Experimentally induced sarcocystis infection in calves: pathology.

Calves fed sporocysts of Sarcocystis isolated from the feces of dogs and coyotes became anorectic, lost weight, and became anemic and prostrate, and died. The most severe pathologic changes occurred between 26 and 33 days after infection; schizonts were found throughout the body. Schizonts were not found after this time. Sarcocytis cysts were in skeletal and cardiac muscles between 33 and 54 days. Necropsy revealed lymphadenopathy, paleness of the mucous membranes and visceral organs, ascites, hydrothorax, hydropericardium, and serous atrophy of fat. Ecchymotic or petechial hemorrhage was in heart, brain, serosa of the alimentary tract, and urinary bladder. Microscopic changes observed in nearly all calves consisted of hemorrhage, mononuclear cell (primarily lymphocytic) infiltration and edema in heart, brain, liver, lung, kidney, and striated muscle. Necrotizing myocarditis with dystrophic calcification of the striated muscle and fat, as well as nonsuppurative inflammation of meninges and glial nodules in the brain, was observed in several calves.