Persistent efficacy of long-acting moxidectin for control of trichostrongylid infections of sheep

Abstract

The objective was to evaluate long-acting moxidectin (Cydectin (R) 2% LA for sheep) against trichostrongylids in sheep. We performed a blocked, parallel, controlled clinical trial. We included 45 ewe-lambs, allocated into treated (n=30, 1.0 mg moxidectin per kg bw, subcutaneously at base of ear on D 0) or controls (n=15). Animals had been naturally infected (pre-treatment geometric mean epg counts: 233 and 249, respectively) and throughout the study grazed at the same pasture. Fortnightly, we collected faecal samples and performed established parasitological techniques (epg counts, coprocultures). We used analysis of covariance for post-treatment results, using pre-treatment counts as covariate, treatment as fixed effect, block as random effect. Geometric mean epg counts in treated animals were 0 up to D 112, 1 on D 126, 4 on D 140 and 13 on D 161. Respective figures for controls were 369-820 tip to D 140 and 168 on D 161 (p<0.05). Persistent efficacy (>90%) was 140d for Teladorsagia, 119 d for Haemonchus and 115 d for Trichostrongylus. This is the first reported clinical trial of efficacy of long-acting moxidectin in sheep in Europe. Cydectin 2% LA was found to be effective against trichostrongylids of sheep. The particularly long persistent efficacy can provide new possibilities in formulating anthelmintic programs for sheep. (C) 2008 Elsevier B.V. All rights reserved.