Abrupt changes in diet can result in gastrointestinal upset in dogs but, although undesirable in households, they might represent a research tool to induce a mild state of transitory dysbiosis. Therefore, this type of dietary intervention could serve as a model for assessing the effect of feed additives aimed at promoting a more resilient gut ecosystem. In the current study, we examined the effects of an abrupt dietary change by assessing its impact on coefficients of apparent total tract digestibility (ATTD) of macronutrients, fecal characteristics, and fecal microbiota composition and metabolites of healthy dogs. A total of 24 adult Beagles were initially fed an extruded dry kibble (DRY) for 29 d, with proportions (%) of protein, fat, and carbohydrates, on a dry matter basis, of 26%, 12%, and 52%, respectively. Subsequently, they were abruptly switched to a canned diet (WET), with the corresponding proportions of 43%, 29%, and 16%, and stayed with that diet for 29 d more. This dietary intervention induced increases in the ATTD of dry matter, organic matter, crude protein, and gross energy, while the nitrogen-free extract ATTD and the metabolizable energy of the diet decreased significantly (P < 0.05). Regarding fecal quality, diet change resulted in wetter and less-formed feces. The switch led to a marked decrease in Turicibacter and Lactobacillus abundance and increases in Fusobacterium, Peptacetobacter hiranonis, Escherichia coli, and Clostridium perfringens (P < 0.001), accompanied by transient increases of the dysbiosis index, and plasma immunoglobulin A and C-reactive protein concentrations (P < 0.05). Furthermore, the challenge modified the concentration and profile of fecal short-chain fatty acids (P < 0.01) and increased the concentration of fecal ammonia (P < 0.05). It also had a relevant impact on fecal polyamines, with lower concentrations observed in dogs fed the WET diet (P < 0.001), while monoamines such as indole and indole-3-acetic acid increased (P < 0.05). Some of the parameters studied continued to evolve towards the end of the trial, suggesting an adaptative process within the microbiota, after the dietary shift. These findings underscore the validity of our dietary model for inducing changes in the intestinal ecosystem and suggest ongoing adaptive processes. In conclusion, this model offers the potential for evaluating the efficacy of additives in fostering a resilient microbiota, thereby promoting strategies to enhance canine digestive health.
