Efficacy of topically administered doramectin against eyeworms, lungworms, and gastrointestinal nematodes of cattle

Abstract

Abstract Objective To evaluate efficacy of topically administered doramectin against eyeworms, lungworms, and gastrointestinal nematodes of cattle. Animals 400 cattle (20 cattle in each of 20 trials). Procedure Trials were conducted in North America; natural and experimentally induced infections were used. In each trial, cattle were allocated randomly to control (placebo [saline {0.9% NaCl} solution at 1 ml/10 kg of body weight] or untreated; n = 10) or doramectin-treated (500 µg/kg of body weight; 10) groups. Treatments were applied in a single passage along the midline of the back, from the withers to the tailhead. Cattle were euthanatized ≥ 14 days after treatment, and worm burdens were determined by use of standard techniques. Results Efficacy of doramectin was ≥ 95.3% against adults of Thelazia gulosa, T skrjabini, Dictyocaulus viviparus, Haemonchus contortus, H placei, Ostertagia lyrata, O ostertagi, Trichostrongylus axei, Bunostomum phlebotomum, Capillaria spp, Cooperia oncophora, C pectinata, C punctata, C spatulata, C surnabada, Nematodirus spathiger, Strongyloides papillosus, T colubriformis, Oesophagostomum radiatum, and Trichuris spp. Efficacy was 95.1 % against fourth-stage larvae of D viviparus, H placei, O lyrata, O ostertagi, T axei, C oncophora, C punctata, C spatulata, C surnabada, N helvetianus, T colubriformis, O radiatum, and Trichuris spp. In addition, efficacy against inhibited fourth-stage larvae of O ostertagi and Ostertagia spp was ≥ 98.1 %. Conclusions and Clinical Relevance A single topical application of doramectin pour-on was efficacious against a broad range of nematode species in cattle. (Am J Vet Res 1999;60:665–668)