The objective of this study was to determine how a veterinary gastrointestinal diet impacts the fecal characteristics, metabolites, and microbiota concentrations of adult cats treated with metronidazole. All cats were fed a leading grocery brand diet (GBD) during a 2-wk baseline, dosed orally with metronidazole (20 mg/kg BW twice daily) for 2 wk, then randomly allotted to one of 2 treatments [GBD; BLUE Natural Veterinary Diet GI Gastrointestinal Support (BB)] and fed for 4 wk. Fecal scores were recorded daily and fresh fecal samples were collected at weeks 2, 4, 5, 6, 7, and 8 to assess fecal characteristics, microbiota populations, and metabolite and bile acid (BA) concentrations. Metronidazole increased fecal scores (looser stools), altered relative abundances of 78 bacterial genera and BA profiles (increased primary BA; reduced secondary BA), and increased dysbiosis index. Fecal outcomes varied during recovery. Recovery of 16 bacterial genera was impacted by diet. Dysbiosis index and bacterial alpha diversity were not affected by diet. Our data demonstrate that metronidazole is a powerful antibiotic and may have long-lasting effects on the gut microbiota and metabolites of cats. Feeding a gastrointestinal diet may aid in the recovery of several markers of microbial function (e.g., metabolites).

Read the full article in the Journal of Animal Science.