what is a hemangiosarcoma
Hemangiosarcoma is a rapidly growing, highly invasive variety of cancer, occurring almost exclusively in dogs and rarely in cats. It is a sarcoma arising from the lining of blood vessels; that is, blood-filled channels and spaces are commonly observed microscopically.t also occurs in cats, but is much rarer. Dogs with hemangiosarcoma rarely show clinical signs until the tumor has become very large and has metastasized. Typically, clinical signs are due to hypovolemia after the tumor ruptures, causing extensive bleeding.