Abstract
Extract
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. Citation2006) and that derived from similar case material submitted to a veterinary pathology laboratory on a more ad-hoc basis (McKenna Citation2008). 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 anthelminticresistant sheep nematodes in New Zealand (McKenna Citation2008). 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.