How well Simparica chewables kill Asian longhorned ticks on dogs

Abstract

BACKGROUND: Haemaphysalis longicornis (Asian longhorned tick) is an invasive species now established in the Northeastern and Mid-Atlantic USA. It feeds on mammalian wildlife, livestock, birds, cats, dogs, and humans. Simparicaand Simparica Triocontain sarolaner, a drug in the isoxazoline class, with activity against fleas, ticks, and mites. METHODS: Two laboratory studies were conducted using 30 dogs each, randomized into three groups (n = 10/group): placebo (Pet Tabs), Simparica Trio (minimum dose: 1.2 mg/kg sarolaner, 24 µg/kg moxidectin, 5 mg/kg pyrantel, as pamoate salt), and Simparica (minimum dose: 2.0 mg/kg sarolaner). Treatments were administered once orally on Day 0 according to the approved commercial dosing directions. Each dog was infested with 50 (± 5) unfed viable adult female H. longicornis on Days -2, 7, 14, 21, 30, 37, 49, and 63, and ticks were counted with removal and categorization at 48 h after treatment and each subsequent infestation. Ectoparasitic efficacy was calculated on the basis of the reduction in arithmetic mean of live and dead tick counts in each of the treated groups versus the untreated control group for every time point post infestation. RESULTS: Adequate challenge was demonstrated in both studies on the basis of live tick counts at each time point. For all sarolaner-treated groups, mean live counts were significantly (P ≤ 0.0005) lower than those for the placebo at all time points. For Simparica, in Study 1, the percentage reductions were 100% for all time points up to Day 39. On Days 51 and 65, the percentage reductions were 98.9% and 82.4%, respectively. In Study 2, reductions were 99.7-100% up to Day 65. For Simparica Trio, in Study 1, percentage reductions were 100% up to Day 51. On Day 65, the percentage reduction was 78.4%. In Study 2, reductions were 99.6-100% up to Day 39 and 97.6% and 94.1% on Days 51 and 65, respectively. CONCLUSIONS: Results from these controlled studies demonstrated high efficacy (78.4-100%) of Simparica and Simparica Trio in reducing existing and subsequent infestations of H. longicornis within 48 h for up to 65 days post treatment.