Hemangiosarcoma: Page 2 of 3

Clinical Signs

Symptoms vary depending on what organ is affected. Because the blood vessels in hemangiosarcoma tumors do not have normal connections, they are more likely to tear and bleed. This is why the first sign of this type of cancer can develop when a mass in the liver or spleen is bleeding.

A bleeding episode can cause weakness, lethargy, pale gums, decreased appetite and a painful abdomen. When these signs occur, it is important that a pet be examined by a veterinarian immediately. If a tumor is bleeding very quickly, surgery may be necessary to try to remove the mass and stop the bleeding.

If the tumor is bleeding slowly, clinical signs may wax and wane, meaning your pet will feel poorly one day but energetic a few days later. Some dogs have no observable symptoms from hemangiosarcoma. A mass may be incidentally discovered on a routine screening x-ray or during an ultrasound when investigating another health problem.


Imaging (x-ray, ultrasound etc.) can reveal a mass in the body but hemangiosarcoma as a diagnosis can only be reached when a pathologist evaluates a tumor, usually after the whole mass has been removed. Some masses in the liver or spleen can look like hemangiosarcoma with ultrasound but may actually be a different type of tumor or even just a hematoma (blood clot).

The pathologist report will define the type of mass.  When a hematoma or benign tumor, such as a hemangioma, is diagnosed, surgery to remove the mass can be curative. Because of this, it is important to keep in mind that prognosis cannot be determined based solely on the appearance of a mass.

Evaluation of the Body Systems

Ultrasound examination of the abdomen or the heart is the most common way that a potential hemangiosarcoma is identified. Before surgery to remove a mass in the liver or spleen, blood work to evaluate body organ function, as well as clinical staging involving x-rays of the chest, is recommended to determine if there is evidence of metastasis (spread of the cancer). Staging is a process of diagnostic testing to check other parts of the body for signs of illness or disease before proceeding with treatment and surgery.