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Hemangiosarcoma in Dogs

Dogs may get internal tumors that bleed.

Hemangiosarcoma in dogs is an aggressive, malignant cancer of the blood vessels. Dogs are more affected by hemangiosarcoma than any other species of animal. Because it affects blood vessels, this type of cancer is often associated with sudden internal bleeding, which can be life-threatening for your dog.

Is Hemangiosarcoma a Serious Condition in Dogs?

The severity of hemangiosarcoma depends on where it is found. This type of tumor can originate in several areas with the most common sites being the spleen, heart, skin, and liver. Only tumors found on the surface of the skin are considered to be curable and less serious than other areas. If the tumor is found early, complete surgical removal can cure your pet. If left to grow, cutaneous hemangiosarcoma can spread to other areas. This version of hemangiosarcoma is related to sun exposure and therefore is often seen in sparsely-haired areas (such as the abdomen) or in breeds with white hair. Certain breeds with white short fur, such as Dalmations or Pit Bull terriers, are more prone to developing cutaneous hemangiosarcoma.

Hemangiosarcoma found in other locations such as the spleen and heart, is always considered a very serious disease. The reason for this is that this tumor spreads early and quickly, so the cancer may be widespread before you notice any signs of illness in your dog. This form of hemangiosarcoma is termed "visceral."

Breeds Commonly Affected by Hemangiosarcoma

In general, hemangiosarcoma is a condition of large breed dogs that are middle-aged and older (6-12 years of age). The most commonly reported breeds associated with visceral hemangiosarcoma are German shepherds, Golden retrievers, Labrador retrievers, and Doberman pinschers. However, there is no confirmed hereditary component of the condition.

Signs of Hemangiosarcoma in Dogs

When signs do occur, they are usually the result of severe internal bleeding. At this time, your dog will become ill very suddenly and may show the following signs:

  • Pale or white gums
  • Profound weakness
  • Rapid heart rate
  • Rapid breathing rate
  • Collapse

These are all signs of circulatory shock, which occurs when the body loses a significant amount of blood quickly.

What Should I Do if I Think My Dog Is Showing the Signs Mentioned Above?

Again, these signs may be associated with any form of shock or lack of good blood flow and are always serious. You should seek veterinary care immediately either at your local veterinary clinic or an emergency clinic if it is after hours. You should expect your dog to be examined without delay on arrival and stabilized with treatments including an intravenous catheter, intravenous fluids, and occasionally pain medication. Your veterinarian will talk to you about tests that will need to be done right away to determine the cause of your dog's signs. These tests may include:

  • A blood test called a PCV, or hematocrit, to look at the percent of red blood cells.
  • X-rays to look for signs of abnormalities in the abdomen and chest.
  • An ultrasound to look for signs of free fluid or bleeding within the abdomen.
  • An EKG or electrocardiogram to look for abnormal heart rhythms that can develop from either blood loss or spread of the hemangiosarcoma to the heart.

Treatment of Hemangiosarcoma in Dogs

If hemangiosarcoma is found in the spleen (the most common location) or another abdominal organ in your dog, emergency surgery will generally be recommended to remove the organ and stop the bleeding. Depending on how much blood loss has occurred, a blood transfusion from another dog or a blood bank may be needed prior to surgery. Biopsy of the organ (submission of the tissue to a laboratory) will be necessary to accurately diagnose the tumor.

Your veterinarian will recommend evaluating your dog's heart for signs of hemangiosarcoma as well. Reports have cited that up to 25% of dogs with abdominal hemangiosarcoma also have involvement within the heart. This is important to know prior to pursuing surgery as it will affect the long term plan and may be a factor for your pet under anesthesia.

Because this type of cancer is so aggressive, treatment is extensive. For owners that want to pursue all options, surgery is followed by chemotherapy. Even with this extent of care, it is not anticipated that the hemangiosarcoma will be cured, but the return of the tumor may be delayed. Because the long-term prognosis for hemangiosarcoma is poor, many owners elect euthanasia for their pets rather than pursue treatment.

Prevention of Hemangiosarcoma in Dogs

Avoiding prolonged exposure to the sun can decrease the likelihood of the development of the skin form of hemangiosarcoma. However, there is no way to prevent the development of visceral hemangiosarcoma. The goal is to diagnose the condition as early as possible in hopes that surgery can be attempted before the tumors grow large enough to spread or rupture. Your veterinarian can discuss with you ways to look for visceral forms of hemangiosarcoma which may include X-ray or ultrasound. These tests may be recommended in certain breeds as they reach middle age, even if the dog is not showing any clinical signs.

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