Abstract
BACKGROUND: Amblyomma maculatum is a tick with a broad host range that is undergoing an expansion of its range within the USA. When feeding the predilection sites on the host are the head and ears and due to the long mouthparts, it can cause significant lesions that can lead to infection. It has also been implicated as a vector of Hepatozoon americanum, the causative agent of canine hepatozoonosis and a spotted fever group Rickettsia, Rickettsia parkeri. METHODS: Two randomized, blinded, negative controlled studies were conducted to determine whether treatment with afoxolaner (NexGard(®), Boehringer Ingelheim) or a combination of afoxolaner, moxidectin, and pyrantel (NexGard(®) Plus, Boehringer Ingelheim) effectively treats and controls infestations of A. maculatum on dogs. For each study, ten healthy dogs were randomly assigned to each treatment group. In one study there were three treatment groups: an untreated control, NexGard(®)-treated group, and NexGard(®) Plus-treated group. The other study had an untreated control group and a NexGard(®) Plus-treated group. Dogs were infested with approximately 50 unfed adult A. maculatum prior to treatment for evaluation of efficacy against existing infestations and then three times after treatment for evaluation of persistent efficacy. In each study the appropriate treatment groups were treated with either NexGard(®) or NexGard(®) Plus with afoxolaner targeted at 2.5 mg/kg, and ten control dogs were untreated. For evaluation of efficacy, live ticks were counted and removed from each dog at 72 h after treatment or subsequent infestations. RESULTS: NexGard(®) and NexGard(®) Plus were > 99% effective against established infestations of A. maculatum compared with the control group (P < 0.0001). NexGard(®) and NexGard(®) Plus were ≥ 92% effective against reinfestation with A. maculatum through Day 31 of the studies (P < 0.0001). CONCLUSIONS: The results of these studies demonstrate that NexGard(®) and NexGard(®) Plus administered once at or near the minimum recommended dose of 2.5 mg/kg afoxolaner is effective for the treatment of existing A. maculatum infestations and for the control of infestations through Day 31.