Evaluation of marked rise in fecal egg output after bithionol administration to horse and its application as a diagnostic marker for equine Anoplocephala perfoliata infection.

To establish a reliable diagnostic measure for equine Anoplocephala perfoliata infection, the impact of deworming was examined in 12 Thoroughbreds to which bithionol (5-10 mg/kg body weight) was administered and feces were examined by the modified Wisconsin method using sucrose solution. One day after the administration, cestode eggs were detected in previously fecal egg-negative 3 horses and increased in the other 9 horses. The optimum time for post-deworming egg detection was examined in following horses: 17 mares were administered bithionol and 10 mares were used as controls. The fecal egg count was significantly (P<0.01) higher one day after the administration than that on other pre- and post-administration days, while no significant changes occurred in fecal egg count in the controls, demonstrating that one day after bithionol administration is the optimum time for detecting fecal cestode eggs. The diagnostic deworming involving bithionol and fecal examination on the day following administration provides a reliable diagnosis for equine Anoplocephala perfoliata infection.