefactive compounds, including ammonia, biogenic amines, branched-chain fatty acids (BCFA), 
indole, and phenol, can be produced (KANAKUPT et al., 2011). The composition of the diet, such as 
protein content, can influence the effects of prebiotics on the gut microbiota in cats. According to 
Pinna et al. (2014) it was found that the higher the protein the greater the negative effect on the gut 
microbiota of cats, as high protein concentrations increased Clostridium perfringens populations and 
reduced Lactobacillus spp. Lubbs et al. (2009) observed that a diet with about 52.88% protein reduced 
bifidobacteria compared to a diet with 32.0% protein and that, Clostridium perfringens populations 
were higher in the high protein treatment. Clostridium perfringens contributes to the production of 
various toxins and in the causes of intestinal diseases such as enteritis (ALLAART et al., 2013). 
However, when carbohydrates are limited, BCFA are produced, compounds that are considered 
putrefactive and harmful to the host's health. According to the studies noted above, prebiotics have a 
potential benefit of reducing these BCFA in cats, which may prevent the development of metabolic 
changes (KANAKUPT et al., 2011). 
In order to use the best prebiotic, studies have shown the importance of knowing the 
fermentation characteristics of these substrates before their use in diet formulation, in order to obtain 
the best effects (CALABRÒ et al., 2020). Besides fermentation, the type of prebiotic (BARRY et al., 
2014), the inclusion of prebiotic (AQUINO et al., 2010), the process of inclusion in the feed, and the 
time (PERINI et al., 2020, TERADA et al., 1993) of use of these substrates should be taken into 
consideration in the experimental design, due to the modulation of effects according to these 
parameters. Terada et al. (1993) demonstrated positive effects when administering 175 mg of 
lactosucrose to 8 cats for 14 days. Lyu et al. (2020) and Matheus et al. (2021), on the other hand, 
evaluated the positive effects of XOS, cellulose, and Saccharomyces cerevisiae yeast for 4 weeks. 
One of the most important effects of prebiotics on animals is the modulation of the gut 
microbiota. This modulation can be affected by diet type (BUTOWSKI et al., 2021), guardian (DU et 
al., 2021), ingredients (DE GODOY et al., 2013), age (BERMINGHAM et al., 2018), breed and 
environment (OLDER et al., 2019), diseases (MONDO et al., 2019), and temperature (TAL et al., 
2017). Most studies listed in Table 3 reported that all prebiotics used in cat diets increased 
bifidobacteria and lactobacilli populations and reduced Clostridium perfringens and Eschericia coli 
(TERADA et al., 1993; SPARKER et al., 1998a;1998b; BARRY et al., 2010; BARRY et al., 2014; 
GARCIA-MAZCORRO et al., 2017; SANTOS et al., 2018; MATHEUS et al., 2021). Bifidobacteria 
and lactobacilli are microorganisms beneficial to the host as they ferment carbohydrates, which results 
in the production of butyrate. Another metabolite derived from these bacteria is GABA and its 
precursor gamma-hydroxybutyric acid (GHB) (PILLA & SUCHODOLSKI, 2021). Other research has 
suggested that enterococci, rather than the traditional bifidobacterium and lactobacilli species, may be 
important components of feline gut health due to their production of lactic acid (MASUOKA et al., 
2017). 
Bacteria can be biomarkers for changes such as dysbiosis, which is caused by the reduction of 
enteric bacteria, staphylococci, streptococci, pseudomonas, cytrobacteria, and enterobacteria 
(BUGROV et al., 2022). In humans, the reduction of Faecalibacterium prausnitzii in inflammatory 
bowel disease (IBD) was found to be a determining factor to be considered a biomarker (SOKOL et 
al., 2009). In other words, the determination of bacteria in the inclusion of prebiotics is crucial for the 
development of a possible biomarker for this functional additive. 
According to Bergmingham et al. (2018), unclassified members of bacteroidetes, bacteroidales, 
and bacteroidaceae were associated with isovalerate and isobutyrate concentrations, total food intake, 
fecal gross energy concentrations, and metabolizable energy content of the diet. A reduction in C. 
perfringens may imply a reduction in butyrate concentrations, since this bacterium produces it (PILLA 
& SUCHODOLSKI, 2021), data that corroborate with Kanakupt et al. (2011). C. perfringens is a 
normal commensal of the feline gut, with reported isolation rates of up to 63.0% from healthy cats. 
This bacterium is a gram-positive anaerobic bacillus, a common inhabitant of the intestinal tract, and 
an important pathogen responsible for a broad spectrum of human and veterinary diseases. The main 
virulence factor associated with C. perfringens-associated diarrhea is an enterotoxin (CPE Clostridium 
perfringens enterotoxin) encoded by the cpe gene. CPE induces its toxicity by interacting with 
intestinal tight junctions, affecting transmembrane pores and leading to changes in epithelial 
permeability (MINAMOTO et al., 2012). In other words, modulation ofthe gut microbiota by 
prebiotics is beneficial to the host. 
No studies have been found demonstrating the inclusion of b-glucans in the diet of healthy cats. 
However, this prebiotic is known to contribute to the immune system in humans (NIEMAN et al., 
2008) and animals (KIM et al., 2009; MALEWSKA et al., 2011). One study demonstrated that 0.5% 
betaine, 0.58% oat beta glucan and 0.40% short chain fructooligosaccharides (scFOS) reduced uremic 
phenolic toxin concentrations (HALL et al., 2020). In a case report, a senior cat with a fully exposed 
(no skin and hair) and necrotic left anterior paw was treated with oral administration of 2 ml of beta 
glucan and application of gel composed of beta glucan, chlorhexidine digluconate, and pure bee honey 
to the wound once daily. After 10 weeks of treatment, the animal showed significant improvement, 
which its paw already showed advanced healing and a deposition of hair (MICHÁĽOVÁ & 
FIALKOVIČOVÁ, 2019). Already in a study in dogs, oral administration of 150 mg of beta glucan for 
4 weeks reduced the total immunoglobulin A level and increased immunoglobulin M (STUYVEN et 
al., 2010). Despite being an unexplored prebiotic in healthy animals, beta glucans have important 
functionality in the healing and immune system of cats. 
 
Conclusion 
After carefully reviewing all data included in the present study, it can be concluded that 
prebiotics are beneficial components to healthy adult cats. As the effects of prebiotics differ according 
to source, concentration, and length of the supplementation period, more research is necessary to 
evaluate their short and long-term effects on gut microbiota and health in general. Moreover, the 
prebiotics revised in this review were considered potential prebiotics for cats because their effects 
improving intestinal health and altered intestinal microbiota, which influences the cat's health. 
 
 
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