Efficacy of a novel oral formulation of sarolaner (Simparica™) against four common tick species infesting dogs in Europe

The efficacy of single oral treatment of sarolaner (Simparica (TM), Zoetis), a novel isoxazoline compound, was evaluated against four tick species known to commonly infest dogs in Europe. Eight laboratory studies were conducted using adult purpose-bred Beagle dogs. In each study, 16 animals were randomly allocated to one of two treatment groups based on pre-treatment host-suitability tick counts. Dogs were infested with 50 unfed adult Dermacentor reticulatus (two studies), Ixodes hexagonus (three studies), Ixodes ricinus (two studies) or Rhipicephalus sanguineus (one study) ticks on Days 2, 5, 12, 19, 26 and 33. On Day 0, dogs were treated orally with placebo or sarolaner tablets providing the minimum dose of 2.0 mg/kg bodyweight and tick counts were conducted 48 h after treatment and after each subsequent weekly re-infestation. There were no treatment-related adverse reactions in any of the studies. Dogs in the placebo-treated group maintained tick infestations throughout the studies. Geometric mean live tick counts were significantly (P <= 0.0001) lower in the sarolaner-treated group compared to the tick counts in the placebo group at all time-points. A single oral administration of sarolaner resulted in 100% efficacy against existing infestations of all tick species except R. sanguineus, for which the efficacy was 99.7%, within 48 h. Efficacy against weekly re-infestations was >= 97.5% for all tick species for 35 days. Thus, a single dose of sarolaner administered orally at the minimum dosage of 2 mg/kg, resulted in >= 99.7% efficacy within 48 h against existing tick infestations, and in >= 97.5% efficacy against weekly re infestations, for at least 35 days after treatment. These studies confirmed that administration of the minimum dose of sarolaner will provide treatment of existing infestations and give at least one month of control against re-infestation by the common tick species affecting dogs in Europe. (C) 2016 The Authors. Published by Elsevier B.V.