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Updated May 7, 2020 – Hemangiosarcoma is a common and deadly cancer of dogs. The cancer tends to grow rapidly and spread, rarely giving the owner any clue their dog is harboring a deadly disease – until it suddenly strikes.

Knowing more about how this cancer develops and learning to recognize the subtle signs of the disease is important for owners, not only to spot a potential problem, but also be prepared if hemangiosarcoma affects their dog.

Hemangiosarcoma arises in sites with a rich blood supply

Hemangiosarcomas begin with uncontrolled growth of the cells lining blood vessels. Because of their abundant blood supply, the heart and spleen are the two most common sites where this type of tumor is found. This predilection for growth in blood-rich areas is the reason these tumors are so deadly. Hemangiosarcomas can suddenly rupture, causing massive blood loss, and forcing owners and veterinarians to make difficult decisions within minutes of diagnosis.

Hemangiosarcoma is a disease of larger breed, older dogs

Hemangiosarcoma most commonly affects:

  • Middle-aged to older dogs
  • German shepherds, golden retrievers, Portuguese water dogs and Labrador retrievers
  • Slightly more males than females (in some studies)

Unfortunately, no clinical signs (symptoms) are classic for hemangiosarcoma other than sudden, profound, internal bleeding. Other clinical signs sometimes reported by owners include:

  • Intermittent lethargy or fatigue
  • Anorexia
  • Panting
  • Sudden collapse
  • Sudden death

Most pet owners are quick to act in cases of sudden collapse and time is of the essence in cases of hemangiosarcoma. These are true medical emergencies and many patients require immediate surgery to remove the bleeding mass (if possible), followed by supportive care to survive.

Long-term survival statistics are bleak

Even when a tumor is quickly detected and removed, the outlook for dogs with hemangiosarcoma is grim. Statistics show that:

  • Average survival time with surgery alone is one to three months
  • Average survival time with surgery and chemotherapy is five to seven months
  • 90% of dogs are deceased one year post-diagnosis despite surgery and chemotherapy with almost 100% mortality two years post-diagnosis

Survival times have remained static for nearly 30 years, and new treatments are desperately needed. This is where Morris Animal Foundation comes in.

Morris Animal Foundation is trying to improve the odds for dogs with hemangiosarcoma

Morris Animal Foundation has invested more than $3 million over 20 years of research to improve the quality and duration of life for dogs diagnosed with hemangiosarcoma.

Our funded research has focused on:

  • Disease basics – understanding the basic biology of hemangiosarcoma may open the way to new diagnostics, treatments and prevention
  • Overcoming chemotherapy resistance – understanding why hemangiosarcomas become drug resistant could improve treatment success as well as discover new chemotherapy agents
  • Genetic links – studying breeds commonly affected by hemangiosarcoma could lead to new diagnostic testing and clues to the role genetics play in the development of  this disease

Golden Retriever Lifetime Study

Hemangiosarcoma is an important cancer of golden retrievers and is one of several cancers of special interest to the Foundation’s Golden Retriever Lifetime Study. We’re monitoring and collecting extra tissue and other biologic samples from all dogs in our cohort diagnosed with hemangiosarcoma. In addition to samples collected at the time of diagnosis or death, we have banked samples on affected dogs dating back years that may point to risk factors associated with this cancer. Our hope is that researchers will be able to use these samples to develop early diagnostic tests as well as understand possible genetic links to this deadly disease.

We need you support!

Morris Animal Foundation is a global leader in funding the cancer research needed to help our pets live longer, healthier lives.

Our Stop Cancer Furever campaign runs May 1 through June30 to raise awareness of and funds for cancer research. This year, we’re excited to announce that, thanks to a generous gift from the Petco Foundation and Blue Buffalo Company, all gifts will be matched, up to $100,000, through June 30. That means your donation will go twice as far toward providing funding to stop pet cancer and save lives. Thank you!


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