Evaluation of the efficacy of afoxolaner against two European dog tick species: Dermacentor reticulatus and Ixodes ricinus.

The acaricidal efficacy of a novel oral formulation of afoxolaner (NEXGARD(®), Merial) against two European tick species was assessed in dogs experimentally infested with Ixodes ricinus and Dermacentor reticulatus. Three studies, each characterized by a negative controlled randomized block design, were conducted with a total of 52 beagle or mongrel dogs of both sexes. Starting 2 days before treatment, each dog was infested weekly with approximately 50 ticks. The number of live ticks was counted at 48 h post-treatment (Day 2) as well as 48 h following each infestation on Days 9, 16, 23, and 30. Afoxolaner, administered at an average dose of 2.7 mg/kg bodyweight (range 2.5-2.9 mg/kg), rapidly eliminated the pre-existing tick infestations with over 99% acaricidal efficacy and controlled the weekly re-infestations for up to 30 days post treatment with over 96% efficacy on both tick species. Afoxolaner provides excellent acaricidal efficacy against these two major European tick species using the oral route of administration.