Ovicidal action of oxfendazole on sheep nematodes.

Groups of five sheep naturally infested with gastrointestinal nematodes were dosed with oxfendazole at the rates of 2.5, 3.5, or 4.5 mg per kg and a similar group of five kept as controls. Frequent observations were made on worm egg output and the hatchability of the eggs passed. The first ovicidal activity was apparent five hours after treatment. Within eight hours 99.7 per cent or more of the eggs voided were sterile and by 30 hours there was a 99.9 per cent reduction in the numbers of larvae hatching compared with the controls. Within three days of dosing the faeces of the treated sheep were negative for worm eggs.