Anthelmintic resistance in Northern Ireland (II): Variations in nematode control practices between lowland and upland sheep flocks

Evidence for reversion towards anthelmintic susceptibility in Teladorsagia circumcincta in response to resistance management programmes

“…Also, it was considered that by not exposing individual worms to more than one class of anthelmintic, selection for resistance to multiple actives was less likely to occur ( Prichard et al., 1980 ). The practice of rotating different anthelmintic classes annually was widely adopted in some countries ( Kettle et al., 1983; Waller et al., 1989; Lawrence et al., 2007; Sargison et al., 2007 ) and is still promoted today in some countries and classes of animals ( McMahon et al., 2013a ). However, in the interim resistance has continued to develop and resistance to multiple anthelmintic classes is now well established on some farms ( van Wyk et al., 1997; Waghorn et al., 2006; Le Jambre et al., 2010; Torres-Acosta et al., 2012; McMahon et al., 2013b; Geurden et al., 2014 ).…”

Potential impacts of climate change on veterinary medicinal residues in livestock produce: An island of Ireland perspective††This paper is one of a series of reviews on “Climate Change and Food Safety – an Island of Ireland perspective”.

“…However, a number of practices which are selective for anthelmintic resistance are still commonly used in NI. These include using unchecked dosing equipment, co-grazing sheep and cattle, always using the same anthelmintic product and a decreasing contribution to the in refugia population by lambs (McMahon et al, 2013b).…”

“…3). This gap has largely been filled by closantel, either as a single active or in combination with ivermectin, its use increasing from 22% by 2005 to 56% by 2011 (McMahon et al, 2013b). Closantel's popularity is demonstrated by it being the most common anthelmintic residue detected in a survey of beef purchased in ROI in 2009(Cooper et al, 2012.…”

“…Already there have been large-scale shifts in product use (Fig. 3) and changes in treatment timing (McMahon et al, 2013b;unpublished observations). These changes in timing are linked to the withdrawal periods of products, the perception of resistance, the spectra of activity of the products and the altered seasonal appearance of parasites ( Figs.…”

Control of Nematodirus spp. infection by sheep flock owners in Northern Ireland

“…A coprological survey carried out in July–October 2011 provided information on the prevalence of AR in gastrointestinal nematode infections in sheep [ 7 ]. A Questionnaire survey (conducted between May–September 2011) examined patterns of anthelmintic drug use and the effectiveness of management strategies in place to control the diseases [ 8 , 9 ]. However, the timing of the coprological survey in 2011 precluded the collection of data in relation to Nematodirus spp.…”