Therapeutic and prophylactic efficacy of milbemycin oxime (Interceptor) against Thelazia callipaeda in naturally exposed dogs

Two trials were conducted to evaluate the therapeutic and prophylactic activity of milbemycin oxime (Interceptor, Novartis Animal Health) against the eye-worm Thelazia callipaeda (Spirurida, Thelaziidae) infection. In Trial 1, the therapeutic efficacy of milbemycin oxime was evaluated in 55 naturally infected dogs treated with min. 0.5mg/kg milbemycin oxime. The dogs were clinically examined for the presence of eyeworms before and again 7 days after treatment. Dogs still positive were given a second treatment and re-checked again a week later. Forty-eight of the 55 dogs tested negative 1 week after treatment (87.3% reduction of infection rate). Following the second treatment 6 of these 7 dogs tested negative 1 week later resulting, after two treatments, in a reduction of infection rate of 98.2%. In Trial 2, the prophylactic efficacy of milbemycin oxime was evaluated in 60 uninfected dogs. Thirty dogs were treated with milbemycin oxime monthly from June to November with the recommended dose rate for the prevention of heartworm disease (> or =0.5mg/kg), 30 dogs served as untreated controls. At the end of the trail 1 dog in the treated group and 10 dogs in the control group became infected during the trial. The incidence of infection differed significantly between treated and control dogs (p=0.0056). The efficacy of the prophylactic use of a monthly treatment with milbemycin oxime showed 90% efficacy in reducing T. callipaeda infection rate.