RESUMO
To identify pathologic alterations, sixteen cows, in the last 3 months of gestation, all cross-breed, Holstein x Zebu, serum positive for Sarcocystis, were selected and divided into four groups of four animals each. The first group was considered as control and the other three groups were experimentally infected with 1x10(4) (2nd group), 5x10(4) (3rd group) and 1x10(5) (4th group) sporocysts obtained from dog's feces. The gross lesions in the cows were consisted of pale mucous membranes, paleness of the skeletal striated muscle and enlargement of lymph nodes, heart, liver, spleen and lungs. In the aborted fetus, the most prominent gross lesion were excess of fluid in peritoneal and thoracic cavities, and petecheas in the surface of intercostal muscles, thymus and spleen. On histological sections, no parasitic form was found in the tissues of the fetus, placenta or uterine tissue of the exposed cows. However, meronts, young and mature cysts of S. cruzi were observed in striated muscle. In the aborted fetus, hemorrhage, was the main histological lesion observed in brain, cerebellum and kidneys.