A double-blind, placebo-controlled evaluation of orally administered heat-killed Enterococcus faecalis FK-23 preparation in atopic dogs.

Background: Gastrointestinal microbiome modulation is reported to be an effective therapy to reduce the clinical signs of canine atopic dermatitis (cAD). The killed strain of Enterococcus faecalis FK-23 has been shown to reduce allergic responses in mice and people.

Objective: The aim of this multicentre, double-blinded, placebo-controlled study was to evaluate the safety and efficacy of an orally administered heat-killed E. faecalis FK-23 preparation (FK-23p) for the control of cAD.

Methods: Thirty-nine client-owned dogs with clinical signs of nonseasonal cAD were enrolled by 10 veterinarians at 15 hospitals. Methods: Dogs were randomized to either FK-23p at a dose of ≥100 mg/kg/day or placebo. Owner-assessed pruritus Visual Analog Scale (pVAS), clinician-assessed Canine Atopic Dermatitis Extent and Severity Index, 4th iteration (CADESI-4) and daily medication scoring (DMS) were evaluated on days 0, 28, 56 and 84. Owners and clinicians were interviewed about the overall response to treatment (RTT), after the study.

Results: The CADESI-4 significantly decreased in the FK-23p group compared to the placebo group, by Day 84 (P = 0.035; Wilcoxon-Mann-Whitney U-test). There was no significant difference in pVAS and DMS between the groups. Owners and clinicians reported significantly better RTT in the FK-23p group than the placebo group (P = 0.043 and 0.002, respectively; Wilcoxon-Mann-Whitney U-test). There were no adverse events associated with FK-23p.

Conclusions: Oral administration of FK-23p provided a small, but measurable benefit when used as an adjunct treatment, in reducing clinical signs of atopic dogs.