Evaluation of Anthelmintic Efficacy of Bithionol Paste against Tapeworms Naturally Infected in Horses, by Fecal Examination and Necropsy; A Critical Trial

Abstract

This study was conducted to evaluate the efficacy of bithionol paste products against tapeworms in horses in field and critical trials. Eighty-seven horses naturally infected with tapeworms detected by fecal examination were divided into three groups. Thirty horses were given a single dosage of bithionol at 5 mg/kg directly into their mouths, and 51 horses at 10 mg/kg. Fecal examinations were carried out on day 14 after the treatment. Eighty-seven percent of the horses treated with 5 mg/kg of bithionol and 100% of the horses treated with 10 mg/kg were negative for tapeworm eggs in their feces. Two horses from each of the treated groups were necropsied on day 14 after the treatment. There were no tapeworms detected in their gastrointestines. Tapeworms in the feces excreted from the treated horses were morphologically identified as Anoplocephala perfoliata. Thirteen percent of horses in the 5 mg/kg group and 20% in the 10 mg/kg group excreted loose or diarrheal feces for 2 days after the treatment. No other clinical signs were observed in the horses in either group. Meanwhile, six horses in the control group were positive in fecal examination on the same day (day 14). In one of them were found 27 A. perfoliata when it was necropsied on that day. These results showed that bithionol paste products, when administered at the rate of 10 mg/kg of bithionol, satisfactorily deworm A. perfoliata in horses.