Prophylactic medication with pyrantel to prevent liver condemnation in pigs naturally exposed to Ascaris infections.

The use of pyrantel tartrate (106 mg/kg of feed) as a continuous feed medication was evaluated in 848 finishing hogs for efficacy in preventing Ascaris suum infections, and in reducing liver fibrosis and liver condemnation at slaughter, associated with A suum infections. Liver condemnations due to Ascaris damage were reduced 100% in all pigs given pyrantel, when compared with condemnation in non-medicated controls. None of the livers from any of the medicated animals was condemned, whereas livers from 101 (21%) of 479 nonmedicated pigs were condemned due to extensive hepatic scarring. Pyrantel medication administered for 62, 45, or 28 to 31 days resulted in reductions of total number of livers lesions at slaughter by 93.4%, 80.5%, and 68.6%, respectively. In nearly all cases, hepatic lesions remaining at slaughter of pigs given pyrantel in the feed were less distinct than were lesions found on livers from nonmedicated pigs.