Oral fecal microbial transplant for parvovirus in the outpatient setting: a randomized controlled trial to evaluate a practical and low-cost intervention

Objective: To evaluate commercially available oral capsules providing fecal microbial transplant (FMT) as a practical option for adjunctive treatment of canine parvovirus (CPV) in an outpatient setting. We hypothesized that treatment with FMT capsules would improve survival and hasten resolution of clinical signs compared to placebo. Methods: This blinded, randomized controlled trial evaluated oral FMT capsules in shelter dogs with CPV treated with an outpatient protocol (September 2022 to August 2024). Eligible dogs were randomized to receive adjunctive FMT or placebo, with 3 dosing regimens assessed. The primary outcome was time to recovery; secondary outcomes included survival, escalation to ICU, and resolution of clinical signs. Results: 101 dogs were enrolled, of which 52 were in the control group and 49 received FMT. Dogs that survived without escalation to ICU-level care in both the control (n = 42) and FMT groups (32) had a median duration to recovery of 5 days (P = .872). There was a 94% (49 of 52) survival rate in the control group compared to 82% (40 of 49) for the group receiving FMT (P = .051); there was no significant difference in survival between groups when controlling for age or weight (OR, 3.18; 95% CI, 0.74 to 17.28; P = .139). Conclusions: There was no evidence that oral FMT capsules hastened recovery or improved short-term survival rate in an outpatient setting. Future work is needed to determine whether oral FMT has negative effects in dogs with CPV. Clinical Relevance: This study provides evidence that oral FMT treatment may not be helpful in the outpatient treatment of CPV.