Efficacy of ponazuril in weaned feeder lambs with naturally acquired coccidiosis

Abstract

Coccidiosis is a common and economically significant parasitic disease that causes diarrhea, weight loss, and death in lambs. Coccidiostats currently labeled in the US for ovine coccidiosis are challenging to administer at effective doses in sick lambs and clinically ineffectual when used late in the disease process. Newer triazinone-class coccidiocidial drugs, such as toltrazuril (Baycox®, Bayer Animal Health) are effective across a greater range of Eimeria's life cycle, resulting in improved clinical response and treatment compliance. Ponazuril (toltrazuril sulfone), an active metabolite of toltrazuril, is labeled in the United States for treatment of equine protozoal myeloencephalitis and is being used extra-label in sheep and goats for treatment of coccidiosis despite a lack of published data regarding its clinical effectiveness in sheep. The objective of this study is to determine the efficacy (fecal oocyst shedding, fecal consistency, and lamb growth performance) of a single low (2.27 mg/lb; 5 mg/kg) or high (9.1 mg/lb; 20 mg/kg) oral dose of ponazuril for treatment of naturally-acquired coccidiosis (Eimeria spp) in commercial feeder lambs.