Onset of efficacy and residual speed of kill over one month of a topical dinotefuran-permethrin-pyriproxyfen combination (Vectra®3D) against the adult cat flea (Ctenocephalides felis felis) on dogs

- We examined adulticidal flea efficacy of a topical DPP combination on dogs.
- Adulticidal efficacy was assessed 2 and 6 h after treatment and after weekly infestations.
- The DPP combination had >96.4% initial efficacy in 6 h and >96.8% residual efficacy in 2 h.

This study was designed to assess the onset of therapeutic and residual insecticidal efficacy of a topical ectoparasiticide (Vectra®3D, DPP) on dogs over one month against the cat flea, Ctenocephalides felis felis. Adult dogs (n = 32, 11.0-18.7 kg) were infested with 100 adult fleas on days −6, −2, 7, 14, 21 and 28. Based on flea retention, the dogs were allocated in two groups and were treated topically on day 0 with a control solution (CS) or DPP. Each group was divided in two subgroups in which live fleas were counted by combing the dogs 2 or 6 h after treatment and at each re-infestation. The insecticidal efficacy was calculated using arithmetic and geometric means at each time point. The flea retention rate ranged from 64.0 to 86.5% in the CS group throughout the study. Based on arithmetic means, the therapeutic efficacy was 96.4% 6 h post-treatment and residual efficacies ranged from 96.8 to 99.9% 2 h after each re-infestation. The residual speed of killing effectiveness, >96% at 2 h, persisted for one month after treatment. DPP administration was well tolerated. This study confirms that DPP starts killing fleas within 2 h after treatment and reaches efficacy levels >95% at 6 h. We have shown that DPP kills >96.8% of fleas for one month after treatment within 2 h after infestation.