Efficacy evaluation of lotilaner (Credelio™) in experimentally induced Otodectes cynotis infestations in cats.

Abstract

BACKGROUND: The ear mite, Otodectes cynotis, is pathogenic, highly contagious and a global cause of otitis externa and pruritus in cats and dogs. The present study evaluated the efficacy of a single oral application of lotilaner flavoured chewable tablets for cats (Credelio™; Elanco, Greenfield, IN, USA) in cats experimentally infested with O. cynotis. METHODS: Sixteen adult cats were experimentally infested with O. cynotis and confirmed to be mite positive by otoscopic examination. Infested cats were randomly assigned to one of two study groups. On day 0, a group of eight cats was treated once with Credelio™ at 7.0-11.8 mg lotilaner/kg body weight (i.e. at the lower end of the recommended dose range [6-24 mg/kg]), while in the control group eight cats were sham-dosed. All cats were dosed in a fed state. Otoscopic examinations for scoring the number of live mites and the amount of debris/cerumen were performed post treatment (p.t) on days 14 and 28. Ear flushing and microscopic viable mite counts were performed on day 28. RESULTS: A single oral dose of Credelio™ on day 0 resulted in a 99.6% reduction in O. cynotis geometric mean mite counts in the Credelio™-treated study group on day 28 recovered by ear flushing. Otoscopic live ear mite count scores on days 14 and 28 did not detect any mites in the Credelio™-treated group. In contrast to this 100% improvement, in the control group an improvement of otoscopic live mite scores was recorded in 25% (day 14) and 12.5% (day 28) of the cats, respectively. Additionally, a comparison of the debris scores to baseline data on day - 2 showed an improvement in 75% of the Credelio™-treated cats on day 14 and in 87.5% on day 28 and no or limited improvement (0% on day 14 and 12.5% on day 28) in the control group animals. CONCLUSIONS: The results of this study demonstrated that a single application of Credelio™ chewable tablets for cats at the lower end of the recommended dose range was highly efficacious (99.6%) in eliminating experimentally induced O. cynotis infestations and greatly improved clinical signs of otocariosis in cats by 28 days p.t.