Margaret C. Saiki, D.V.M.,
Over 20 Years of Experience!
Former Medical Director
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Hemangiosarcoma: A common highly malignant cancer of large breed dogs

Hemangiosarcoma: A common highly malignant cancer of large breed dogs


 Margaret Saiki


As a mobile veterinarian my blogs have touched on subjects which I see commonly in my veterinary house call practice. In keeping with this theme this blog will focus on a common cancer seen in large breed dogs, hemangiosarcoma and the dilemmas owners face when their pet’s develop this tumor.



Unfortunately hemangioscarcoma (HSA) is a common malignant, highly malignant tumor in the dog and especially any large breed dogs. One in 5 German shepherd dogs, golden retrievers and Labrador retrievers will develop HSA.

HSA can occur in any tissue that has blood vessels because it arises from a cell in the blood vessel called the endothelia cell. As you can imagine this tumor is very vascular and bleeding is a common occurrence. Being vascular, it spreads (metastasize) easily. The most common sites for this tumor to occur in the dog are the spleen (50-65%), heart (3-25%), under the skin (12-17%) and liver (5-6%).

At the time of presentation to the veterinarian, 80% have spread or metastasized. The most common tissues for this tumor to spread to are, the liver, tissues surrounding the internal organs and liver although any tissue of the body.

It is beyond the scope of this blog to detail this cancer in detail. For a more information about hemangiosarcoma in dogs please go to the highlighted link. (Wikipedia) I would like to comment on what is most commonly seen and the issues surrounding this situation.


Most common problem seen

In a pet hospice care perspective, this cancer presents many management issues all depending on which tissues of the body are effected. For the purposes of this blog article, I will be discussing the most common problem we see concerning this tumor.

As stated above HSA occurs 50-65% of the time in the spleen. The spleen is a highly vascular organ responsible for filtering old red blood cells, holding them in reserve and plays a role in the body’s immune system.

HSA tumors can grow to be quite large and cause bleeding into the abdomen because of its friable nature. If large blood loss occurs, your dog can become weak, lethargic and pale.  Uncontrolled bleeding will result in death. If the bleeding into the abdomen stops on its own patients can gradually reabsorb some of the lost reds cells and gradually over a few days gain strength. In fact, it is not uncommon for these patients to present with to their veterinarian with a history of intermittent episodes of weakness with gradual recovery.


Survival time

Survival is quite short after diagnosis. Without treatment it is usually 20-60 days with a 1- year survival of less than 10 %. Surgery plus chemotherapy increases survival rates slightly to 141-179 days with a 1- year survival of 10% or less. With these statistics it mind, many owners do not pursue treatment and elect pet hospice care or more commonly humane pet euthanasia. Survival times can better be predicted if the tumor is fully staged with lab work, ultrasounds and x-rays. There is no cure for HAS at this time.


The Owner’s dilemma

Unfortunately, it is difficult to predict when a fatal bleed will occur. Owners are left with the difficult decision of when to consider a humane pet euthanasia. They are torn between having more time to spend with their beloved pet and not wanting to risk having them die because of a massive bleed. In the between the episodes of bleeding and recovery, their dogs seem to have a good quality of life.

Palliative care protocols for these patients are limited. There are palliative care protocols for HAS using oral Yunan- Paio; metronimic chemotherapy with HDAC inhibitor, masitinib, T-cyte injections or IV carboplatin every 21 day. Consult a veterinary cancer specialist for this palliative care treatment option.

The decision when to consider a humane euthanasia for your pet with HAS therefor depends on being able to detect when bleeding is occurring.


What owners should know if their dog has HSA and have elected not to treat:

Learn to the best of your ability to evaluate the vital signs of their dogs. These vital signs should include heart rate, respiratory rate, pulse quality, color of the gums and capillary refill time (crt). Capillary refill 



·        time is how fast it takes the color of the gums to return back to normal after being pressed on. Ask your veterinarian to help you learn how to evaluate your pet’s vital signs. Learning these signs will be a clue to help you know when your dog is in the middle of an abdominal bleed.


·        In general if there is large blood loss you will notice:


Increase in heart rate


Increase in respiratory rate


Decrease in redness of the gums or even pallor


Prolonging of the capillary refill time


Decrease in the quality of the pulse strength


Some astute owners can detect an enlarging and pendulous abdominal area.


Generalized weakness, not eating, not drinking, decrease in general alertness


·        If you suspect bleeding maybe occurring try wrapping the abdominal area with a towel and tape in order to apply pressure and hopefully stop the bleeding event.




Hemangiosarcoma is a highly malignant, aggressive and difficult to treat. Electing to perform surgery to remove the bleeding organ such as the spleen and adding chemotherapy can prolong survival, but for only a few months (5-6).  Electing a loving at home pet euthanasia, is an alternative many owners. It is this practices hope to help your pet pass peacefully at home. 




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