Evaluation of the effectiveness of a novel oral formulation of sarolaner (Simparica™) for the treatment and control of fleas on dogs

• Oral sarolaner is effective for treatment and month-long control of fleas on dogs.
• Efficacy against cat fleas was ≥99.8% within 24 h of treatment.
• Control of weekly re-infestations was ≥99.8% for at least 35 days after dosing.
• Equivalent efficacy was confirmed against the dog flea.
• Efficacy was 100% for 35 days versus the KS1 (insecticide-tolerant) cat flea.

The efficacy of a single oral dose of a novel isoxazoline, sarolaner (Simparica™, Zoetis), for the treatment and control of flea infestations on dogs was confirmed in five laboratory studies. The studies were conducted using adult purpose-bred Beagles and/or mixed breed dogs. All animals were individually identified and housed, and were allocated randomly to treatment with either placebo or sarolaner (eight to 10 per group) based on pretreatment parasite counts. Three studies used cat flea (Ctenocephalides felis felis) strains recently isolated from the field from the US, EU, or Australia; in the fourth study a laboratory strain (KS1) with documented tolerance to a number of insecticides such as fipronil, imidacloprid, and permethrin was used. In the fifth study, dogs were infested with dog fleas, Ctenocephalides canis. Dogs were treated orally on Day 0 with a placebo or a sarolaner tablet providing a minimum dose of 2 mg/kg. Dogs were infested with approximately 100 unfed, adult fleas prior to treatment and at weekly intervals post-treatment. Comb counts were conducted to determine the numbers of viable fleas at 24 h after treatment and after each subsequent infestation. Efficacy against C. felis and C. canis was 99.8–100% from treatment through Day 35. In all five studies, elimination of existing infestations was achieved within 24 h after dosing, with only a single live C. felis found on one dog on Day 1. Similarly, control of flea challenges was achieved within 24 h after infestation throughout the 35 day study periods, with only single live C. felis found on two dogs on Day 28 in one study, and on a single dog on Day 35 in another study. There were no adverse reactions to treatment with sarolaner. These studies confirmed that a single oral dose of sarolaner at 2 mg/kg provided highly effective treatment of existing C. felis infestations and persistent control of C. felis on dogs for 35 days after treatment. Efficacy equivalent to that seen with C. felis was confirmed against C. canis and a known insecticide-tolerant strain of C. felis.