Incidence Rate of Otitis Externa Episodes in Atopic Dogs Is Reduced by a Therapeutic Diet in a 6-Month Randomised, Blinded, Controlled, Clinical Trial.

Abstract

BACKGROUND: Recurrent otitis externa (OE) episodes commonly affect dogs with canine atopic dermatitis (cAD) despite ongoing cAD treatment. OBJECTIVE: To determine if a therapeutic diet with active ingredients targeting the skin barrier and allergy pathways reduces the incidence rate of OE. ANIMALS, MATERIALS AND METHODS: Thirty-four client-owned dogs with active erythroceruminous OE&#x2009;+&#x2009;cAD (not necessarily active) were randomised to test (n&#x2009;=&#x2009;16) or control diet (n&#x2009;=&#x2009;18), fed for up to 6&#x2009;months. Dogs had to be in remission by Month (M)1 after initial OE treatment. Outcomes included incidence rate (percentage of dogs with &#x2265;&#x2009;1 OE episode), 0-3 Otitis Index Score (OTIS-3), cAD Extent and Severity Index, 4th iteration (CADESI-04), and medication score (medication required to control OE and/or cAD) at M3 and the end-point, defined as each dog's last on-study data. RESULTS: The incidence rate was significantly lower in the test versus control group (25% vs. 61%, p&#x2009;<&#x2009;0.01). OTIS-3 and CADESI-04 improved significantly between baseline and M3 in both groups (control: p&#x2009;=&#x2009;0.003 and p&#x2009;<&#x2009;0.001; test: each p&#x2009;=&#x2009;0.001). Between M3 and the end-point, OTIS-3 and CADESI-04 rebounded significantly in the control (p&#x2009;=&#x2009;0.025 and p&#x2009;=&#x2009;0.026) and not in the test group (p&#x2009;=&#x2009;0.139 and p&#x2009;=&#x2009;0.909). CADESI improvement from baseline was maintained at the end-point in the test (p&#x2009;<&#x2009;0.001) and not in the control group (p&#x2009;=&#x2009;0.227). Medication score improved significantly throughout the diet duration in the test group (baseline to M3, M3 to end-point, and baseline to end-point) versus no improvements in the control group. CONCLUSION AND CLINICAL RELEVANCE: A therapeutic diet for cAD helped to sustain improvements in aural manifestations.