Effects of Synbiotic Supplementation on Fecal Characteristics and Microbiota in Dogs Submitted to an Abrupt Dietary Change

Stressful situations can negatively affect the intestinal microbiota and contribute to gastrointestinal disorders. This study investigated the effects of a synbiotic (SYN) on fecal characteristics and ammonia concentrations, selected fecal bacterial groups, and dysbiosis index (DI) of healthy adult Beagles undergoing an abrupt dietary change. Sixteen adult dogs were divided into two groups: a placebo (PLA, no supplementation, n = 8) and a SYN supplementation group (n = 8). Dogs from both groups were fed a highly digestible diet for 20 days. On day 21, all dogs underwent an abrupt transition to a less digestible diet, which they continued to receive for an additional 20 days. Fecal samples were collected on days 20, 22, and 40 to analyze fecal dry matter, score, ammonia, pH, microbiota, and DI. The SYN supplementation did not affect fecal characteristics or DI of dogs (p > 0.05). After dietary change, an increase in fecal Bifidobacterium and universal bacteria was observed only in the PLA group (p < 0.05). In addition, dietary transition increased DI and fecal Escherichia coli regardless of the SYN supplementation (p < 0.05). Dogs fed the highly digestible diet presented greater fecal Peptacetobacter hiranonis and lower Streptococcus, Bifidobacterium, Lactobacillus, and Bacteroides (p < 0.05). Dogs supplemented with SYN presented lower fecal Clostridium perfringens than the PLA group when fed the less digestible diet (p < 0.05). These results suggest that abrupt dietary change may promote alterations associated with intestinal dysbiosis in dogs. Moreover, SYN supplementation was associated with lower fecal C. perfringens abundance in dogs fed the less digestible diet.