Hemangiosarcoma, the deadly cancer in dogs | Dr. Justine Lee, DAVECC, DABT, Board-certified Veterinary Specialist

Posted by justinelee in Animal Safety, Blog, Pet Health

If your dog was just diagnosed with hemangiosarcoma, here’s what you need to know.

As an emergency critical care veterinary specialist, this is my most hated type of cancer in dogs (and rarely, cats). That’s because it comes on suddenly, and results in internal bleeding. It’s so devastating to pet owners, as they think their dog is fine one day, and then ends up being diagnosed with cancer in the ER based on one day of sudden clinical signs.

So, what do you need to know?

Hemangiosarcoma, often abbreviated HSA, is a very malignant, aggressive, deadly vascular endothelial tumor in dogs (and less commonly, in cats). HSA is one of the most common types of cancer seen in dogs; some estimate that HSA accounts for 5-7% of all the types of cancer seen in dogs in veterinary medicine.1

Hemangiosarcoma spreads aggressively throughout the body, particularly to blood-loving organs. HSA is highly metastatic (e.g., spreads easily), and often affects the following organs or tissues:

• Spleen
• Liver
• Right atrium of the heart
• Skin
• Lungs
• Mesentery (the thin sheet of tissue in the abdomen attaching the intestines together)
• Diaphragm

As HSA has a propensity for vascular tissue, the cancer starts growing in blood vessels and results in large tumors and masses that can acutely rupture, resulting in internal bleeding. Clinically, the most common location where we see this rupture (and secondary internal bleeding) is on the spleen, resulting in a hemoabdomen (e.g., an abdominal cavity full of blood) and signs of severe shock. Unfortunately, by the time signs of internal bleeding have occurred, the cancer is quite advanced and has already metastasized (e.g., spread microscopic cancer cells) throughout the body.

Unfortunately, if you have a golden retriever, this is one of the top cancers that we can see in older Goldies. Middle-aged to older-dogs are more predisposed to cancer, as are certain breeds of dogs. Other breeds that have a higher incidence of this type of cancer are:

• Golden retrievers*
• German shepherds
• Boxes
• Great Danes
• English Setters
• Portuguese water dogs
• Bernese Mountain dogs
• Skye terriers
• Pointers
• Mixed breed dogs
*Estimated to occur in 1 of every 5 Golden retrievers1

So what signs will my dog show with hemangiosarcoma?

The most frustrating problem with hemangiosarcoma is that pets typically don’t show any clinical signs of HSA until the tumor has ruptured, resulting in acute internal bleeding. Unfortunately, hemangiosarcoma is considered “indolent” as it grows– in other words, this cancer grows slowly and painlessly;1 therefore, pets don’t demonstrate any signs that we can observe to detect it earlier until it ruptures.

Once HSA has ruptured, clinical signs include:
• Lethargy/weakness
• Collapse
• Inability to get up
• Pale white gums
• A racing heart rate
• Constant panting
• Exercise intolerance
• Vomiting
• Walking drunk
• Excessive thirst
• A distended abdomen
• Swelling or mass of the skin or over the body
• Weight loss
• Acute death

The diagnosis of hemangiosarcoma is based on physical examination findings consistent with internal bleeding (e.g., palpating fluid in the abdomen, muffled heart sounds, etc.) and hemorrhagic shock (e.g., an elevated heart rate, low blood pressure, pale gums). Additional diagnostic tests necessary to aid in the diagnosis of HSA include the following:

• Blood work such as a complete blood count (CBC), biochemistry panel, and coagulation panel (e.g., clotting test) to evaluate the red blood cells, white blood cells, platelets, clotting function, electrolytes, kidney and liver function. Findings consistent with HSA typically include the presence of an anemia, low protein, low platelet count, and abnormal clotting tests.
• X-rays of the chest and abdomen to look for the presence of a mass on the spleen, abnormal fluid in the abdomen, or metastasis spread to the lungs.
• Ultrasound (which is different than x-rays, as it lets us look at the architecture of the organ, not just the size) of the abdomen to look for the presence of a mass, internal bleeding or evidence of cancer spread (typically to the liver).
• Echocardiogram (ultrasound of the heart) to look for the presence of hemangiosarcoma on the right atrium of the heart, along with abnormal fluid in the pericardial sac.
• Electrocardiogram (EGG) (measuring the rhythm of the heart) to look for the presence of abnormal arrhythmia (e.g., ventricular premature contractions) commonly seen with HSA
• Biopsy or aspirates of the mass. This is typically done at surgery, where the whole mass (e.g., spleen) is removed. Unfortunately, biopsies or aspirates done by ultrasound pre-surgery are often not diagnostic, as the large presence of normal red blood cells in these vascular organs often interfere with interpretation of accurate results.

So what can we do to treat it if your dog was just diagnosed with hemangiosarcoma?
Treatment includes a visit to your veterinarian – even if it’s in the middle of the night in the veterinary ER. That’s because dogs present with internal bleeding and need life-saving stabilization with intravenous (IV) fluids, blood transfusions, blood pressure and ECG monitoring, and symptomatic supportive care. Once your dog has been stabilized, surgery is recommended to to remove what’s actively bleeding (e.g., typically the spleen) – however, this should only be considered if cancer spread (e.g., metastasis) isn’t present. If cancer spread is already present – in other words, already spread to the lungs, the liver, etc., the prognosis is grave.

Unfortunately, even with aggressive therapy (e.g., surgery, chemotherapy, etc.), the prognosis for hemangiosarcoma is still poor, with the mean survival time ranging from as little as 2 weeks to several months. With surgery alone, the lifespan is typically considered to be approximately 1-3 months,2,3 while with surgery and chemotherapy together, the mean survival time is approximately 4-6 months.3 Unfortunately, < 50% of dogs treated with surgery and chemotherapy survive more than 6 months,1 and less than 10% of dogs diagnosed with HSA survive to 1 year. There are some newer medications (like eBAT) and holistic options (like I’m-Yunity mushrooms and Yunnan Baiyao) out there, so stay tuned and talk to a veterinary oncologist (specialist) about this! #ad

Prevention
Unfortunately, there are no obvious steps to prevent cancer in dogs in cats. That said, here are a few tips that may save your pets life.

• Routine veterinary visits – as your pet ages, the risk for cancer increases. A twice-a-year exam for a physical examination is a must, as it allows for earlier detection of medical problems.

• Talk to your veterinarian about skipping the vaccines as your pet ages, and performing screening blood work – or even x-rays of the abdomen – instead. If abnormalities are found early, they can be treated earlier. This is particularly important in Golden retrievers over 6-7 years of age, as they have a higher risk for HSA.

• If pre-screening tests reveal something suspicious, talk to your veterinarian about aggressive diagnostic workup and treatment, including ultrasound (by a board-certified radiologist or internist) and possible splenectomy (e.g., removing the spleen). I’m aggressive with splenectomy in predisposed dogs (e.g., Golden retrievers, German shepherds); in other words, if your middle-aged dog undergoes a “routine” abdominal surgery (e.g., for a foreign body removal), I’d actually advocate about potentially removing the spleen at the same time. Sounds heroic and extreme, but I did this for my own dog to minimize the risk after he was diagnosed with splenic masses that were found on routine geriatric ultrasound (Thankfully, the splenic masses turned out to be benign, and he recovered from surgery well).

• Report it to your breeder. If your dog was diagnosed with cancer, make sure your breeder knows so they can track the incidence and evaluate whether or not to breed that same breeding pair back. As we veterinarians suspect there is an inherited association with this cancer, we want to help minimize the risk.

• Consider a splenectomy in your dog? If you own a middle-aged to older Golden retriever who happens to go to abdominal surgery for something else (e.g., like a GDV, intestinal surgery for a bone stuck in the abdomen, etc.), talk to your veterinarian about having the spleen removed at the same time to potentially help prevent this type of cancer. Who knows if the cancer will end up growing somewhere else, but this is something that I would consider. I did this in my own older pit bull dog.

References:
1. http://www.modianolab.org/cancer/cancer_hemangiosarcoma.shtml, Accessed November 3, 2013.
2. Wood CA, Moore AS, Gliatto JM, et al. Prognosis for dogs with Stage I or II splenic hemangiosarcoma treated by splenectomy alone: 32 cases (1991-1993). J Am Anim Hosp Assoc 1998 Sep-Oct;34(5):417-21.
3. Hamilton TA. Hemangiosarcoma, Spleen and Liver. In Blackwell’s Five-Minute Veterinary Consult: Canine & Feline. Eds. Tilley LP, Smith FWK. 2007, 4th ed. Blackwell Publishing, Ames, Iowa. pp. 582-583.