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

This controlled laboratory study demonstrated the residual speed of efficacy of an imidacloprid/flumethrin collar (Seresto (R), Bayer) for the control of ticks (Dermacentor variabilis, Amblyomma americanum) at 6 and 12 hours post-infestation on dogs when compared to oral fluralaner (Bravecto (R), Merck). Dogs were randomised by pre-treatment tick counts: Group 1) imidacloprid 10 % (w/w)/flumethrin 4.5 % (w/w) collar, 2) fluralaner (dosage 25.1-49.4 mg/kg), and 3) non-treated controls. Ticks (50/species/dog) were infested on days 3, 14, 21, 28, 42, and 56 followed by 50 D. variabilis on days 70 and 84. Live and dead attached ticks were counted 6 and 12 hours later. Efficacy against both species at 6 and 12 hours for Group 1 was 94-100 %. Efficacy for Group 2 against both species at 6 hours was 4-69 %; efficacy at 12 hours was 8-100 %. Live (attached and non-attached) tick counts at 6 hours in Group 1 were significantly lower (p <= 0.05) than counts in Group 2 and 3 on all days. At 12 hours, live counts were significantly lower (p <= 0.05) in Group 1 than Group 2 for D. variabilis from days 56-84 and for A. americanum from days 28-56. There were significantly fewer (p <= 0.05) total ticks (total live and dead attached) on dogs in Group 1 compared to Group 2 and 3 at all time points. 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 fluralaner as early as 6 hours post-infestation on all challenge days.