Nematocidal efficacy of eprinomectin, delivered topically, in naturally infected cattle

Abstract

Abstract Objective To assess the nematocidal efficacy of eprinomectin in naturally infected cattle. Animals 62 (31 eprinomectin-treated and 31 control) beef mixed-breed or Holstein cattle, either 6 to 11 or 48 to 96 months old. Procedure Cattle were housed 21 to 27 days before treatment to allow parasites to reach maturity. Animals were grouped by sex, ranked by weight, and randomly assigned to treatment group. Fecal flotation was done to identify cattle with intestinal nematode infections. Treatment groups were: 1—eprinomectin topical vehicle (1 ml/10 kg) and 2—eprinomectin topical solution (1 ml/10 kg). Cattle were euthanatized by replicate on day 14 or 15, and standard procedures were used to recover of pulmonary, abomasal, small intestinal, and large intestinal nematodes. Results Eprinomectin efficacy across all trials was 100% against adult Trichostrongylus axei, Haemonchus placei, Oesophagostomum radiatum, and Dictyocaulus viviparus, as well as fourth-stage larval Oes radiatum, Ostertagia ostertagi, Nematodirus helvetianus, and Cooperia spp. Efficacy against adult O ostertagi, Cooperia oncophora, C punctata, C surnabada, C spatulata, N helvetianus, Trichuris sp, and Trichuris fourth-stage larvae was 99.9, 99.8, 99.6, 98.9, 98.3, 99.7, 97.8, and 84.3%, respectively. All results were significant (P < 0.01) except those for C spatulata. Adverse reactions were not observed. Conclusion and Clinical Relevance Eprinomectin is a safe and effective nematocide against naturally acquired nematode infections in cattle when administered at a dosage of 500 μg/kg. Milk and meat withholding is not necessary when using this product. (Am J Vet Res 1997;58:612–614)