ANTHELMINTIC TREATMENT AND THE SUPPRESSION OF EGG-PRODUCTION IN GASTROINTESTINAL NEMATODES OF SHEEP AND CATTLE - FACT OR FALLACY

Evidence for a temporary suppression of egg production in gastro-intes tinal nematodes of sheep and cattle following anthelmintic treatment i s reviewed and the possible relevance of this phenomenon to the approp riate sampling time in the faecal egg count reduction test is discusse d. The results of this review suggest that if such suppressive effects do occur in sheep nematodes, then they are unlikely to be of much pra ctical significance and that little benefit would be derived from exte nding the post-treatment sampling interval beyond IO days. For cattle nematodes, however, the issues are less readily obvious but indicate, at least when testing for resistance to persistent anthelmintics, that adoption of a longer post-treatment interval might be advisable.