Efficacy of a Single Oral Administration of Afoxolaner Alone or in Combination with Milbemycin Oxime against Ixodes hexagonus Ticks in Dogs

The efficacy of afoxolaner (NexGard® and NexGard Spectra®, Boehringer-Ingelheim), administered once orally at the minimum recommended dose, was assessed in dogs experimentally infested with Ixodes hexagonus ticks. The study was a blinded, negative controlled clinical efficacy study using a randomized block design. Twenty-four Beagle dogs, 12 females and 12 males were enrolled. Dogs were randomly allocated either to the negative control group, or to one of the two treated groups. Infestations were performed with 50 adult I. hexagonus ticks on Days-2, 7 and 28. On Day 0, dogs in groups 2 and 3 were treated with NexGard® (afoxolaner) or NexGard Spectra® (afoxolaner + milbemycin oxime), respectively. Tick counts were conducted 48 hours after treatment (Day 2) and 48 hours after each subsequent infestation (Days 9 and 30). In both treated groups, afoxolaner was 100% effective against existing infestations (p < 0.0001). Regarding the re-infestations, the efficacy of afoxolaner was 100% on Day 9 for both products, 96.5% and 100% on Day 30 for NexGard® and NexGard Spectra® respectively. NexGard® and NexGard Spectra® chewable tablets administered once orally at the minimum recommended dose were highly effective against I. hexagonus infestations for the 4 weeks duration of the study.