Anthelmintic activity of ivermectin in pigs naturally infected with Ascaris and Trichuris.

The anthelmintic efficacy of ivermectin administered by subcutaneous (SC) injection or orally via the drinking water was investigated in feeder pigs naturally infected with Ascaris suum and Trichuris suis. Group 1 pigs (n = 5) were given drinking water as a placebo, group 2 pigs (n = 5) were given ivermectin by SC injection (300 micrograms/kg of body weight), and group 3 pigs (n = 5) were given ivermectin in water also at a dosage rate of 300 micrograms/kg of body weight. At necropsy 11 days later, the mean worm counts in group 1 pigs were 4 for Ascaris and 50.2 for Trichuris. All adult and juvenile ascarids were removed from the intestine in groups 2 and 3 pigs. Compared with the number of Trichuris in group 1 pigs, the number of Trichuris was reduced by 91.2% and 78.1%, respectively, for the orally and SC treated pigs.