Persistent efficacy of doramectin and moxidectin against Cooperia oncophora infections in cattle

Duplicate studies in France and Northern Ireland were carried out to determ ine the persistent efficacy of topical moxidectin and doramectin against na tural infections of Cooperia oncophora. In each study, groups of 15 nematod e-naive calves were treated either with topical doramectin or moxidectin, a nd put out to graze on pasture contaminated with C. oncophora infective lar vae. The persistent efficacy for preventing establishment of infection was assessed by the time to faecal egg excretion of C. oncophora eggs. It was f ound that the moxidectin treatment prevented infection for less than 10 day s and the effect of doramectin lasted for 24 days. (C) 2001 Elsevier Scienc e B.V. All rights reserved.