A Randomised Placebo-Controlled Study to Evaluate the Efficacy and Safety of a Two-Dose Topical Terbinafine and Betamethasone Gel for the Treatment of Yeast (Malassezia pachydermatis) Otitis Externa in Dogs.

BACKGROUND: Otitis externa (OE) with Malassezia pachydermatis overgrowth with limited bacterial involvement is common in dogs. Treatment with products containing antibiotics is unnecessary and not consistent with judicious use of antimicrobials. OBJECTIVES: To evaluate the efficacy and safety of an otic gel containing 1% terbinafine and 0.1% betamethasone acetate for the treatment of yeast-predominant canine OE. ANIMALS: 239 privately owned dogs were enrolled. MATERIALS AND METHODS: Inclusion criteria were an otitis index score (OTIS3) of ≥ 6 and yeast-predominance on ear swab cytological evaluation. Dogs received either the study product containing terbinafine and betamethasone (TBG) or placebo (saline) on Day (D) 0 and D7. Follow-up visits were on D7, D14, D28 and D45. Clinical success was defined as an OTIS3 score ≤ 3 on D45. Overall clinical response (by the veterinary surgeon and owner) and yeast cytological count reduction also were assessed. Safety was evaluated based on clinical assessments, haematological and clinical chemical analysis, urinalysis and adverse events. RESULTS: The treatment success was significantly higher in the treated group compared to the placebo group (62.9% versus 20.0%, p < 0.0001). Dogs receiving TBG had a treatment response described as 'excellent' or 'good' by 61.9% and 71.1% of veterinary surgeons and owners, respectively. The safety evaluation demonstrated that the otic gel was safe. CONCLUSIONS AND CLINICAL RELEVANCE: Efficacy and safety of an otic gel for the treatment of canine OE associated with Malassezia pachydermatis were demonstrated.