Effects of Synbiotic Administration on Gut Microbiome and Fecal Bile Acids in Dogs with Chronic Hepatobiliary Disease: A Randomized Case–Control Study

Alteration in the gut microbiome in human patients with chronic liver disease is a well-known pathophysiological mechanism. Therefore, it represents both a diagnostic and therapeutical target. Intestinal dysbiosis has also been identified in dogs with chronic liver disease, but clinical trials evaluating the effectiveness of synbiotic administration are lacking. Thirty-two dogs with chronic hepatobiliary disease were equally randomized into two groups: one treated with a synbiotic complex for 4-6 weeks (TG) and one untreated control group (CG). All dogs underwent clinical evaluation, complete anamnesis, bloodwork, abdominal ultrasound, fecal bile acids, and gut microbiome evaluation at T0-T1 (after 4-6 weeks). Treated dogs showed a significant reduction in ALT activity (<i>p</i> = 0.007) and clinical resolution of gastrointestinal signs (<i>p</i> = 0.026) compared to control dogs. The synbiotic treatment resulted in a lower increase in <i>Enterobacteriaceae</i> and <i>Lachnospiraceae</i> compared to the control group but did not affect the overall richness and number of bacterial species. No significant changes in fecal bile acids profile were detected with synbiotic administration. Further studies are needed to better evaluate the effectiveness of synbiotic administration in these patients and the metabolic pathways involved in determining the clinical and biochemical improvement.