Comparative Efficacy of an Imidacloprid/Flumethrin Collar (Seresto®) and an Oral Afoxolaner Chewable (NexGard®) against Tick (Dermacentor variabilis and Amblyomma americanum) Infestations on Dogs: a Randomised Controlled Trial

Abstract

This randomised controlled laboratory study demonstrated the residual speed of efficacy of an imidacloprid/flumethrin collar (Seresto ® , Bayer) for the control of ticks (Dermacentor variabilis, Amblyomma americanum) at 6 and 12 hours postinfestation on dogs when compared to oral afoxolaner (NexGard ® , Merial). Dogs were randomised by pre-treatment tick counts: Group 1) imidacloprid 10 % (w/w) / flumethrin 4.5 % (w/w) collar, 2) afoxolaner chewable (dosage 3.1 -6.2 mg/kg), and 3) non-treated controls. Ticks (50/species/dog) were infested on days 3, 14, 21, and 28; live (attached and non-attached) and dead attached ticks were counted 6 and 12 hours later. Efficacy against live D. variabilis at 6 hours for Group 1 was 95 -100 % and for Group 2 was 38 -48 %; efficacy at 12 hours for Group 1 was 97 -100 % and for Group 2 was 27 -59 %. Efficacy against A. americanum at 6 hours for Group 1 was 94 -100 % and for Group 2 was < 0 -38 %; efficacy at 12 hours for Group 1 was 98 -100 % and for Group 2 was 1 -40 %. Live and total (total live and dead attached) tick counts in Group 1 against both tick species were significantly lower (p ≤ 0.05) than Group 2 and 3 at all time points. The number of live or total ticks on Group 2 dogs was never significantly lower when compared to the respective number of ticks on Group 3 (controls). This study demonstrated that an imidacloprid/flumethrin collar was highly efficacious (94 -100 %) at repelling and killing ticks on dogs at 6 and 12 hours post-infestation and was more efficacious than afoxolaner on all challenge days.