Abstract
Extract
Anthelmintic resistance in gastrointestinal nematode parasites of sheep and goats is usually detected in the field by means of the faecal egg count reduction (FECR) testCitation (1) Citation (2) Citation (3) . However, a recent publication in this journalCitation (4) has raised some doubts regarding the appropriateness of this procedure for detecting resistance to ivermectin by suggesting that treatment with this drug may affect the fecundity of surviving worms. Little evidence was provided to support this suggestion by, for example, counting eggs in uteri and, in my opinion, such concerns are neither justified by the results of this study, nor warranted by the weight of other existing evidence.