Anthelmintic resistance has grown from a curiosity to an important economic
problem in several animal industries and is now set to threaten the contro
l of human parasites. The pharmacology of anthelmintics and anthelmintic re
sistance has been studied most extensively in the nematode parasites of she
ep. Here, Nick Sangster and Jenny Gill discuss this veterinary Experience,
summarizing the progress made in understanding anthelmintic resistance and
highlighting the tools available for research.