Efficacy of two topical fluralaner formulations (Bravecto® ; Bravecto® Plus) against Asian longhorned tick (Haemaphysalis longicornis) infestations of cats

Abstract

Background The invasive tick species, Haemaphysalis longicornis, is becoming established in the United States, presenting a growing threat to dogs and cats. Two 90-day studies were initiated, the same protocol in each, to confirm the efficacy of a single application of two fluralaner formulations against H. longicornis infestations of cats. Methods Cats were randomized between three groups in a 1:1:1 ratio (10 cats/group). Group 1 cats were untreated controls; Group 2 cats were treated with a topical fluralaner formulation (Bravecto®); Group 3 cats received a topical formulation containing fluralaner and moxidectin (Bravecto® Plus). Treatments were administered once (Day 0) at the label dose rates. Each cat was infested with 50 H. longicornis on Day − 7 for study qualification, and Days − 2, 28, 58, and 88. Tick counts were completed on Days − 5, 2, 30, 60 and 90. To allow between-group comparisons at any assessment, at least six Group 1 cats were required to retain at least 25% of the infestation dose. The primary objective was based on percentage reductions in arithmetic mean tick counts. Results Pre-study infestations showed all study cats were susceptible to tick challenge. Except for Day 2 in one study, at least six control cats retained ≥ 25% of each challenge, demonstrating an adequate infestation for efficacy assessments. Across studies on Days 2, 30, 60 and 90, the mean live tick infestation rate (number of ticks recovered from each cat/infesting challenge to each cat) of Group 1 cats ranged from 25.0 to 69.6%. Efficacy of each formulation, based on live tick counts, was 100% on Day 2 and > 95 to 100% at each subsequent assessment. Between-group differences were statistically significant (P < 0.0001) for each treatment versus control comparison. Conclusion At the label dose rate, both topical fluralaner formulations were 100% effective in eliminating H. longicornis ticks from cats infested at the time of treatment. Efficacy of > 95 to 100% was then maintained through 90 days following a single application. Fluralaner is therefore a treatment of choice for protecting cats against this invasive tick species.