Effect of Wheat Dextrin Fiber on the Fecal Microbiome and Short-Chain Fatty Acid Concentrations in Dogs: Randomized, Single-Blinded, Parallel-Group Clinical Trial

The purpose of this study was to assess the practical implications of supplement- ing soluble fiber in the diet of dogs. Dogs with a history of managed or active chronic enteropathy were randomized to receive either wheat dextrin (fiber group) or maltodex- trin (placebo group) mixed with food once daily for 28 days. Owners recorded a daily fecal score one week prior to and during the supplementation period. Shallow shotgun sequencing, quantitative PCR abundances of core bacterial taxa, and short-chain fatty acid (SCFA) concentrations via gas chromatography/mass spectrometry were performed on fecal samples collected before and after supplementation. Seventeen dogs completed the study (fiber group: nine dogs; placebo group: eight dogs). The change in fecal score differed between groups, with the fiber group developing softer stools (p = 0.03). Alpha diversity, quantified PCR abundances of the SCFA-producing taxa, and fecal SCFA concentrations were not different after supplementation in either group. Fecal microbial communities differed between baseline and day 28 for fiber and placebo groups (p = 0.02, respectively); however, the size effect (ANOSIM R = 0.18 and R = 0.26, respectively) was minimal. In this small group of dogs fed variable commercial diets, the additional intake of wheat dextrin powder supplement was well accepted, but had minimal discernable clinical benefit, and could soften stools.