Hemangiosarcoma
（重定向自Haemangiosarcoma）
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. A frequent cause of death is the rupturing of this tumor, causing the patient to rapidly bleed to death.