Hemangiosarcoma

Taken from Oncology Outlook

Hemangiosarcoma (HSA) of the Spleen – Part 1

The dog was okay then he suddenly collapsed. It's a dramatic scene all too familiar to the emergency veterinarian: the emergency visit, the urgent assessment and life saving decisions to make.

In this episode the dog was Marty, a 19-year-old, 90 lb. collie. He was weak, in shock, had a big belly and pale tongue. The culprit, a bleeding spleen. The surgical removal of this useful but expendable organ is the solution. However, ruptured splenic mass has an 80% chance of being cancer (Hemangiosarcoma). Life expectancy with surgery is four months, give or take, if the biopsy shows cancer.

In order to make a diagnosis and clear recommendations a veterinarian looks at blood tests and x-rays of the chest and abdomen. A transfusion may be indicated. If possible, an ultrasound of the abdomen and heart is performed. Occasionally a sample can be obtained to define the mass. These additional tests may identify and determine the extent of the condition and help predict the long-term benefit of exploratory surgery.

While the 80% chance of cancer is a grim statistic, Marty's owner chose surgery with the prospect of four precious months and a 20% chance that his tumor was benign. In Marty's case that was the right decision. We're delighted to report the recent celebration of Marty's 22nd birthday.

The warning signs of splenic tumors in dogs are easy for owners to overlook. Pets with enlarged spleens are less active. The lips and tongue may appear pale due to low red blood cell count (anemia). In advanced cases of splenomegaly (enlarged spleen) the abdomen appears distended or enlarged but owners may think their dog just looks pregnant or fat. They don't see cause for alarm if the dog eats and acts well enough..

Splenic cancer represents 2% of all tumors in dogs. Some of the tumors get very large and cause the spleen to bleed or rupture. Big dogs, especially German Shepherds, Golden Retrievers and Labrador Retrievers are commonly affected. Schnauzers, a small breed, are also at greater risk. Older dogs are more commonly affected with benign splenic tumors (hyperplastic nodules) as in Marty's case. There is no known cause for Hemangiosarcoma, but genetic factors are obvious due to breed prevalence.

The cells that become malignant in HSA are the endothelial (blood vessel) cells. These cells create the circular walls of blood vessels. Genetic mutations spark uncontrolled growth of cells and the result is cancer. In HSA, endothelial cells multiply uncontrollably and develop into huge, cavernous, blood filled tumors. Since blood vessels exist in every tissue, HSA can originate as a primary tumor in most tissues, but the heart (right atrium), skin, subcutaneous tissue and muscle are the most common primary sites after the spleen. With the exception of solar induced cutaneous HSA found in Whippets and other dogs with unpigmented skin, HSA spreads rapidly to lungs, liver and local tissues via direct extension and the blood stream. It is rare in cats.

Hemangiosarcoma is reason enough in my opinion for all German Shepherd owners to consider an ultrasound screening for their senior dogs every six to eight months. Ideally we would like to see serological screening tests on the market that could reliably reveal insidious cancer in pets.

Treatment of hemangiosarcoma warrants a thorough discussion and will be addressed in Oncology Outlook (HSA, Part II) in a following issue of VPN.