Similar patterns of benzimidazole resistance alleles suggest shared origins of resistance for ovine gastrointestinal nematodes from western Canada and the eastern United States

We have undertaken a large scale study to compare the frequency and distribution of benzimidazole mutations and alleles in the major ovine gastrointestinal nematode species in two large regions of North America; western Canada and eastern United Stated. Deep amplicon sequencing was used to screen for isotype-1 B-tubulin benzimidazole resistance mutations in 102 and 28 sheep flocks from Western Canada and the eastern USA respectively for the three most common gastrointestinal nematode (GIN) species; Haemonchus contortus, Trichostrongylus colubriformis and Teladorsagia circumcincta.