Prophylactic Efficacy of Ivermectin against Heartworm in Dogs with Naturally Acquired Infections for two Years

A total of 63 dogs kept outdoors were subjected to study the prophylactic effect of ivermectin against heartworm infections. They were medicated with ivermectin from July through December of 1984 and were negative for microfilariae. Each dog was given 6-9μg/kg of ivermectin orally once a month over a period from July 1985 to December 1985. All the dogs examined in May or June 1986 were negative for microfilariae. No side effects of ivermectin were found.