THE REAPPEARANCE OF STRONGYLE EGGS IN FECES OF HORSES TREATED WITH PYRANTEL EMBONATE

The reappearance of strongyle eggs in the faeces of horses treated wit h pyrantel embonate was studied. The horses (103) were devided in 11 g roups on 8 different farms. The efficacy of pyrantel embonate against strongyles, based on egg count reduction tests, was 99.8%. Mean weekly egg counts performed between week 2 and week 9 after treatment showed that 5 weeks after treatment the egg output passed the 90% reduction level. It is concluded that strategic treatments of horses with pyrant el embonate for the prevention of strongylosis should be administered with intervals of 6 weeks.