Prophylactic efficacy of milbemycin oxime against multiple infection of dogs with Dirofilaria immitis.

In order to examine the prophylactic effects of milbemycin oxime (MO) against Dirofilaria immitis infection, experiments were carried out under multiple infection with D. immitis. Ten filaria-free beagles of age 4 to 8 months were each inoculated with a total number of 480 larvae 12 times at intervals of 15 days over a period of 6 months, and MO was given monthly for the 6 months at a dose of 0.25 mg/kg. The infection rate in the medicated group of dogs was nil, this suggesting complete protection of the infection, while in the non-medicated control group it ranged from 6.5 to 14.8% (mean, 11.4%).