Efficacy of a new topical formulation of selamectin plus sarolaner for the control of fleas and ticks infesting cats in Japan

Abstract The efficacy of a single application of a new topical formulation containing selamectin plus sarolaner (Revolution ® Plus / Stronghold ® Plus, Zoetis) was evaluated against fleas and ticks infesting cats enrolled as veterinary patients in two field studies conducted in Japan and against Haemaphysalis longicornis ticks on cats in a laboratory study. In the laboratory study, sixteen cats were ranked based on pre-treatment tick counts and allocated randomly to treatment on Day 0 with either selamectin plus sarolaner or placebo. Cats were infested with adult H. longicornis on Days −2, 5, 12, 19, 26 and 33. Efficacy relative to placebo was based on live attached tick counts conducted 48 h after treatment and subsequent re-infestations. Selamectin plus sarolaner reduced live, attached H. longicornis counts by 96.4% within 48 h of treatment, and by ≥91.7% within 48 h of weekly re-infestation for 35 days, based on arithmetic means. In the field studies, 67 client-owned cats harboring six or more live fleas and 63 cats harboring four or more live attached ticks were enrolled to evaluate selamectin plus sarolaner for efficacy and safety compared with a registered product. Cats were allocated randomly to treatment with selamectin plus sarolaner or fipronil plus (S)-methoprene based on order of presentation. Treatment was administered once on Day 0 and efficacy was assessed by parasite counts conducted on Days 14 and 30 compared to the pre-treatment count. In the flea field study, live flea counts on Days 14 and 30 were reduced by 99.5% and 99.9% in the selamectin plus sarolaner group, and by 97.6% and 98.6% in the fipronil plus (S)-methoprene group, based on least squares mean percentage reductions. Clinical signs typically associated with flea allergy dermatitis improved following treatment. In the tick field study, live tick counts on Days 14 and 30 were reduced by 97.5% and 97.7% in the selamectin plus sarolaner group, and by 91.5% and 93.4% in the fipronil plus (S)-methoprene group, based on least squares mean percentage reductions. Selamectin plus sarolaner was determined to be non-inferior to fipronil plus (S)-methoprene in both field studies. There were no treatment-related adverse events in any study. A single topical dose of Revolution ® Plus / Stronghold ® Plus providing a minimum dosage of 6.0 mg/kg selamectin and 1.0 mg/kg sarolaner was confirmed to be effective against H. longicornis ticks on cats for one month and safe and effective in the treatment of fleas and ticks on cats enrolled as veterinary patients in Japan.