Hemangiosarcoma of the Bone in Cats
Dr. Jeffrey Philibert
Complete physical exam. A thorough exam is necessary to not only localize the site of the cancer but also to assess your pet's general health. Your cat's general health may drastically influence the treatment options that your veterinarian recommends.
Medical tests are needed to establish the diagnosis, exclude other diseases and determine the impact of hemangiosarcoma on your cat. Tests that your veterinarian may wish to perform include:
Radiographs (X-rays) of the affected body part. Although the appearance of a the bone on an X-ray may be suggestive of cancer, X-rays are not diagnostic of this condition.
Radiographs of the chest. Because the heart is a common location for this type of cancer, X-rays of the chest should always be taken prior to any type of surgery being performed. These radiographs will allow your veterinarian to assess the size of the heart and may give some indication as to whether masses are present, although echocardiograms are much better for seeing heart masses. Cats that already have evidence of heart or lung cancer are not good candidates for therapy because their disease is advanced.
Abdominal radiographs. X-rays are often taken of the abdomen to assess the outline of organs such as the liver, spleen, kidneys and lymph nodes. These are common sites for hemangiosarcoma.
Abdominal ultrasound (sonogram). This specialized procedure may require referral to radiology specialist. Ultrasound machines are computerized and have a probe that the doctor places on the surface of the skin. The probe transmits sounds waves, which bounce off the inside of the body and back to the probe. The computer then assembles these sound waves into a picture that shows internal body structures. It is a useful tool for helping to determine whether the cancer has spread to any of the soft-tissue body organs such as the liver, kidneys, spleen, intestines and lymph nodes. There is no risk to your pet with this procedure. It usually requires the hair on your pet's belly to be shaved in order to get the best view through the skin.
Cardiac ultrasound. This is a similar exam as outlined in abdominal ultrasound. This test allows the veterinarian to examine the heart for the presence of any masses or other abnormality.
Complete blood cell count (CBC). This blood test counts the number of red blood cells (cells that carry oxygen in the body) and white blood cells (cells that fight infection). This is a standard test to screen your pet's general heath and to ensure that it is safe to perform other procedures, such as surgery. However, it does not indicate if there is cancer in the blood.
Biochemical blood profile. This blood test assesses the general health of your pet's organs by assessing the health of the liver and kidney function and measuring levels of electrolytes such as potassium and sodium. Dysfunction may or may not be associated with the spread of cancer to an organ.
Urinalysis. Like blood tests, a urine test provides your veterinarian information about your cat's general health. Most importantly it assesses the health of the kidneys, but it also indicates the presence or absence of a urinary tract infection. The urine may be collected by catching some in a cup or by performing a cystocentesis, which passes a needle through the belly into the urinary bladder to remove a sample of urine.
Biopsy of the tumor. This is an essential procedure for definitive diagnosis of bone cancer. Because it is painful to biopsy bone, this procedure is done under anesthesia. Your veterinarian or a veterinary specialist such as an oncologist will insert a large needle into the affected area of bone to remove a core of tissue. The tissue sample is then submitted to a pathologist to determine the form/type of cancer. There is a minimal risk of fracturing the bone with this procedure, but because it is essential for the diagnosis, the risk is worth taking. Your pet is likely to be in pain after this procedure and pain medications are often administered. A patch may be placed on the skin to allow absorption of a constant level of narcotic.
Surgery. When it can be done, removal of the tumor en bloc, which means along with normal surrounding tissues, is the best way of dealing with hemangiosarcoma. Because bone hemangiosarcoma most commonly metastasises from another site, it is imperative that a thorough diagnostic test series be performed prior to surgery. Your veterinarian may refer you to a surgical specialist for these procedures. Surgery is the best means of removing the cancer and for most pets it results in abolishing the pain caused by the cancer. Depending on the extent of surgery, your pet may need to spend a few days in the hospital post-operatively where he can receive narcotic pain medications and fluid supportive care and be allowed to rest.
Chemotherapy. Because this cancer tends to spread very early, chemotherapy is usually prescribed. Chemotherapy usually starts in the postoperative period once healing has occurred and the sutures/staples have been removed. Chemotherapy drugs are typically given intravenously and their administration usually follows a set schedule of every three weeks for a total of four to six doses. Many different types of chemotherapy drugs are available, and your veterinarian is likely to refer you to a veterinary oncologist in your area who can advise you on treatment options.
One of the most commonly utilized drugs for hemangiosarcoma is adriamycin (Doxorubicin). However, every oncologist has a preference and may select certain drugs, or combinations of drugs, based on your pet's general health and the extent of disease. The common side effects include a decrease in white blood cell count approximately seven to 10 days after each treatment, nausea, vomiting and/or diarrhea. Each of these drugs may also have unique side effects which your oncologist will discuss with you.
Radiation therapy. This is a type of treatment in which a beam of radiation is directed at the tumor, resulting in palliative treatment or pain relief. It is a highly-specialized treatment and is available in select referral veterinary centers. It may be considered if your pet has existing conditions that disqualify him for surgery. Your cat will not experience side effects similar to those typically associated with radiation therapy in humans. The oncologist or radiation oncologist prescribing these treatments will discuss further details.
Pain medications. For those electing to not pursue any of the above treatments, the administration of both narcotic and non-narcotic anti-inflammatory drugs can help make your cat more comfortable.