Clinical trial reveals limited clinical and microbiome effects following oral fecal microbiota transplantation in dogs with chronic enteropathy responsive to tylosin.

OBJECTIVE

To evaluate clinical response and fecal biomarkers in dogs with tylosin-responsive enteropathy (TRE) treated with oral fecal microbiota transplantation (FMT).

METHODS

In this prospective, randomized, double-blind, placebo-controlled trial (conducted between August 1, 2020, and December 31, 2022), 14 client-owned dogs with confirmed tylosin-responsive enteropathy entered the treatment phase. Dogs received oral FMT (n = 7) or placebo (7) for 4 weeks; 1 placebo-treated dog was excluded (pyometra), leaving 7 FMT-treated and 6 placebo-treated dogs for analysis. Canine Chronic Enteropathy Clinical Activity Index, fecal consistency, and fecal biomarkers (dysbiosis index, core bacteria, bile acids, short-chain fatty acids, lactate, and calprotectin) were assessed at pretreatment and posttreatment visits. Intestinal permeability was evaluated with serum iohexol. Analyses were limited to pre- and posttreatment comparisons.

RESULTS

Relapse occurred in 2 of 7 FMT-treated dogs (28.6%) and 3 of 6 placebo-treated dogs (50.0%). The dysbiosis index decreased over time in both groups, with no treatment effect. Faecalibacterium spp increased, with higher posttreatment values in the FMT group, whereas Turicibacter spp increased in both groups. Peptacetobacter hiranonis increased over time without between-group differences. Bile acid conversion was observed in a subset of dogs without group differences. Other biomarkers showed no consistent treatment-specific effects.

CONCLUSIONS

Oral FMT was associated with variable microbiome changes and inconsistent clinical response, with no clear treatment-specific effects compared with placebo. These findings support further evaluation of optimized microbiome-based therapies in larger studies.

CLINICAL RELEVANCE: Oral FMT may serve as an adjunctive strategy for microbiome modulation in dogs with chronic enteropathy; however, clinical benefits were inconsistent and optimized protocols may be required.