Dermal safety study with imidacloprid/moxidectin topical solution in the ivermectin-sensitive collie

A study was conducted to determine the safety of the dermal application of 10% imidacloprid/2.5% moxidectin topical solution in ivermectin-sensitive collies. Each milliliter of this solution contains 100 mg of imidacloprid and 25 mg of moxidectin. A total of 21 collies were prescreened for ivermectin-sensitivity and heartworm negative status prior to selection for the study. Animals were assigned based on the maximum ivermectin-sensitivity score demonstrated during the prestudy screening. Treatment groups included a 3× and 5× test article group, and a 3× and 5× mineral oil control group. The 3× and 5× doses were administered at three and five times, respectively, the 1× dose based on the animal's body weight. On day 0, 3 of the 21 dogs were treated with dermal applications of a preliminary dose of 3× test article to screen for unexpected signs of toxicity with the remaining 18 dogs being treated with 3× mineral oil to blind for the volume of liquid applied. After no signs of toxicity were observed, these same three dogs were treated with 3× of test article and 2× mineral oil on days 28 and 56. The remaining 18 animals were equally allocated to either a 5× test article group or a 5× control group and were each treated on days 28, 56, and 84. Personnel performing observations were blinded to treatment. Observations were made for clinical signs of ivermectin sensitivity twice daily during non-dosing days. On treatment days, dogs were observed hourly for the first 4 h post-treatment and at 6, 8, 12, 18 and 24 h. Signs of toxicosis were not observed in any of the dogs throughout the observation period. This study demonstrated the safety of imidacloprid/ moxidectin, when administered to collies testing positive for ivermectin sensitivity at dosages up to five times the maximum recommended dose.