Twenty-six dogs, hyper immunized against holocyclotoxin, 1 to 9 years of age and weighing from 25.0 to 46.0 kg, were ranked within gender in descending order of tick carrying capacity and randomly allocated to Groups A, B and C. Ten to eleven unfed adult female Ixodes holocyclus were manually attached to each dog on Days -1, 7, 14, 21 and 28. On Day 0, Group B dogs were treated with the test formulation Promeris for Dogs (15% w/v metaflumizone and 15% w/v amitraz). Group C dogs were treated with the positive control formulation Frontline®Plus, Merial (100 g/L fipronil and 90 g/L (S)-methoprene). Group A remained the untreated control group. Ticks were counted for 3 days following treatment or tick attachment. Ticks were classified according to viability (healthy/ sick/ dead). The test product, Promeris for Dogs, provided more rapid efficacy than the commercial formulation, Frontline®Plus, in controlling pre-existing infestations with 93.4% efficacy versus 39.4% efficacy on Day 1. The persistent activity of the test product versus the control product was 100% versus 98.8% on Day 3; 100% versus 100% on Day 10; 100% versus 100% on Day 17; 96.1% versus 61.9% on Day 24 and 86.2% versus 51.7% on Day 31 when calculated by geometric mean of healthy attached ticks. It was concluded that in this study the test product Promeris for Dogs was safe and efficacious in controlling I. holocyclus on dogs for up to 21 days post-treatment.

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