Persistent activity of ivermectin topical and moxidectin injection against Ostertagia ostertagi and Dictyocaulus viviparus in calves
Hong, C.; Harris, T.J.; Grimshaw, W.T.; Newcomb, K.M.
Veterinary Record 137(25): 640-641
1995
ISSN/ISBN: 0042-4900 PMID: 8693675 Document Number: 447157
Groups of 6 parasite naive, castrated, male calves were treated with ivermectin 0.5% topical solution (500 micro g/kg) 28 or 14 days before experimental infection, or with moxidectin (200 micro g/kg s.c.) on day 28, 14 or 7 before experimental infection, or kept as untreated controls. Each calf was infected orally with 30 000 O. ostertagia and 1000 D. viviparus larvae and slaughtered 24 days after infection; the carcasses were examined for recovery and enumeration of the helminths. Geometric mean worm burdens and efficacy of the treatments were calculated. Topical ivermectin treatment gave complete protection against D. viviparus for at least 28 days and the efficacy against O. ostertagi at 28 days after treatment was > 99%. For moxidectin efficacy was 86% against O. ostertagi and 99% against D. viviparus at 28 days after treatment. The results can be used to design strategic control programmes for optimum parasite control with minimum use of endectocides.