The feline gut microbiota consists of a diverse and dynamic community of microorganisms residing in the intestinal tract of cats. This complex ecosystem plays a crucial role in digestion, nutrient absorption, immune regulation, and the maintenance of overall health (Alessandri et al., 2020a).
Core composition and diversity
The predominant bacterial phyla in the feline gut include Bacillota, Bacteroidota, Pseudomonadota, Actinomycetota, and Fusobacteriota. Common genera are Anaerococcus, Fusobacterium, Bacteroides, Escherichia-Shigella, Lactobacillus, and Prevotella. These taxa contribute to essential functions such as fermentation of dietary fibers, production of short-chain fatty acids (SCFAs), and pathogen resistance (Alessandri et al., 2020a; Alessandri et al., 2020b; Li et al., 2022; Meazzi et al., 2019).
Breed-specific differences in gut microbiota have been observed. Compared to pedigree Ragdoll cats, non-pedigree domestic cats exhibit higher overall microbial diversity and richness. In contrast, Ragdoll cats show a higher relative abundance of beneficial genera such as Lactobacillus and Enterococcus, which are associated with gut health and immune function (Li et al., 2022).
At the genus level, the core microbiota of cats and dogs is similar, but species-level differences (particularly among bifidobacteria) highlight host-specific adaptations. For instance, feline-associated Bifidobacterium species differ genetically and functionally from those found in canines, suggesting evolutionary divergence in gut symbiosis (Alessandri et al., 2020b).
Influencing factors
- Diet plays a pivotal role in shaping the feline gut microbiome. High-protein, low-carbohydrate diets, typical of obligate carnivores, can increase the diversity of antibiotic resistance genes (ARGs) and alter microbial composition and function (Kim et al., 2020). These dietary patterns may also influence the metabolic output of the microbiota, including SCFA profiles and bile acid metabolism.
- Genetics and breed influence microbial community structure. Distinct microbial signatures have been linked to breed-specific traits, suggesting that host genetics may modulate microbial colonization and stability (Li et al., 2022).
- Infections, such as Toxocara cati and feline coronavirus (FCoV), can subtly shift microbial composition. While overall diversity may remain stable, specific taxa may increase or decrease in response to parasitic or viral presence, potentially affecting immune responses and gut barrier integrity (Duarte et al., 2016; Meazzi et al., 2019).
- Chronic diseases, including obesity, inflammatory bowel disease (IBD), and low-grade intestinal T-cell lymphoma, are associated with reduced microbial diversity and dysbiosis. These conditions often involve a decrease in beneficial bacteria and an increase in pro-inflammatory or opportunistic taxa (Drut et al., 2024; Ma et al., 2022).
Health implications and interventions
In obese cats, gut microbiota shows reduced diversity, lower Bacillota abundance, and altered ratios of key bacterial groups. Specific microbial shifts—such as enrichment of Bacteroides and depletion of Lactobacillus—may serve as biomarkers for obesity and targets for therapeutic intervention (Ma et al., 2022).
Beyond obesity, gut microbiota alterations are increasingly associated with gastrointestinal diseases such as IBD, lymphoma, and infections. These changes can influence immune responses, disease progression, and treatment outcomes, highlighting the potential for microbiome-based diagnostics and therapies in feline medicine (Drut et al., 2024; Meazzi et al., 2019).
Against this backdrop, probiotic supplementation has emerged as a promising approach to support gut health. Multistrain formulations, including Saccharomyces boulardii and Pediococcus acidilactici, have been linked to increased short-chain fatty acid (SCFA) production, reduced intestinal inflammation, improved antioxidant status, and the promotion of beneficial microbial populations, all while maintaining overall microbial diversity (Li et al., 2023).
However, despite these promising outcomes, the current body of research is limited by a significant reliance on probiotic strains originally isolated from humans. As a result, the specific physiological responses and long-term health benefits in feline hosts remain insufficiently characterized. Most studies do not account for the unique features of the feline gut microbiome, and there is a notable gap in evidence regarding the safety, colonization efficiency, and functional impact of probiotics in cats. This underscores an urgent need for targeted research using pet-derived strains to better assess their efficacy, optimize formulations, and establish clinical guidelines for probiotic use in feline health (Lee et al., 2022; Li et al., 2023).
To support such research, in vitro fermentation models have become valuable tools for simulating the feline gut environment. These models allow controlled investigations into dietary and pharmaceutical interventions, paving the way for more precise strategies to improve gut health (Ren et al., 2025).
REFERENCES
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