Detection of benzimidazole resistant Nematodirus spathiger

Authors: Chalmers K
Publication: New Zealand Veterinary Journal, Volume 33, Issue 4, pp 53, Apr 1985
Publisher: Taylor and Francis

Animal type: Livestock, Production animal, Ruminant, Sheep
Subject Terms: Alimentary system/gastroenterology, Animal remedies/veterinary medicines, Anthelmintics, Parasite control, Parasites - internal, Nematode, Treatment/therapy
Article class: Correspondence

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Abstract: Benzimidazole (Bz) resistant Nematodirus spathiger were first recorded in New Zealand in 1983. Preliminary investigations are usually based on egg counts when anthelmintic resistance is suspected. Nematodirus sp. lay small numbers of eggs when compared with other nematode genera and there is a poor correlation between egg counts and worm counts in young sheep. Perusal of data relative to further suspected resistance cases suggested a greater disparity between Bz resistant N.spathiger egg and adult worm counts in the autumn than that associated with Bz susceptible N.spathiger. An investigation was completed in April 1984 in which eightmonth-old lambs, naturally infected with known Bz resistant N.spathiger, were egg counted and slaughtered. Worm counts were completed. The results indicate a greater disparity between egg counts and adult work counts in the…

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