Hemangiosarcoma is cancer of the vascular endothelium, or the blood vessel walls. It accounts for 0.2 to 3 percent of all canine tumors with a mean age at diagnosis of 9 to12 years.(1) Hemangiosarcoma most commonly affects the spleen and heart of golden retrievers, Labrador retrievers and German shepherds. It is estimated 25 percent of dogs that present with splenic hemangiosarcoma also have a tumor of the heart.(2) Non-visceral forms do occur, usually affecting the skin. Because metastasis and local invasion occur early in the course of this disease, many cases are not diagnosed until the ruptured tumor tissue causes catastrophic hemorrhage.
Dogs with hemangiosarcoma may show non-specific signs such as lethargy and anorexia, which may be episodic if small hemorrhages of the tumor occur repeatedly. Unfortunately, a common presentation is collapse, increased heart and respiratory rates, and pale mucous membranes caused by substantial hemorrhage of a ruptured tumor. Learn to assess your dog’s mucous membranes by lifting the upper lip to examine the color of the gums and lip (Fig. 1). Even dogs with pigment on their gums will have some areas of pink to evaluate. Practice this exam regularly to learn what is normal for your dog in various lighting conditions, as prompt diagnosis and treatment of this disease is critical for your dog’s survival.
At the clinic, a veterinarian may palpate an enlarged spleen, or may find palpation is difficult due to the presence of a blood-filled abdomen. Bloodwork may reveal anemia, thrombocytopenia (low platelet count), or disseminated intravascular coagulation (a deadly coagulation disorder in which small blood clots occur throughout the system, blocking blood vessels and depleting coagulation compounds). Radiographs and/or ultrasound may show an enlarged spleen with multiple nodules or cavitations, free fluid in the abdomen, or masses in the heart or abdominal organs.
Abdominocentesis (tapping the abdominal cavity with a needle) may produce frank blood. Examination of cytology from a fine needle aspirate of the affected organ may be useful in diagnosing hemangiosarcoma, but the procedure carries risk, as it may trigger bleeding.
Because hemangiosarcoma often is associated with substantial hemorrhage and a very poor prognosis, the difficult decision must often be made at the time of diagnosis to a) pursue emergency surgery to remove the bleeding tumor, or b) euthanize the dog. Median survival time following surgery alone for splenic hemangiosarcoma is two to three months, and for cardiac hemangiosarcoma, three to five months.(3) Traditional chemotherapy may improve survival to 140 to 202 days, but no single protocol has shown superiority.(1)
Emerging therapies for hemangiosarcoma include immunotherapy, antimetastatic agents, and mushroom extracts which show promise for prolonging survival. In a future article, we will discuss these exciting advancements.
- Clifford CA, Mackin AJ, and Henry CJ, (2000). Treatment of Canine Hemangiosarcoma, 2000 and Beyond. J Vet Intern Med, 14:479–485.
- Waters et al, (1988). Metastatic Pattern in Dogs with Splenic Hemangiosarcoma: Clinical Implications. J Small Animal Pract, 29:805.