Ruminoreticulum bypass in goats and its possible effect on the efficacy of oxfendazole against resistant gastrointestinal parasites

Abstract Ruminoreticulum bypass was observed in 9–12-month old Angora goats using video-taped fluoroscopy. For experimental purposes, ruminoreticulum bypass was stimulated by yarding animals for 19–24 h before drenching, or by yarding and oral premedication with 2% cobalt sulphate solution. When bypass occurred, 50–100% of the drench was deposited in the abomasum. Ruminoreticulum bypass had no apparent effect on the faecal egg count reduction of benzimidazole resistant Ostertagia spp. following drenching with a standard dose of 5 mg/kg of oxfendazole, although the low frequency of bypass prevented any firm conclusions from being made. The importance of ruminoreticulum bypass to the efficacy of benzimidazole anthelmintics in goats may have been overemphasised.