Efficacy of orally administered fluralaner in dogs against laboratory challenge with Haemaphysalis longicornis ticks

BACKGROUND: Haemaphysalis longicornis ticks represent an ectoparasitic health threat to dogs. This study evaluated the immediate and persistent efficacy of orally administered fluralaner for control of this tick. METHODS: Twenty-four dogs were sorted into 4 groups based on their tick carrying capacity measured in a preliminary challenge. Two days before treatment, dogs were challenged with Haemaphysalis longicornis and then at the time of treatment dogs received with oral fluralaner at 10, 25 or 50 mg/kg respectively to 3 of the groups, while the remaining group was sham treated. Ticks were counted and categorized on all dogs 2 days after treatment (4 days after challenge). Tick challenges were repeated at 28, 56, 84 and 112 days following treatment with tick counts 48 hours following each challenge. Tick control efficacy was evaluated by comparing the mean (geometric) total live attached and dead engorged ticks on each fluralaner treated group with the sham treated dogs. RESULTS: Oral fluralaner is highly acaricidal for H. longicornis that feed on treated dogs. The mean efficacy rate in dogs treated with fluralaner at the commercial dose range of 25 to 50 mg/kg was greater than 90% at 114 days after treatment, whereas efficacy at this time in dogs treated at 10 mg/kg was 79%. CONCLUSIONS: Fluralaner administered orally to dogs within the commercial dose range at 25 to 50 mg/kg is effective for up to 114 days against laboratory challenge with H. longicornis ticks.