Activity of pyrantel against Parascaris equorum

Anthelmintic resistance in equine nematodes

“…In terms of the 95% LCL selected for classifying resistance, this varied depending on the class of anthelmintic tested with the percentage reduction threshold used for classifying resistance to macrocyclic lactones set at 90% and, for benzimidazoles and tetrahydropyrimidines, 80%. These cut-offs have been selected to reflect original efficacy levels reported in anthelmintic-sensitive strongyle populations soon after the products were registered for use in horses ( Cornwell and Jones, 1969; Colglazier et al, 1977; Xiao et al, 1994 ). Maximum likelihood models, based on the negative binomial distribution for estimating FEC reduction ( Torgerson et al, 2005 ), and Markov Chain Monte Carlo methods ( Denwood et al, 2010 ) have also been suggested to account for the highly aggregated distribution inherent in equine FEC data.…”