Macroscopic lesions have not been reported in pregnant dams; however, microscopic lesions have been seen in tissues of gilts killed after their fetuses were infected by transuterine inoculation of virus. Gilts that were seronegative when their fetuses were infected at 70 days of gestation had focal accumulations of mononuclear cells adjacent to the endometrium and in deeper layers of the lamina propria when they were killed 12 and 21 days later. In addition, there were perivascular cuffs of plasma cells and lymphocytes in the brain, spinal cord, and choroid of the eye. When fetuses were infected earlier in gestation (35, 50, and 60 days) and their dams were killed 7 and 11 days later, the lesions were similar. However, uterine lesions were more severe and also included extensive cuffing of myometrial and endometrial vessels with mononuclear cells. Only focal accumulations of lymphocytes were seen in uteruses of gilts that were seropositive when their fetuses were infected.