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

Background: Recurrent otitis externa (OE) episodes commonly affect dogs with canine atopic dermatitis (cAD) despite ongoing cAD treatment.ObjectiveTo 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 + cAD (not necessarily active) were randomised to test (n = 16) or control diet (n = 18), fed for up to 6 months. Dogs had to be in remission by Month (M)1 after initial OE treatment. Outcomes included incidence rate (percentage of dogs with ≥ 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 < 0.01). OTIS‐3 and CADESI‐04 improved significantly between baseline and M3 in both groups (control: p = 0.003 and p < 0.001; test: each p = 0.001). Between M3 and the end‐point, OTIS‐3 and CADESI‐04 rebounded significantly in the control (p = 0.025 and p = 0.026) and not in the test group (p = 0.139 and p = 0.909). CADESI improvement from baseline was maintained at the end‐point in the test (p < 0.001) and not in the control group (p = 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.