Efficacy of a new combination of fipronil and permethrin (Effitix®) against Phlebotomus perniciosus in dogs.

Abstract Two controlled clinical trials were carried out to assess the anti-feeding and adulticidal effects of a spot-on combining fipronil and permethrin (Effitix ® , Virbac, Carros, France) against Phlebotomus perniciosus in dogs. The first study (Exp. A) was a dose-determination study in which 3 doses of permethrin (30 mg/kg, 60 mg/kg and 120 mg/kg) were compared. The second study (Exp. B) was an efficacy study using commercial dose of permethrin contained in Effitix ® (the minimum dose of permethrin applied to dogs was 60 mg/kg). Twenty four and twelve Beagle dogs with equal sensitivity to sandflies were included in Exp. A and in Exp. B, respectively. Dogs were challenged with female sandflies (50 per dogs in Exp. A and 80 in Exp. B) for 60 ± 5 min on Days – 7, 1, 7, 14, 21 and 28 (Day 0 being treatment day). Counts and engorgement determination of dead and alive sandflies were performed after each exposure to treated and untreated dogs. Dead sandflies were also counted 24 h after exposure. In Exp. A, the repellency induced by an administration of 30 mg/kg of permethrin to dogs was above 91% for the first two weeks and then dropped to 82.2, 83.1 and 81.1% on Days 14, 21 and 28, respectively. For dogs receiving 60 mg/kg of permethrin, the repellency was a bit higher with 95.8, 97.6, 92.1, 91.4, and 86.8%, for Days 1, 7, 14, 21 and 28, respectively. The repellency induced by 120 mg/kg of permethrin was significantly higher than that induced by 60 mg/kg of permethrin on Day 14 only. In Exp. B the anti-feeding effect of the spot-on formulation was 94.1, 97.8, 96.3, 90.8 and 87% on Days 1, 7, 14, 21 and 28, respectively. The mortality effect was 98.9, 99.1, 99.8, 97.0 and 89.7% on Days 1, 7, 14, 21 and 28, respectively. At each challenge point, the mortality and anti-feeding effects on sandflies were significantly different between control and treatment group ( p