Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
8991269 | Veterinary Parasitology | 2005 | 7 Pages |
Abstract
The efficacy of a commercial pour-on formulation of eprinomectin, a macrocyclic lactone, against experimental infestations of Boophilus microplus (Canestrini) ticks was evaluated in two trials involving 27 Bos taurus calves. The first trial was designed to evaluate the effects of a single treatment at a dose of 0.5Â mg/kg of body weight against standard size B. microplus females (4.5-8.0Â mm long). A significant reduction in tick numbers (PÂ <Â 0.05, Wilcoxon test) was observed between treated calves as compared to untreated ones from Day 3 (44% efficacy) after treatment to the end of the trial on Day 28 (96.9%), with a peak efficacy of 97.1% on Day 21. In the second trial the effect of eprinomectin on standard size tick numbers, engorgement weight and fertility of female ticks from calves with a single treatment dose of 1Â mg/kg on Day 0 and calves treated twice at a dose of 0.5Â mg/kg on Days 0 and 4 was evaluated. An efficacy >93% was obtained from Day 2 to Day 28 after treatment in calves treated twice at 0.5Â mg/kg, and to the end of the trial (Day 35) in calves treated once with 1Â mg/kg. The 1Â mg/kg treatment provided >98% residual efficacy for at least 7 days. During the first part of the second trial the efficacy of eprinomectin resulted from a dramatic adverse effect on engorgement weight and fertility of female ticks, with 100% control on Day 5 (dosage of 1Â mg/kg) and on Days 6 and 7 (two doses of 0.5Â mg/kg). Following Day 7, most of the effect was due to reduction in the number of standard size female ticks.
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Authors
D.H. Aguirre, A.B. Gaido, M.M. Cafrune, M.E. Castelli, A.J. Mangold, A.A. Guglielmone,