Further studies on the necessity or otherwise of multiple pre-treatment groups in faecal egg count reduction tests in sheep.

Data utilised in a previous study to compare two different faecal egg count reduction tests (FECRTs) in sheep involving multiple anthelmintic treatments and undifferentiated faecal egg counts (FECs), were re-examined using FECs for individual parasite genera. The first of these FECRTs was based on changes in the pre- and post-treatment FECs of the same groups of animals. The other represented an abbreviated version of the former procedure and involved only a single common pre-treatment group as a baseline for comparing all post-treatment results. A comparison of the results obtained with these two procedures showed that the use of either one of them was likely to provide similar estimates of anthelmintic efficacy and the detection of a comparable number of cases of anthelmintic-resistance for all parasite genera. These findings offer further support to a previously expressed view that the use of the more complex and costly pre- and post-treatment FECRT procedure is unlikely to provide any real advantages over the simpler one.