Hemangiosarcoma (HSA) in Dogs
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. In dogs, hemangiosarcoma is considered to be a very aggressive tumor and can spread rapidly to other organs. Hemangiosarcoma is commonly abbreviated as “HSA”.
Hemangiosarcoma is more common in dogs than in cats. It usually occurs in middle-aged to older dogs 9 to 11 years of age, and German shepherds appear to be predisposed to developing this cancer.
The most common primary location of this cancer in dogs is the spleen. Other primary locations include the heart, liver, skin, and bone; however, it can start in any location where blood vessels are present. These tumors usually spread to the lungs, liver, spleen and heart.
Hemangiosarcoma in Dogs: What to Watch For
Signs of hemangiosarcoma in dogs may include:
- Anemia, weakness and collapse
- Pale or white gums
- Difficulty breathing
- Exercise intolerance
- Fluid build-up of the abdomen
- Mass or lump under the skin
- Swelling in the bone
- Pain in the bones
Diagnosis of Hemangiosarcoma in Dogs
Diagnostic tests that may be needed to recognize hemangiosarcoma and to direct treatment include:
- Complete blood count (CBC) including platelet numbers
- Clotting tests
- Serum chemistry panel and urinalysis
- Abdominal radiographs (X-rays) and/or ultrasound
- Abdominal tap
- Chest X-rays
- Ultrasound of the heart
- Electrocardiogram (EKG)
- Pericardial tap
Treatment of Hemangiosarcoma in Dogs
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. Dogs with poorly-pigmented skin and sparse hair coats, such as the whippet, saluki, bloodhound and English pointer, are more likely to develop this form of hemangiosarcoma. 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 in dogs may include the following:
- Intravenous fluids
- Blood transfusion
- Pericardial tap
- Radiation therapy
Diagnosing Hemangiosarcoma in Dogs
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.
Biopsies for Diagnosing Canine Hemangiosarcoma
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.
Treating Hemangiosarcoma in Dogs
Stabilization is usually needed when the tumor causes internal bleeding or a build-up of fluid around the heart. The symptoms can be life threatening; pets that have bleeding into the abdomen can go into shock and require emergency care. Dogs that have a build-up of fluid around the heart can show signs of heart failure and collapse.
Intravenous fluids may be administered. This usually involves placement of a catheter and rapid administration of intravenous fluids.
Transfusions may be performed. If a dog is very anemic, a blood transfusion may be required to stabilize the patient. A transfusion can consist of either whole blood or just red blood cells.
When the tumor causes pericardial effusion, it may be necessary to remove the fluid around the heart to allow the heart to beat more effectively. A pericardial tap is the procedure by which fluid is removed from around the heart. Generally, once the fluid is removed, the patient improves, although he must be monitored for recurrence of the fluid. Periodic removal of the fluid may be needed.
Surgery for Canine Hemangiosarcoma
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 dog when the tumor is bleeding.
When the tumor occurs in the spleen, a splenectomy is performed. This involves removing the entire spleen. The spleen can be removed without having an adverse effect on health. At the time of surgery other organs, particularly the liver, should be examined and a biopsy taken of any abnormal tissue. By removing the spleen, the source of bleeding is removed and the patient stabilized. Potential complications following removal of the spleen include: infection, continued bleeding, failure of the incision to heal and an abnormal heart rhythm.
When the tumor occurs in the heart, it is almost always found on only one chamber of the heart, the right atrium. It may be possible to remove the tumor surgically. The outer covering of the heart, the pericardium, can also be removed to prevent future build-up of fluid around the heart. 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 skin or in the tissues immediately below the skin, surgery is required. It is important that normal tissue surrounding the tumor be removed, along with the mass, because cells from this tumor frequently infiltrate the surrounding tissues. Failure to remove these cells will result in the tumor regrowing.
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.
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. Dogs 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 dogs, 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 Canine Hemangiosarcoma
Radiation therapy may be performed in dogs and involve the following:
- Full course radiation therapy: This type of radiation therapy is used when a tumor involving the skin or underlying tissues cannot be completely removed. In order for full course radiation to be effective, all visible evidence of the tumor must be removed first with surgery. In this situation, 16 to 19 treatments of radiation may be given over a four to six week period of time. The side effects include hair loss and redness and ulceration of the skin. These side effects are present only for a three to four week period of time and can be managed with medications.
- Palliative radiation therapy: This type of radiation therapy can be used to control symptoms such as pain when the tumor cannot be entirely removed with surgery. It involves giving a few large doses of radiation therapy to the tumor over a two to three week period of time. Side effects are very few and is most commonly used when the tumor occurs in the bone.
Prognosis for Dogs with Hemangiosarcoma
Prognosis may vary. The recommended course of treatment and outcome depends upon the location of the tumor.
Hemangiosarcoma of the spleen is aggressive. The recommended treatment is surgery (to remove the spleen) and chemotherapy. If the only treatment is removal of the spleen, the survival time is short (between one to two months). If chemotherapy is given after surgery the survival time is improved and is about six months.
When the hemangiosarcoma is in the liver, the treatment recommendations and outcome are similar to that of the spleen. When the hemangiosarcoma is in the heart, the recommended treatment is to remove the tumor if possible and follow-up with chemotherapy. With surgery alone, the survival time is less than four months. With chemotherapy, the survival time is extended to six months or more.
If the tumor occurs in only the upper layer of the skin the outcome is excellent. In that situation, the only required treatment is complete removal of the tumor with surgery. When the tumor involves the deeper layers of the skin or the underlying tissues, there is a greater potential for spread of the tumor to other organs. The recommended treatment is to remove the entire tumor with surgery and to follow-up with chemotherapy. If the entire tumor cannot be removed with surgery but is reduced to the level where the tumor cannot be felt, radiation therapy is recommended in addition to the surgery and chemotherapy. In this situation, survival times are between eight to 12 months with treatment.
Hemangiosarcoma of the bone is an aggressive tumor. The most common bones affected are the ribs, forelimbs and vertebrae. The recommended treatment is removal of the affected bone if possible followed by chemotherapy. In situations where the affected bone cannot be removed, palliative radiation therapy can be given to control pain. The survival time for hemangiosarcoma of the bone with treatment is around six months.
Follow-Up Care for Dogs with Hemangiosarcoma
Seek veterinary attention promptly if your dog develops pale gums or signs of weakness or collapse. These may be symptoms of hemangiosarcoma or other potentially serious conditions.
Have any new lumps on your dog evaluated by your veterinarian. Hemangiosarcoma of the skin or underlying tissues can be difficult to distinguish from less serious skin tumors. Early detection may increase the possibility of successful treatment.
Restrict your dog’s activity after surgery until suture removal. Monitor the incision for any signs of redness, swelling or discharge. Keep your pet from chewing or scratching at the incision.
If your dog receives chemotherapy monitor him for changes in appetite and activity. The most common side effects of chemotherapy are appetite loss, vomiting and/or diarrhea. Mild signs can frequently be managed at home with diet changes. Anti-nausea or anti-diarrhea medications can also be prescribed. Your veterinarian should be notified if the signs are severe or last longer than a few days. Rarely, your veterinarian may recommend hospitalization to prevent dehydration.
Signs of infection include loss of appetite, fever and extreme tiredness. Infections in patients with low white blood counts are serious and require intravenous antibiotics.
Minimize your dog’s exposure to the sun, especially for dogs that are poorly pigmented and have a sparse haircoat. Hemangiosarcoma of the skin can be caused by excessive exposure to the sun.