Pet Health Library

Background

Hemangiosarcoma (HSA) is a highly aggressive cancer in the blood vessels – more specifically, in the soft tissue lining of the blood vessels. It is highly likely to metastasize across the body and is often deemed “the silent killer,” as the pet may not show any clinical signs until the condition is in its later stages. These tumors can occur anywhere in the body, but HSA usually develops in the spleen, heart, or skin.

The most common form of HSA in dogs occurs in the spleen, known as splenic HSA. This article focuses on splenic HSA in dogs.

Risk Factors

• Age – Splenic HSA usually affects older dogs, but can develop in younger dogs in rare instances.
• Breed – Splenic HSA is more common in certain breeds, such as German Shepherds, Golden Retrievers, and Labrador Retrievers. However, any dog of any size can develop splenic HSA.

Signs

Signs may vary depending on the stage of the tumor. In many cases, the pet will exhibit non-specific signs of illness such as lethargy or weakness, reluctance to exercise, and a decreased appetite.

With HSA there is a risk of the tumor rupturing and bleeding inside the body. This is a life-threatening scenario in which the pet may present severe clinical signs such as:

• Pale gums (anemia)
• Severe weakness
• Rapid or difficulty breathing
• Sudden collapse
• Sudden death

Diagnosis and Treatment

A biopsy of the tumor is needed to diagnose splenic HSA. However, suspicion is high when a splenic mass is identified through the use of imaging technologies (x-rays, ultrasounds, and CT scans) in a dog with the clinical signs described above.

The surgical removal of the spleen (a splenectomy) is both a diagnostic test and a treatment, and is often an emergency procedure as it stops the bleeding. After being removed, the spleen is submitted for a biopsy to confirm a diagnosis. Surgery is the most important treatment, but chemotherapy can extend the life of some dogs with HSA.

The prognosis for splenic HSA can be anywhere from mere days to around 6 months and highly depends on the stage of the cancer. On average, the life expectancy following surgery alone is around 3 months, and around 6 months if followed by chemotherapy.

Canine hemangiosarcoma is an area of active research and your veterinarian may be able to refer you and your dog to a clinical trial.

Prevention

Like with many cancers, the cause of splenic HSA is unknown. Because of this, it cannot be prevented.

If your pet is diagnosed with splenic HSA, schedule a consultation with a board-certified veterinary oncologist. They can create an individualized treatment plan depending on the stage of the cancer in your pet.