Effects of dietary cellulose on clinical and gut microbiota recovery in dogs with uncomplicated acute diarrhea: a randomized prospective clinical trial.

Objective: To assess the impact of dietary fiber supplementation with cellulose on clinical course, fecal consistency, and intestinal microbiota composition in dogs with uncomplicated acute diarrhea (AD).

Methods: From September 2022 to November 2023, a total of 19 dogs presenting with uncomplicated AD were included in this prospective, randomized, and double-blinded clinical trial. The time to resolution of diarrhea was evaluated via owner surveys and a fecal scoring chart. The client-owned dogs were randomly assigned to a cellulose group (CG) or control group. The intestinal microbiota was analyzed via quantitative PCR.

Results: A marginally significant, faster improvement in stool consistency on day 1 was observed in the CG (P = .09). All dogs improved clinically, with a median recovery time of 3.0 days in the CG and 3.2 days in the control group (range, 1 to 6 days in both groups). There was no significant difference regarding the Canine Acute Diarrhea Severity index or composition of the intestinal microbiota during the study.

Conclusions: All dogs with uncomplicated AD exhibited rapid clinical improvement and recovery of the core intestinal microbiota within the first few days. Cellulose improved the fecal consistency in a subset of dogs, and intestinal dysbiosis was mild and self-limiting.

Clinical relevance: The administration of dietary cellulose has the potential to accelerate improvements of stool consistency. Mild changes in pathobionts, such as an increased amount of Clostridium perfringens, are self-limiting; thus, antibiotic intervention is not warranted.