VASCULAR NEOPLASMS OF DOGS

This paper reviews the clinicopathological features of canine neoplasm s which arise from the malignant transformation of endothelial cells. The majority of canine vascular neoplasms are malignant, and hemangios arcoma is the most prevalent histopathological type. Hemangiosarcoma a rises most commonly in the spleen, heart, and skin of dogs. Because th e biological behavior of this tumor appears to be site-dependent, it i s logical to subclassify canine hemangiosarcoma as distinct disease en tities according to primary tumor location. Splenic hemangiosarcoma ha s a high propensity for early metastasis. German shepherds and Labrado r retrievers greater than eight years of age have an increased risk fo r splenic hemangiosarcoma. Treatment consists of splenectomy and adjuv ant therapy directed at controlling residual disease. Cardiac hemangio sarcoma is also associated with aggressive biological behavior, althou gh there is limited information available regarding patient outcome af ter attempted curative therapy. Cutaneous hemangiosarcoma has a low pr opensity to metastasize, in contrast to splenic and cardiac hemangiosa rcoma. Hemangiosarcomas that arise in other sites (subcutis, bone, liv er) as well as hemangiosarcoma of the central nervous system are also discussed. By considering canine hemangiosarcoma as a collection of di seases, future investigations may lead to a better understanding of et iopathogenesis and the mechanisms responsible for apparent site-specif ic differences in biological behavior. Ultimately, this approach will also lead to more accurate tumor staging, more effective therapy, and improved prognosis.