Sudden death caused by pulmonary tumor embolism in a dog

Tumor embolization is a well-described cause of unexpected death in human oncologic patients; however, it is poorly explored in veterinary medicine. We report a case of pulmonary tumor embolization in a dog with sudden death. During necropsy, a neoplastic mass was observed replacing the left adrenal gland and forming an intravascular thrombus within the central adrenal vein. A large embolus occluded the left pulmonary artery. The adrenal mass was histologically confirmed as a pheochromocytoma, and the embolus was constituted of neoplastic cells. Multiple smaller neoplastic emboli were observed within the pulmonary artery branches. Tumor embolization should be considered as a possible cause of sudden death in dogs, particularly in oncologic patients.