Antiparasitic Efficacy of a New Fipronil-based Spot-on Formulation on Dogs Experimentally Infested with Ticks Dermacentor reticulatus

In this blinded, randomized, monocentric study, we evaluated the antiparasitic efficacy of a new fipronil formulation (Effipro® spot-on, Virbac) on dogs experimentally infested with ticks, Dermacentor reticulatus. The study was performed on three groups (three males and three females per group) of beagles: untreated control, reference drugtreated, and test drug-treated group. The reference drug (Frontline® spot-on, Merial) was administered in the same recommended manner as for the test drug, ie, once on Day 0 at a dose of 1.34 mL/dog. Dogs were repeatedly infested with ticks (25 males and 25 females) on Days -7, -2, 7, 14, 21, 28, 35, 42, 49, 56, and 63. Except for the Day -2 infestation, ticks were collected 2 days (48 ± 2 hr) after each infestation, and counted according to their viability, attachment, and engorgement status. The ticks applied on Day -2 were removed and counted on Day 2 or 48 ± 2 hr post-treatment. All dogs were monitored for possible adverse events in addition to their general and specific health status. Our data indicated that compared with the untreated control, both Frontline® and Effipro® group animals showed ~100% reduction of viable tick counts for up to 6 weeks post-treatment (P ≤ 0.005). Afterwards, both Frontline® and Effipro® showed slightly reduced acaricidal activities, eg, 97.3% and 96.3%, respectively, at the 8-week time point. The immediate as well as sustained antiparasitic activities of the two drugs were consistent and indistinguishable from each other throughout the observation period of 65 days. No adverse reactions associated with the drugs were observed in any of the treated animals. Antiparasitic Efficacy of a New Fipronil-based Spot-on Formulation on Dogs Experimentally Infested with Ticks Dermacentor reticulatus Stephane Bonneau1 Sandeep Gupta2 Laurence Maynard1 Hyone-Myong Eun1* 1R&D Department, Virbac S.A. 13th Avenue, LID, 06511 Carros, France 2Charles River Laboratories Preclinical Services Ireland Ltd. Carrentrila, Ballina, Co Mayo, Ireland *Dr. H.M. Thomas Eun E-mail : [email protected] T : 33 (0)4 9208 7960, F : 33 (0)4 9208 7738