Hemangiosarcoma is a rapidly progressing, highly metastasizing and malignant form of cancer that arise in the cells that line the blood vessels, called vascular endothelium. The tumor arise from the endothelial cells (the cells that line the interior surface of blood vessels). It can affect any organ of the body but spleen and liver are among the most commonly affected organs. These tumors invade locally and also metastasize (spread to other organs). Splenic tumors have often spread to the liver and lungs by the time of diagnosis.
The tumor starts as a large mass in liver or spleen and rapidly progresses through blood stream to invade liver, lungs and in some cases, heart and brain.
The tumor is filled with blood and any disturbance causes profused bleeding that may result in tumor rupture, severe hemorrhage, collapse and sudden death.
German Shepherds, Boxers, Great Danes, English Setters, Golden Retrievers and Pointers are breeds which are predisposed to this condition. Male dogs are at greater risk. The mean age of occurance is 8 to 10 years but the tumor is seen in dogs less than one year old.
Symptoms depend on the organ affected. Common symptoms of spleen and liver hemangiosarcoma include
Muscle incoordination (ataxia)
Partial loss of movement (paresis)
Pale mucous membranes
Rapid heartbeat (tachycardia)
Abdominal (peritoneal) fluid
Palpable abdominal mass
Acute blood loss (often fatal)