Section: Veterinary Care In-depth
Diagnosis
A complete blood count (CBC), including evaluating platelet numbers, will allow your veterinarian to check whether anemia (a low red blood cell count) is present or not. In addition to causing anemia, hemangiosarcoma can also cause a low platelet count. Platelets are needed in order for clotting to occur, so when the platelet count is low, there is an increased risk of bleeding.
Dogs with hemangiosarcoma can also have changes in other clotting tests. The risk of bleeding may be increased when the clotting tests are abnormal. This information is important for your veterinarian when surgery is being considered.
Serum chemistry panel and urinalysis tests are run to identify any underlying diseases such as kidney or liver disease.
Abdominal radiographs (X-rays) or ultrasound are sometimes performed to identify if there is a mass present in the abdomen. However, when there has been bleeding into the abdomen, X-rays become difficult to evaluate. An ultrasound of the abdomen will allow the liver and spleen to be evaluated in greater detail than X-rays. It should be kept in mind that older dogs frequently have nodules in the liver and spleen that are considered aging changes and this does not mean that cancer is present.
An abdominal tap may be performed to confirm the presence of free blood in the abdomen. Unlike blood in blood vessels, free blood in the abdomen does not clot. The blood can also be examined under a microscope for the presence of cancerous cells in the fluid. However, the absence of cancerous cells does not preclude the diagnosis of hemangiosarcoma.
When there is free fluid around the heart, it is often possible to remove a portion of this fluid using a needle and syringe. This is called a pericardial tap. A pericardial tap is often done with the assistance of an ultrasound so that there is less risk of puncturing the heart.
Chest X-rays may be routinely taken in any dog suspected of having cancer. The lungs are one of the most common sites of spread of hemangiosarcoma. In addition, the size and shape of the heart can be evaluated to see if there are signs of either a mass in the heart or pericardial effusion.
An ultrasound of the heart may be performed to allow identification of either a mass in the heart or fluid around the heart. However, ultrasound may not be able to identify small masses in the heart. An ultrasound of the heart also allows evaluation of heart function, which is important if chemotherapy is planned.
An EKG allows for identification of any irregular heart rhythms (arrhythmias) that may be secondary to hemangiosarcoma in the heart. Arrhythmias are common in dogs that have tumors in the spleen or that have just undergone removal of the spleen.
Biopsy
A biopsy may be necessary to make a definite diagnosis. If only a small sample is taken or if the tumor is very abnormal, it may not be possible to confirm that it is hemangiosarcoma. In the case where only a small sample is submitted, additional biopsies may be needed. In the case where the tumor is abnormal, special stains can be used to confirm that it is hemangiosarcoma. The type of biopsy depends upon the location of the tumor.
When the tumor occurs in the spleen, the entire spleen is usually removed and submitted for biopsy. In addition, all other organs in the abdomen are usually examined and biopsies taken of any tissue that looks abnormal. The liver is usually examined carefully since it is common for hemangiosarcoma to spread to this site.
It is more difficult to obtain a diagnosis when the tumor occurs in the heart than in the spleen. Generally the only way to get a biopsy in this location is to enter the chest cavity surgically.
When the tumor occurs in the skin or in the tissues directly below the skin, several types of biopsies can be obtained. A small piece of the tumor can be obtained to confirm the diagnosis prior to any further treatment. It is also possible in some cases to remove the entire tumor for biopsy.
When the tumor occurs in a bone, generally only a small sample of the bone is taken to obtain a diagnosis.
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