Failure of injectable ivermectin to control psoroptic mange in cattle.

摘要

In this study, 8 Belgian Blue cattle naturally infected with Psoroptes ovis served as untreated controls in an experiment which evaluated the efficacy of a commercial drug (Bayticol) on a farm with recurrent psoroptic mange. However, the clinical conditions of these animals deteriorated and 2 were treated with a generic injectable ivermectin formulation at 0.2 mg/kg on day 14 and all were treated on days 28 and 43. Despite a slight reduction of the mean clinical index, 5 animals were still actively infested on day 60, including 1 that had been treated 3 times. Seven cattle also lost weight. These results indicate a resistance to ivermectin by P. ovis.