Porcine neonatal coccidiosis: evaluation of monensin as preventive therapy.

In this study, we evaluated the efficacy of monensin as a preventive therapy for porcine neonatal coccidiosis. Fifteen three-day-old piglets were given 50,000 sporulated oocysts of Isospora suis and eight of them received 15 mg/kg of monensin orally every other day. Seven piglets served as normal controls. Fecal samples were collected and checked for oocyst shedding. At 18 days of age, piglets were euthanized and necropsied.The onset of clinical signs was delayed in the treated group, but all inoculated piglets displayed anorexia, soft stool, or diarrheic feces. Treated piglets shed large numbers of oocysts in their feces (up to 201,200 oocysts per gram of feces). All infected piglets had lesions of villous atrophy in the jejunum and most of them were in the late atrophic or villous regrowth stages.The results of this study suggest that monensin does not prevent clinical signs, oocyst shedding, and intestinal lesions caused by I. suis in neonatal piglets.