Assessment of the Ear Mite (Otodectes cynotis) Infestation and the Efficacy of an Imidacloprid plus Moxidectin Combination in the Treatment of Otoacariosis in a Hungarian Cat Shelter

Abstract

Two separated field studies were carried out in Hungary to assess Otodectes cynotis infestation and to evaluate the efficacy of 10% imidacloprid and 1.0% moxidectin spot-on for cats against ear mites in a cat shelter. Mite infestation was studied with direct, otoscopic examination of the external ear canals and with the presence or absence of live mites in samples taken with cotton-tipped swabs from both ears of each animal. Fifteen out of 100 cats selected randomly were found to be infested. Seven animals showed severe clinical signs of otitis externa consistent with O. cynotis infestation. These cats were restless, shaking their heads and scratching their ears. Alopecia, wounds caused by self-injuries and dermatitis were seen in and around the ears of the two cats having most severe clinical signs. The other infested cats did not show any clinical signs, only dark brown exudates ranging frommoist and waxy to crumbly and flaky accumulated at the deeper part of the external ear canals. Ten cats were randomly assigned to the treatment group and five animals to the untreated control group. Each cat of the treated group was weighed and treated with the recommended dosage of 10% imidacloprid and 1.0%moxidectin spot-on on day 0. Only those three cats were found to be infested with live ear mites on day 9, which had showed the most severe clinical signs of otitis externa before treatment. The black-brown cerumen or scab was drier in their ear canals than nine days earlier. Some live and dead mites were found only by microscopic examination of aural debris. The efficacy of 10% imidacloprid and 1.0%moxidectin against O. cynotis was 100% on days 16 and 30. Direct and otoscopic examinations of both ears of treated animals could not reveal mite movement. A very small amount of dry material was found in the ear canals of the formerlymost affected cats. No or some dried up mites occurred in samples taken with cotton-tipped swabs from all cats which had no clinical signs of otoacariosis. The external ear canals of untreated cats continued to contain large amounts of dark brown, waxy cerumen and their ear swab samples contained live ear mites until the end of study.