Efficacy of a Formulation Containing Imidacloprid and Moxidectin Against Naturally Acquired Ear Mite Infestations (Psoroptes cuniculi) in Rabbits

The purpose of this study was to evaluate the efficacy of a topical formulation containing imidacloprid and moxidectin for eradication of Psoroptes cuniculi in rabbits. Fourteen adult rabbits from a rabbit husbandry were enrolled in the study. Rabbits were treated with 40 mg imidacloprid and 4 mg moxidectin monthly as spot-on on Days 0, 30, and 60. No other treatment or environmental decontamination was performed during the trial. On Days 0, 30, 60, and 90, all rabbits were examined, and epidermal debris was collected from both auricular areas and the external ear canal for microscopic examination. Clinical signs had subsided by Day 30 in 13/14 rabbits and almost no signs of recurrence were apparent in the following weeks. All epidermal samples were negative by Day 90. No adverse reacIntern J Appl Res Vet Med • Vol. 3, No. 4, 2005 Intern J Appl Res Vet Med • Vol. 3, No. 4, 2005 282 antelopes, cattle, and sheep. – 9 The ear mite is mainly found in the external auricular meatus of the ear and inside the ear pinnae; it is common to discover that only one ear is affected. Psoroptes cuniculi infestations in domestic rabbits are recognized in 2 clinical pictures: characteristic psoroptic “ear canker” causing puff pastry-like crusts, excoriations, massive pruritus, and occasionally aural hematomas due to intense head shaking or scratching 0 , 1 ; and “extraauricular” mange extensively described by Ribbeck and Ilchmann 2 and Guilhon. 3 C u t l e r 4 reported an ectopic P. cuniculi infestation in a pet rabbit, with severe lesions on the skin of the caudoventral abdomen. Bates observed the ectopic form in 5% of all P. cuniculi-infested rabbits of his study, showing lesions extending to the base of the ears, the cheeks, dewlap, face, and between the digits of both hind feet. A new dermal product has been developed containing imidacloprid and moxidectin (Advocate, Bayer) that is administered as a viable topical application to the skin at a single site on dogs and cats. No information is available on the efficacy of this preparation in rabbit “ear canker.” There are currently no licensed veterinary products specifically indicated for the therapy of ectoparasites in rabbits. Thus, veterinarians need to rededicate pharmaceuticals normally used for other animal species. The present clinical study was conducted to evaluate the efficacy and tolerance of a spot-on formulation with imidacloprid and moxidectin in the treatment of P. cuniculi mange in naturally infested rabbits. MATERIALS AND METHODS Fourteen adult rabbits with a naturally occurring P. cuniculi infestation were enrolled in this field study. All rabbits were from the same rabbit husbandry in the western Bodensee area (Baden-Wuerttemberg) and kept exclusively in cages indoors during the treatment period. Ages ranged from 6 months to 1 year with a mean age of 9 months. On Day 0, all animals were individually weighed. Body weight of the measured rabbits ranged from 2.1 to 3.7 kg with a mean body weight of 2.65 kg. In the course of this study, one female was pregnant. Owners reported about reduced appetence and increasing restlessness in their animal husbandry over the last weeks. Moreover, remarkable crusts in the pinnae were observed.