EVALUATION OF THE EFFICACY OF DORAMECTIN AGAINST AN ARTIFICIAL INFECTION OF DICTYOCAULUS-VIVIPARUS IN CALVES

Three groups of eight Friesian calves, reared parasite-free, were expe rimentally infected with 1000 infective larvae of Dictyocaulus vivipar us. Two groups were injected subcutaneously with 1% doramectin at 0.2 mg/kg body weight, one group 5 days after infection and the other 25 d ays after infection. A third group served as untreated controls. Faeca l samples were examined for lungworm larvae on days 28, 32, 33, 34 and 35 after infection; the calves were killed and necropsied 39 or 40 da ys after infection and any lungworms present recovered and counted. Do ramectin proved 100% effective against both 5-day-old and mature D. vi vipharus infections.