We always hear about the gut microbiota of the colon, but what do we know about the microbiota of the small intestine?
Chronic inflammatory enteropathies are the most common cause of chronic vomiting and diarrhea in dogs involve a multifactorial pathogenesis in which immunological imbalance and alterations in the gut microbiota play a central role.
Most sequencing-based taxonomic studies have focused on the fecal microbiota, but always of the colon.
The study by the University of Madrid focused on the Characterization of the intestinal bacterial microbiota of dogs with inflammatory bowel disease (IBD) (n = 34) By duodenal biopsies and rectal fecal samples collected at the time of diagnosis and comparison with a group of healthy dogs (n = 12) using the Targeted sequencing of the 16S ribosomal RNA gene (16S rRNA) (Illumina MiSeq platform).
The results of the study
Firmicutes (68.68%) was the most abundant phylum in fecal samples, while Proteobacteria (43.68%) and Firmicutes (37.37%) were the most abundant phyla in duodenal biopsies. These results are consistent with those reported previously, where Proteobacteria was the most abundant phylum in duodenal biopsies and Firmicutes the most abundant in canine fecal samples.
The study showed that dogs with IBD have differences in fecal bacterial communities compared with healthy dogs, with lower relative abundance of Prevotellaceae, Erysipelotrichales, Lachnospiraceae, Acidaminococcales. On the other hand, a higher relative abundance of Enterococcaceae, Streptococcaceae, Enterobacterales, Enterobacteriaceae, and Escherichia-Shigella was detected. In addition, when assessing α-diversity, dogs with IBD showed less diversity in terms of species richness and abundance. In addition, the fecal microbiota of dogs with IBD was significantly different from that of healthy dogs.
Only a few changes in bacterial taxa were observed when evaluating the duodenum-associated microbiota by analysis of duodenal biopsy samples.
Fecal sampling as the best sampling method
Therefore, although intestinal inflammation mainly affects the small intestine in the IBD subjects of the study, fecal samples are a better finding, not only because of their easy availability, but also for the search of bacterial taxa as biomarkers of canine IBD.
Reference
Díaz-Regañón, D.;García-Sancho, M.; Villaescusa, A.; Sainz, Á.; Agulla, B.; Reyes-Prieto, M.; Rodríguez-Bertos, A.; Rodríguez-Franco, F. Characterization of the Fecal and Mucosa-Associated Microbiota in Dogs with Chronic Inflammatory Enteropathy. Animals 2023, 13, 326 . https://doi.org/10.3390/ani13030326.
