Update on the prevalence of anthelmintic resistance in gastrointestinal nematodes of sheep in New Zealand

Authors: McKenna PB
Publication: New Zealand Veterinary Journal, Volume 58, Issue 3, pp 172-173, Jun 2010
Publisher: Taylor and Francis

Animal type: Sheep
Subject Terms: Animal remedies/veterinary medicines, Anthelmintics, Nematode, Parasite control, Parasites - internal
Article class: Peer-reviewed correspondence

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Abstract:

Recently, a comparison was made between the prevalence of anthelmintic resistance, determined using faecal egg count reduction tests (FECRT), on randomly selected sheep farms in a systematic national survey (Waghorn et al. 2006) and that derived from similar case material submitted to a veterinary pathology laboratory on a more ad-hoc basis (McKenna 2008). The results of that comparison showed that while there were some differences between them, there were considerable similarities in the prevalence figures obtained from either source. Those similarities, which were particularly evident in terms of the overall pattern of involvement of the various worm genera and the types of anthelmintic concerned, led to the conclusion that FECRT case submissions to veterinary laboratories may offer a useful source of information regarding changes in the prevalence of anthelmintic-resistant sheep nematodes in New Zealand (McKenna 2008). Accordingly, the present study was undertaken to make further use of this material, to try to ascertain what, if any, such changes may have taken place over the last few years. The study was based on a comparison of case submissions to Gribbles Veterinary Laboratory, Palmerston North, New Zealand, for fully differentiated FECRT in sheep between 2004 and 2006 and 2007 and 2009. Only those cases involving ≥10 animals per treatment group with arithmetic mean pre-treatment strongylid (excluding Nematodirus spp.) faecal nematode egg counts (FEC) of at least 150 epg were included….continued

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