Abstract
To examine the prophylactic efficacy of milbemycin D against Dirofilaria immitis infection, 59 filaria-free beagles were inoculated with 50 to 100 infective larvae of the parasite. Milbemycin D was administered orally at ranges from 0.05 to 3.2 mg/kg of body weight one month after inoculation or at the rate of 1 mg/kg of body weight one to 90 days after inoculation. All dogs were sacrificed for autopsy 6 months after inoculation to confirm the establishment of D.immtis infection. Complete protection from the infection was observed by treating with a dose of 1 mg/kg or more of milbemycin D one or two months after infection.
