Abstract
The persistent anthelmintic effect of ivermectin as a topical treatment at 500 µg/kg was evaluated against induced infections of Ostertagia ostertagi, Trichostrongylus axei and Dictyocaulus vivparus in calves. The results showed a highly significant (P99 per cent efftcacies) and for at least 28 days (98 per cent efficacy) against D. viviparus.