Hemangiosarcoma (Splenic or Visceral) in Dogs

Visceral hemangiosarcoma is a life-threatening form of cancer and carries a poor prognosis. It usually goes undetected until an abdominal mass is found during physical examination. Some cases have multiple small bleeds before diagnosis and have a history of weakness episodes that resolve and recur.

HSA tumors originate in the bone marrow and develop wherever the cancer cells collect in the bloodstream. The cells multiply, forming tumors that may occur anywhere in the body. Common locations include the spleen, heart, liver, and intestines.

Cardiac HSA often has no symptoms until heart function fails, resulting in acute collapse. Sometimes there are no obvious symptoms until a severe bleeding event occurs, leading to sudden death.

The same form of cancer also occurs in the skin. Cutaneous hemangiosarcoma is more common than visceral and carries a better prognosis.

Visceral HSA is a serious condition which is usually fatal. It is most commonly seen in middle-aged or older dogs. Splenic HSA is more common in golden retrievers and cardiac HSA is more common in German shepherd dogs.

HSA often presents as an emergency with acute bleeding and collapse. Dogs with a bleeding tumor require emergency veterinary treatment.

HSA originates in the bone marrow cells that go on to form new blood vessels. The underlying trigger has not been identified. Breed predisposition suggests genetic factors may contribute to development of HSA.

Symptoms of HSA vary depending with the location and severity of the tumor.

HSAs have a substantial blood supply and are also fragile, so they most commonly present with symptoms of blood loss.

Further investigation of HSA includes:

• Physical examination
• Blood work
• Biopsy
• Diagnostic imaging

Treatment options include:

• Surgical removal of the tumor: This is the treatment of choice for splenic HSA and in some cases of liver HSA, but not possible in cardiac HSA
• Pericardiectomy: surgical creation of a hole in the sac surrounding the heart to remove blood clots and reduce pressure on the heart muscle
• Chemotherapy

Symptomatic treatment options include:

• Fluid therapy
• Blood transfusion
• Pain relief

Due to poor prognosis, palliative care or euthanasia may be the most humane options to mitigate significant decline in quality of life.

All forms of visceral HSA carry a poor prognosis as they are aggressive tumors that readily metastasize to other organs such as the liver and lungs. Survival times up to 6 months are possible with extensive medical and surgical treatment, but many cases are euthanized due poor prognosis.

HSA is not a preventable condition as the underlying triggers are not known. HSA may be an inherited trait in some dogs, so blood lines that have an increased rate of HSA should not be bred.

Visceral HSA is moderately common in dogs accounting for 5-7% of all malignant tumors.

• Surgical removal of the tumor
• Pericardiectomy
• Medication
• Chemotherapy
• Symptomatic treatment
• Palliative care