Treatment of Harvest Mite Infestation in Dogs Using a Permethrin 54.5% and Fipronil 6.1% (Effitix(®)) Topical Spot-On Formulation

Background—The study aims to assess the efficacy of a permethrin 54.5%-fipronil 6.1%-based spot-on solution in dogs naturally infested with Neotrombicula in an open-label controlled study. Methods—Ten naturally infested dogs received one drop per affected site on day (D) 0, and on D14, the rest of the pipette was applied on the skin between the shoulders. Five dogs served as sentinels. Parasite score (0–3), skin lesions (0–4), and investigator pruritus scale (0–4) were assessed on D0, D1, D14, and D28. Results—No treated dogs developed adverse reactions. Parasite score of sentinel dogs was maintained between 1.8 (D0, D1, and D28) and 2.2 (D14). In treated dogs, D0 parasite score was 2.4. It was significantly reduced from D1 (0.5; p < 0.002) to D28 (0.1; p < 0.002). The lesion score was 2.9 on D0 and D1; it was significantly reduced on D14 (0.6; p < 0.002) and D28 (0.1; p < 0.002). Similarly, investigator pruritus scale (D0, 2.2) scores significantly decreased on D14 (0.4; p < 0.004) and D28 (0.2; p < 0.002). Conclusions—The combination permethrin-fipronil appears to be well-tolerated, rapidly and durably effective in the control of localized canine harvest mite infestation.