Hemangiosarcoma (HSA) also called malignant hemangioendothelioma or angiosarcoma is a deadly cancer that originates in the endothelium and invades the blood vessels. Hemangiosarcoma is more common in dogs than any other species. It accounts for 5% of all non-cutaneous primary malignant neoplasms and 12% to 21% of all mesenchymal tumors in dogs.
- Dermal– Found on the skin
- Hypodermal- Found under the skin
- Visceral- Found on the spleen, pericardium and the heart
Other frequent sites include the right atrium, skin and sub-cutis and liver. Cases have also been reported in the lungs, kidneys, oral cavity, muscle, bone, urinary bladder, left ventricle, uterus and retroperitoneum. The skin tumors consist of 2.3% to 3.6%. While splenic malignancies account for 45% to 51% and are therefore the most commonly diagnosed and the deadliest. Hemangiosarcoma is mostly seen in middle-aged to older dogs. Though it can occur in any breed, German shepherds, Golden Retrievers, Labradors have a predilection for the disease. It is also believed that male dogs are slightly predisposed than their female counterparts.
The etiology of this disease is not exactly known. However, its exclusive occurrence in dogs points to the heritable factors that contribute to the risk. Ultimately, the interactions of these risk factors with the environment probably lead to the mutations that give rise to the tumor. Lesions arise when the cell gather mutations that render the normal constraints of growth and genetic integrity of cells null and void. Mutations take place because the enzymes that control cell division are not fool proof. Some cells in the body divide constantly to replace dead or damaged cells. Therefore, mutations are introduced into the body regularly. Cutaneous hemangiosarcoma (found on the skin) are said to be the result of exposure to sunlight.