PERSISTENT EFFICACY OF TOPICAL MOXIDECTIN AGAINST DICTYOCAULUS-VIVIPARUS AND OSTERTAGIA-OSTERTAGI

The persistent activity of moxidectin topically administered at the do se rate of 0.5 mg kg(-1) bodyweight was evaluated against experimental nematode infection in 30 calves randomly allocated to six groups. Fiv e groups were treated on days -42, -35, -28, -21 and -14. The 6th grou p remained untreated as a control. On Day 0, the calves were infected experimentally with 1000 Dictyocaulus viviparus and 50 000 Ostertagia ostertagi larvae and killed 3 weeks later. The formulation of moxidect in showed excellent activity against both parasites for up to 5 weeks (> 99%). Six weeks after treatment the reduction in the number of D. v iviparus was still high (> 90%). No adverse reactions to moxidectin we re observed in any of the animals.