Overview of Feline Hemangiosarcoma
Hemangiosarcoma is a malignant cancer of the cells that form blood vessels. Because these tumors start in blood vessels, they are frequently filled with blood. Consequently, when a blood-filled tumor ruptures, it can cause problems with internal or external bleeding. Hemangiosarcoma is considered to be a very aggressive tumor and can spread rapidly to other organs.
In cats, it occurs in older animals and there is no breed predisposition. Since this is a cancer of the blood vessels, it can start anywhere. In cats, this cancer occurs about half the time in internal organs (usually the spleen and liver) and half the time in the skin. These tumors usually spread to the lungs, liver, spleen and heart.
Signs of this disease are usually the result of the tumor rupturing, which causes bleeding. This may occur without any warning, and the symptoms will depend upon where the tumor is located.
What to Watch For
Diagnosis of Hemangiosarcoma in Cats
Diagnostic tests that may be needed to recognize hemangiosarcoma and to direct treatment include:
Treatment of Hemangiosarcoma in Cats
The treatment and prognosis depends upon the location of the tumor. When the tumor occurs in an internal organ such as the spleen or heart, the chances of long-term survival are poor. Treatment is more successful when this cancer occurs in the skin.
Exposure to the sun may play a role in the development of this type of skin cancer. There is no known cause of hemangiosarcoma in other locations. In humans, exposure to certain chemicals (such as vinyl chloride) has been implicated as a cause.
Treatment for hemangiosarcoma may include the following:
Home Care and Prevention
Seek veterinary attention promptly if your pet develops pale gums, signs of weakness or collapse. Have any new lumps on your pet evaluated by your veterinarian.
Minimize your pet's exposure to the sun, especially cats that are poorly pigmented and have a sparse hair coat.
In-depth Information on Hemangiosarcoma in Cats
Hemangiosarcoma must be differentiated from other diseases that might cause similar clinical signs. For example, diseases of the heart such as an irregular heart rhythm can cause pets to show signs of weakness or collapse. There are several other malignant tumors that can appear as a mass in the spleen including:
These tumors can also rupture leading to bleeding from the spleen and the development of anemia. Some systemic cancers may involve the spleen either in addition to other sites or as the primary site. The two most common cancers where this occurs are lymphosarcoma and mast cell tumor. Although not common, other tumors can spread or metastasize to the spleen causing similar signs as hemangiosarcoma.
Other diseases that can cause similar signs include:
Biopsy for Hemangiosarcoma in Cats
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.
Surgery for Hemangiosarcoma in Cats
Surgery may be performed, and the type will depend upon the location of the tumor. In some cases emergency surgery is required to stabilize a patient when the tumor is bleeding.
Potential complications of this surgery include bleeding, infection, failure of the surgery site to heal, introduction of air into the chest cavity causing difficulty breathing and an abnormal heart rhythm.
When the tumor occurs in the bone, it may be possible to remove the tumor by removing the bone itself. This is possible only in certain locations such as a leg or a rib. In some cases, it is only possible to get a biopsy of the tumor.
Chemotherapy for Feline Hemangiosarcoma
Due to the early spread of this tumor, chemotherapy is frequently recommended in addition to other treatments. The only exception to this is when the tumor is localized to the very uppermost layer of the skin. Then surgical removal of the tumor may be all that is required.
The most commonly used chemotherapy drug is doxorubicin. This drug is administered intravenously once every three weeks. Cats handle this drug well and the risk of serious side effects is low, between 5 to 10 percent. Potential side effects include gastrointestinal problems, including nausea, vomiting, diarrhea or loss of appetite, and a drop in the white blood cell count, leaving a pet susceptible to infection. If multiple treatments of this drug are given, cumulative side effects include heart problems. In order to prevent the cumulative side effects, the number of treatments is limited to six or less. In cats, a heart evaluation (ultrasound and EKG) is recommended prior to giving the drug and before the fifth and sixth treatment.
Other drugs that are used in the treatment of hemangiosarcoma are cyclophosphamide and ifosphamide. Cyclophosphamide is frequently given either with doxorubicin or immediately after. When ifosphamide is used, it is alternated with doxorubicin. Both of these drugs can cause gastrointestinal side effects and a drop in the white blood cell count. In addition, they can cause an irritation in the lining of the bladder causing blood in the urine and straining to urinate. If the drug irritates the bladder the signs will usually resolve in a few days to a few weeks.
Radiation Therapy for Hemangiosarcoma in Cats
Follow-up Care for Cats with Hemangiosarcoma
Radiation therapy may be performed and involve the following: