Multi-Omics Analyses of the Gut Microbiota and Metabolism in Cats with Different Body Conditions and the Effects of Fecal Microbiota Transplantation

Obesity is increasingly recognized in domestic cats and is associated with metabolic disturbances such as insulin resistance and dyslipidemia. The gut microbiota is considered an important regulator of host metabolism, yet its role in feline obesity remains unclear. In this study, a multi-omics approach was used to investigate gut microbiota composition and metabolic profiles in cats with different body conditions and to evaluate the effects of fecal microbiota transplantation (FMT) on the feline gut microbiota and overall metabolism. In Experiment 1, twenty-four cats were classified as obese, normal, or lean, and their gut microbiota and serum metabolites were analyzed. In Experiment 2, fecal microbiota from obese or lean donors were transplanted into recipient cats. Although overall microbial diversity and community structure did not differ significantly among groups, Coriobacteriaceae and Collinsella were enriched in obese cats, whereas Enterobacteriaceae-related taxa were more abundant in normal-weight cats. Serum metabolomics revealed alterations mainly related to amino acid and antioxidant metabolism, including O-acetylcarnitine, glutathione, and tryptophan metabolism. FMT shifted the recipient gut microbial communities toward their respective donor profiles (obese or lean) but did not significantly affect body weight or routine serum biochemical parameters during the experimental period. These findings suggest that gut microbiota remodeling may influence metabolic processes prior to detectable phenotypic changes in cats.