Bovine saccocystosis: patholgic features of naturally occurring infection with Sarcocystis cruzi.

Naturally occurring bovine sarcocystosis caused death and illness in eight dairy heifers. Clinical disease was characterized by cachexia, peripheral lymph node enlargement, and anemia. Increased amounts of serum enzymes and anti-Sarcocystis antibody titers were present in affected animal. Macroscopic findings in two heifers at necropsy included emaciation and serous atrophy. Necropsied heifers (No. 1 and 2) contained different developmental stages of Sarcocystis cruzi; each stage was characterized by specific histopathologic findings. Heifer 1 had vascular endothelial schizonts in various soft tissues, with mild mononuclear cell infiltration, alveolar capillary fibrinous thrombi, and multifocal splenic necrosis. Heifer 2 had developing young S cruzi cysts, in myofibrils of cardiac and skeletal muscles, with a concurrent multifocal degenerative myositis. Marked lymphoid hyperplasia occurred in both heifers.