Accumulating evidence has shown a significant relationship between the GI microbiota and GI health of the host. An alteration in the intestinal microbial community structure, referred to as intestinal dysbiosis, can significantly affect host GI health and play a pivotal role in the pathogenesis of GI diseases. This study aimed to evaluate the relationship between an enteric pathogen and intestinal dysbiosis, and to describe the functional aspects of the intestinal microbiota in dogs with GI diseases. Firstly, this study evaluated the relationship between diarrhea, intestinal dysbiosis, and the presence of C. perfringens by quantitative PCR and its enterotoxin (CPE) by ELISA in feces. The presence of CPE as well as fecal dysbiosis were associated with GI disease. However, the presence of C. perfringens was not indicative of GI disease. Furthermore, an increased abundance of enterotoxigenic C. perfringens may be a feature of intestinal dysbiosis that is associated with GI disease. Secondly, this study characterized fecal concentrations of short-chain fatty acids (SCFAs) in dogs with clinical signs of chronic GI disease. Dogs with clinical signs of chronic GI disease had decreased fecal concentrations of acetate, propionate, and total short-chain fatty acids. Finally, this study characterized the fecal microbiota and serum metabolite profiles in dogs with idiopathic inflammatory bowel disease (IBD) by using 454-pyrosequencing of 16S rRNA genes and an untargeted metabolomics approach. This study also evaluated the effects of 3 weeks of medical treatment on both the GI microbiota and serum metabolite profiles in dogs with IBD. Significantly lower bacterial diversity and distinct microbial communities were observed in dogs with IBD compared to healthy control dogs. Based on the metabolite profiles, this study identified several potential biomarkers. Although a clinical improvement was observed after medical therapy in all dogs with IBD, this was not accompanied by significant changes in the fecal microbiota or in serum metabolite profiles, suggesting an ongoing intestinal disease process. In conclusion, the findings of these studies provided new insights into the pathogenesis of canine GI diseases and highlight the importance of balanced microbial communities for canine GI health.
