title: The occurrence of anthelmintic-resistant sheep nematodes in the southern North Island of New Zealand.
abstract: An analysis of veterinary diagnostic cases submitted to the Batchelar Animal Health Laboratory for faecal egg count reduction testing in sheep between 1986 and 1992 showed that 63% of them originated from properties carrying anthelmintic-resistant worms. Most of these cases involved resistance to a single drench type only, with the benzimidazoles being implicated most frequently. Overall, the figures suggested a frequency of occurrence of resistance to benzimidazole anthelmintics of 74%, to levamisole-type anthelmintics of 23% and to benzimidazo-lelevamisole combinations of 30%. No cases of resistance to milbemycin/avermectin-type drenches were recorded.
authors: Batchelar Animal Health Laboratory, P.O. Box 536, Palmerston North, New Zealand.
authors: P B
authors: PB
authors: McKenna