Ovine abortion and stillbirth due to purulent placentitis caused by Yersinia pseudotuberculosis

Yersinia pseudotuberculosis was isolated from an aborted placenta and stillborn lamb from a sheep flock having multiple abortions. Given intravenously, it caused elevated body temperatures and purulent placentitis in eight of nine ewes. Two ewes died following infection at 2.5 months of gestation. Two ewes infected at 3.5 months gestation aborted; three infected at four months gave birth to weak, premature, or moribund lambs. One ewe infected at 4.5 months gave birth to a healthy lamb. One lamb which died minutes after birth had focal necrotizing hepatitis, a lesion observed in a stillborn lamb during the original disease outbreak. Y. pseudotuberculosis was reisolated from endometrial, placental, and fetal lesions of experimentally infected animals.