Ivermectin as an antiparasitic agent in cattle.

In experimental trials on cattle, ivermectin given SC at 200 micrograms/kg had 95% or better efficacy against adult and immature GI and pulmonary nematodes, including inhibited fourth-stage larvae of Ostertagia ostertagi. Studies of efficacy against ectoparasites revealed nearly 100% efficacy against sucking lice, psoroptic and sarcoptic mange mites and cattle grubs. Safety trials revealed no adverse effects with the recommended dosage, including bulls and pregnant cows. A few grub-infested cattle died from acute esophagitis associated with a host-parasite reaction after ivermectin injection.