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Writer's pictureMargo Murillo, DVM

Hemangiosarcomas in Dogs and Cats


Golden Retriever and German Shepherd laying next to each other in a field

Hemangiosarcoma is a type of aggressive cancer that affects the cells lining blood vessels. While it is more common in dogs, particularly certain breeds, it can also occur in cats, though much less frequently. Understanding this condition can help pet owners recognize symptoms early, discuss treatment options with their veterinarian, and make informed decisions for their pet’s care.


What is Hemangiosarcoma?

Hemangiosarcoma is a malignant cancer that arises from the endothelial cells, which line the interior of blood vessels. This type of cancer is notorious for its rapid and aggressive spread, often involving organs with rich blood supplies, like the spleen, liver, heart, and skin. Since hemangiosarcoma is highly vascular, it is prone to rupture, leading to internal bleeding which can be life-threatening.


Dog Breeds Commonly Affected by Hemangiosarcomas:

  • German Shepherds

  • Golden Retrievers

  • Labrador Retrievers

  • Portuguese Water Dogs

  • Boxers


Where Does Hemangiosarcoma Occur?

Hemangiosarcoma most commonly affects:

  1. Spleen - This is the most common site in dogs, and splenic hemangiosarcomas often go unnoticed until the tumor ruptures, causing internal bleeding and sudden collapse.

  2. Liver - Tumors in the liver are similar to those in the spleen in that they can rupture and cause bleeding.

  3. Heart (Right Atrium) - When it occurs in the heart, specifically the right atrium, hemangiosarcoma can cause pericardial effusion (fluid around the heart), leading to symptoms like collapse, difficulty breathing, and lethargy.

  4. Skin and Subcutaneous Tissue - Skin hemangiosarcomas may appear as red or dark lumps on the surface of the skin. Though less dangerous than internal tumors, they can still metastasize or bleed profusely.


Symptoms of Hemangiosarcoma

Symptoms vary depending on the location of the tumor but often include:

  • Lethargy or sudden weakness

  • Pale gums (anemia from internal bleeding)

  • Rapid breathing or difficulty breathing

  • Distended abdomen or bloating

  • Collapse episodes or fainting

  • Visible masses or growths on the skin

Often, hemangiosarcoma remains asymptomatic until the tumor ruptures, making early detection difficult.


Diagnosis of Hemangiosarcoma

A veterinarian may use various diagnostic tools to detect hemangiosarcoma:

  • Ultrasound or X-rays: Imaging is helpful in identifying the presence and location of a tumor.

  • Echocardiogram: For heart involvement, an echocardiogram can detect fluid around the heart and assess cardiac tumors.

  • Bloodwork: Blood tests may reveal anemia, changes in liver enzymes, or other signs indicating internal bleeding.

  • Fine-needle Aspirate or Biopsy: If a mass is accessible, a sample may be taken to confirm the diagnosis.


Treatment Options for Hemangiosarcoma

Treatment for hemangiosarcoma depends on several factors, including the location and stage of the tumor, as well as the overall health of the pet. Options include:

  1. Surgery: Surgery is often the first line of treatment, particularly for splenic hemangiosarcomas. The spleen is removed in a procedure called a splenectomy, which can provide immediate relief if bleeding is present. However, surgery alone is rarely curative, as metastasis often occurs before the primary tumor is identified.

  2. Chemotherapy: Given the high rate of metastasis, chemotherapy is commonly recommended after surgery. Doxorubicin, a chemotherapy drug, is often used to extend survival time. Chemotherapy may also be recommended for tumors that cannot be surgically removed, such as those in the heart.

  3. Immunotherapy: Newer treatments like immunotherapy, including therapies using monoclonal antibodies, aim to stimulate the immune system to target cancer cells.

  4. Palliative Care: For cases where surgery or chemotherapy is not possible, palliative care may focus on maintaining quality of life and managing symptoms, such as pain and bleeding.


Prognosis for Hemangiosarcoma

The prognosis for hemangiosarcoma is guarded, primarily due to its aggressive nature and the tendency to metastasize early. Life expectancy can vary:

  • With surgery alone: Dogs with splenic hemangiosarcoma that undergo surgery may survive an additional 1–3 months on average.

  • With surgery and chemotherapy: Some dogs may live 6–9 months or longer, depending on the individual case and how well they respond to treatment.

  • Without treatment: Prognosis is typically very short, as internal bleeding and metastasis quickly lead to life-threatening complications.

For cats, hemangiosarcoma is less common, but the prognosis is also generally poor once diagnosed due to its aggressive nature.


Prevention

Unfortunately, there is no known prevention for hemangiosarcoma, though some studies suggest that limiting sun exposure may help prevent skin hemangiosarcoma, especially in light-colored or thin-coated dogs. Routine wellness exams and veterinary check-ups can help monitor overall health, and prompt attention to unusual symptoms can potentially catch internal masses before they become problematic.


Hemangiosarcoma is a challenging diagnosis for any pet owner, but knowing the symptoms and treatment options can help guide the journey ahead. Working closely with a veterinarian to assess the options for your pet’s specific case will ensure they receive the most compassionate and effective care possible.


AI used to aid with article creation.

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