4% acaricidal efficacy Screening Library against D. reticulatus and over 99.6% against I. ricinus up to Day 30 ( Table 3) when infestations occurred after treatment (prophylactic efficacy). No adverse effects related to treatment were observed. A single oral treatment with the chewable formulation of afoxolaner achieved 100% therapeutic efficacy for treating pre-existing infestations by I. ricinus and D. reticulatus. It also controlled re-infestations of ticks within 48 h for 4 weeks after treatment as demonstrated by the prophylactic efficacy, which was over 96.4% for the 2 studies against D. reticulatus and over 99.6% for the I. ricinus study. No difference was observed

in efficacy against D. reticulatus ticks between fasted (Study A) and fed (Study B) dogs. Treated dogs in all three studies accepted the afoxolaner chews without adverse reactions, based on hourly post-treatment observations and daily observations. Z-VAD-FMK molecular weight The acaricidal efficacy of afoxolaner against I. ricinus and D. reticulatus observed in these studies

was similar to what is usually observed with topical products. For example, against I. ricinus, two spot-on solutions, one with pyriprole and one with permethrin/imidacloprid provided a curative efficacy of 100% and 67.0%, respectively on Day 2, and greater than 98.7% prophylactic efficacy up to 30 days when assessed 48 h after tick infestations ( Epe et al., 2003 and Schuele et al., 2008). In a study comparing three topical treatments against D. reticulatus ( Tielemans et al., 2010), the efficacies were 100%, 76% and 70% on Day 30 for fipronil/(S)-methoprene, permethrin/imidacloprid and metaflumizone/amitraz, respectively. The oral formulation of afoxolaner is the first one to provide an efficacy against tick for a month,

as it is described for topical products. Nevertheless, no direct comparison is available. The systemic distribution of the tested product offer advantages compared to the topical formulations. One benefit is the lower possibility of exposure of the owner during the time necessary for a topical product to be absorbed through the skin of a treated dog. Another significant advantage of an orally administered, systemically active product is that rainy conditions, Carnitine dehydrogenase shampooing, or other concurrent topical treatments will not interfere with the efficacy (Beugnet and Franc, 2012). In conclusion, the chewable formulation containing the new insecticide–acaricide afoxolaner is a convenient and efficacious ectoparasiticide treatment for dogs that treats and prevents tick infestations for up to 1 month. The work reported herein was funded by Merial Limited, GA, USA. The authors are current employees or contractors of Merial. The authors gratefully acknowledge the expert contributions of all collaborators from ClinVet International (Pty) Ltd. (South Africa), Merial CRSV (France) and Merial Limited (USA) in conducting all three studies to high standards.