Pulmonary emboli of bone marrow associated with femoral fracture in a calf

Abstract

An eight-month-old Holstein bullock with a history of recumbency and swelling of the proximal right extremity was necropsied. Gross lesions included a complete fracture in the proximal third of the right femur and multifocal haemorrhages of the surrounding soft tissues. Histologically, there was massive bone marrow emboli of varying sizes located in the pulmonary arterial branches. The emboli were osmium tetroxide, factor VIII-related antigen and myeloid-histiocyte antigen positives, consistent with fat and haematopoietic cells of bone marrow origin. No gross or microscopic abnormalities were detected elsewhere.