PROPHYLACTIC USE OF IVERMECTIN AGAINST CATTLE MYIASIS CAUSED BY COCHLIOMYIA-HOMINIVORAX (COQUEREL-1858)

The prophylactic efficacy of ivermectin against navel or scrotal myias is in calves was evaluated in eight trials in Argentina and Brazil. In two trials, calves were injected subcutaneously with ivermectin at a dosage of at least 200 mu gkg(-1) within 24 h of birth. In the other s ix trials, two with two-month-old calves and four with four-month-old or older calves, all calves were treated with ivermectin at a dosage o f at least 200 mu gkg(-1) immediately after castration. In all trials, calves were maintained together on pasture and naturally exposed to C ochliomyia hominiuornr. Navel and scrotal wounds were examined for myi asis daily for at least 14 days. Incidence of navel and scrotal myiasi s was significantly lower (P < 0.01) in treated calves than in control calves. (C) 1997 Elsevier Science B.V.