Evaluation of the efficacy of an imidacloprid 10% / moxidectin 1% spot-on against Otodectes cynotis in cats

Abstract

The aim of this study was to determine whether a single treatment or two treatments, four weeks apart, with a novel formulation of Imidacloprid 10% plus Moxidectin 1%, applied at a dose of 0.1ml / kg body mass, would be effective in the treatment of ear mite, Otodectes cynotis, infestations in cats. Thirty cats infested with O. cynotis were allocated to three groups of 10 each by randomisation through minimization with body weight as the primary criterion. Group 1 served as a negative placebo treated (Days 0 and +28) control. Group two received a single treatment with the Imidacloprid / Moxidectin solution on Day 0 and a placebo treatment on Day +28. Group 3 was treated with the Imidacloprid / Moxidectin solution on Days 0 and +28. Treatments were blinded and were administered as topical applications. The various groups were kept in adjacent environmentally controlled rooms. Eight days after the first treatment and thereafter at fortnightly intervals, the ears of the cats were examined for the presence of ear mites by using an otoscope, ear scrapes and dry cotton swabs. Assessments on Day +50 were performed on anaesthetised cats. Mites were observed in the ears of the untreated control cats on all assessment days. A single treatment with the Imidacloprid / Moxidectin solution resulted in a treatment success rate (cure rate) of 80% 50 days after treatment. Two treatments with the Imidacloprid / Moxidectin solution, four weeks apart, cured all cats of O. cynotis infestation on assessment 22 days after the second treatment.