Prevalence of anthelmintic resistance on sheep and goat farms in the mid-Atlantic region and comparison of in vivo and in vitro detection methods

•Anthelmintic resistance in gastrointestinal nematodes of small ruminants (particularly H. contortus) is a common and important problem in the mid-Atlantic region.•Eighty two percent of all farms tested in this study had multiple-resistance to at least two different drug classes.•Twelve percent of farms demonstrated total anthelmintic failure, where resistance was detected to all available anthelmintics.•Results obtained from the fecal egg count reduction test and the larval development assay were similar.