Field Trial of Monthly Ivermectin Administration for the Prevention of Dirofilaria immitis infection in Dogs

The prophylactic efficacy against Dirofilaria immitis infection by monthly ivermectin asdministration was tested in a practice. One hundred and thirty-two uninfected dogs were used in this study. 88 dogs were dosed with 6 to 9μg/kg of ivermectin each month from the beginning of July until December in 1984. 44 dogs were kept as controls. All of them were examinated for microfilariae in the blood with either acetone concentration or filter techniques during May to June in 1985.The prophylactic efficacy of ivermectin was 100%. The control dogs showed a 34.1% infection rate. There were no abnormal findings in any of the treated dogs during the experimental period.