Heart Cancer (Hemangiosarcoma) in Dogs

Hemangiosarcoma is an aggressive, malignant and metastasizing tumor that originates from blood vessels (tubular structures carrying blood to different organs eg capillaries, veins, arteries etc). Hemangiosarcoma can affect any body part with blood vessels including skin, spleen, lungs, kidneys, brain and liver etc however, this sarcoma (a tumor of connective tissues) most commonly affects the heart. The most common heart tumor in dogs, hemangiosarcoma is an incurable tumor of cells that line blood vessels, called vascular endothelial cells. Because the tumor affects blood vessels, it is often associated with internal bleeding which can be life threatening for the pet. The sarcoma spreads rapidly due to its highly invasive nature. An almost exclusively dog tumor, hemangiosarcoma is reported mostly in mid to large size breeds including Boxers, German Shepherds and Golden Retrievers. Dogs older than six years are more commonly affected.

This tumor is not easy to diagnose and it goes undetected until complications arise. As it affects blood vessels, hemangiosarcoma is frequently filled with blood. The blood vessles burst upon reaching an unstable size, causing life-threatening internal bleeding. The tumor may also interfer with ability of heart to work effectively. The sarcoma can affect heart rhythm, cause accumulation of blood in pericardial sac secondary to burst blood vessels or cause abdominal swelling which in turn puts pressure on heart and other organs. Other complications that may arise include regenerative anemia.

Most of the symptoms associated with hemangiosarcoma are related to heart problems rather than the tumor itself, making the diagnosis not easy. These symptoms include

Difficult breathing

Accumulation of fluid within abdominal cavity – visible abdominal distention

Accumulation of fluid within thoracic (chest) cavity

Sudden loss of consciousness/fainting (syncope)

Inability to perform routine exercises

Trouble with coordination (ataxia)

Irregular heart beats/arrhythmia

Enlargement of the liver



Loss of appetite (anorexia)

Weight loss

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