Canine and Feline Hemangioma and Hemangiosarcoma

1 Symptoms

Hemangiomas and hemangiosarcomas are tumors that arise from the lining of blood vessels. A hemangioma is a slow-growing, benign growth that rarely becomes malignant or spreads. Hemangiosarcoma is a destructive malignant tumor that behaves aggressively once it develops.

These tumors can occur anywhere in the body, including the skin, subcutaneous tissue, and deeper sites such as the tongue, nasal cavity, liver, spleen, and bone. In the skin and soft tissue they most often appear on the limbs, spleen, chest, and perineal area. They are made up of dilated, blood-filled spaces with no true capsule and an infiltrative growth pattern; the cut surface looks dark red and weeps blood.

Bone hemangiosarcoma typically affects pets between about 3 and 16 years of age, most often in the upper and lower ends of the long limb bones, pelvis, sternum, or upper jaw. It causes pain, lameness, loss of function, and bone destruction. X-rays show severe patchy bone lysis with a moth-eaten appearance, and pathologic fractures are common. The tumor progresses rapidly and often spreads to distant sites, so the prognosis is poor.

Hemangiosarcoma of the spleen or heart can cause sudden collapse and internal bleeding. Affected pets may show weakness, pale gums, a swollen abdomen from internal blood loss, and lethargy.

2 Causes and Transmission

The exact cause is not fully understood; genetic background and possibly environmental factors are suspected. Hemangiosarcoma is uncommon but striking, and certain large breeds such as the Great Dane, Boxer, and German Shepherd are overrepresented. There is no contagious transmission between pets.

3 Diagnosis

Diagnosis is based on imaging such as X-ray and ultrasound, supported by biopsy and microscopic examination of the tissue. Because hemangiosarcoma often spreads, especially to the lungs, liver, and spleen, before any signs appear, chest imaging is important for staging. Blood work may reveal anemia and evidence of internal bleeding.

4 Treatment

Early, localized tumors may be managed with surgical removal where feasible. Because many hemangiosarcomas have already spread by the time of diagnosis, surgery often cannot cure or meaningfully extend life and may only add discomfort, so its value must be weighed carefully with your veterinarian.

Veterinary-directed chemotherapy using combinations of agents such as vinca alkaloids and alkylating drugs may be used to slow progression in selected cases. Spleen- or heart-based tumors often require emergency stabilization for internal bleeding, including fluid support.

Supportive care, including appropriate nutrition and electrolyte support, helps maintain strength during recovery.

5 Prevention and Home Care

There are no reliable preventive measures. Routine veterinary check-ups and prompt investigation of new lumps, unexplained lameness, weakness, pale gums, or abdominal swelling are the most useful safeguards.

Because hemangiosarcoma is aggressive and surgery often cannot cure it once spread, early detection and realistic expectations about prognosis matter. Follow your veterinarian’s guidance on monitoring and palliative care to keep your pet comfortable.