Anti-feeding efficacy of Activyl® Tick Plus topical treatment of dogs against Phlebotomus perniciosus

Background: Topical permethrin treatment is known to prevent feeding of sandflies on dogs. This study investigated the anti-feeding efficacy and the immediate insecticidal efficacy (knock-down effect) of topical treatment of dogs with a new commercially available combination of indoxacarb and permethrin (Activyl (R) Tick Plus), compared with a negative control. Methods: Sedated dogs were individually exposed to unfed female sandflies in a darkened chamber for one hour 2, 7, 14, 21 and 29 days after treatment. Mean fly feeding and survival rates in the two groups after one hour of exposure were used to calculate the anti-feeding efficacy and the knock-down effect, respectively. Results: On Days 2, 7, 14, 21 and 29 post treatment, the anti-feeding efficacy was 99, 98, 96, 88 and 84% based on geometric means. The mean number of fed sandflies in the treated group was significantly lower than in the control group mean at every evaluation time point. The knock-down effect, measured at one hour after exposure of the flies to treated dogs, was 32, 27, 9, 0 and 4% based on geometric means, at the same time points. The number of dead flies was significantly higher in the treated group on Days 2 and 7 post-treatment. No adverse effects of treatment were observed at any time during the study. Conclusions: Activyl (R) Tick Plus treatment of dogs provided a high anti-feeding efficacy against Phlebotomus perniciosus from 2 to 21 days post treatment, with continuing significant anti-feeding to 29 days post-treatment, and was well tolerated. Some knock-down effect following one hour of exposure of flies to treated dogs was observed in the first week after treatment.