Efficacy of moxidectin as a 1% injectable solution and a 0.1% oral drench against nasal bots, pulmonary and gastrointestinal nematodes in sheep

Abstract

Thirty ewes, 3–10 years old, known to be naturally infected with internal parasites, were allocated to three homogeneous groups of ten ewes each based on faecal nematode egg counts. The following experimental treatments were administered on Day 0: (A) moxidectin 1% injectable solution at 0.2 mg kg −1 body weight; (B) moxidectin 0.1% oral drench solution at 0.2 mg kg −1 liveweight; (C) untreated control. Faecal samples were taken on Days −7, 0, 1, 2, 3, 7, 14, 21, 28 and 35 to obtain counts of nematode eggs. One-half of the ewes in each treatment group were slaughtered 14 days after dosing, while the remainder were slaughtered 35 days after treatment to count the numbers of nasal bots, pulmonary nematodes and gastrointestinal nematodes. Moxidectin 1% injectable solution and moxidectin 0.1% oral drench solution were highly effective against gastrointestinal nematodes and against a variable infection of Dictyocaulus filiaria. Moxidectin 1% injectable solution was effective against first stage larvae of Oestrus ovis, whereas moxidectin 0.1% oral drench was ineffective.