Activity against Ostertagia ostertagi of low doses of oxfendazole continuously released from intraruminal capsules in cattle.

Slow release from intraruminal capsules of 0.48 mg/kg oxfendazole per day for 5.5 days gave percentage efficiencies of 99 +/- 0.6, 86.6 +/- 6.3 and 93.1 +/- 4.5 for the removal of adult worms, developing 4th stages and inhibited larvae of Ostertagia ostertagi respectively. These efficiencies were not significantly different from those obtained from a single oral dose of 2.5 mg/kg. Peak plasma levels of oxfendazole were similar for the 2 types of administration but high levels were maintained longer in cattle given capsules.