What causes hemangiosarcoma in dogs?

The exact cause is unknown, but genetic factors and breed predispositions play a role. It often affects middle-aged to older dogs.

Can hemangiosarcoma be cured?

While surgery and chemotherapy can extend life expectancy, hemangiosarcoma is often not curable due to its aggressive nature and tendency to spread.

What are the signs of hemangiosarcoma?

Signs include sudden collapse, pale gums, weakness, and abdominal swelling. These symptoms are due to internal bleeding from the tumor.

DOGS · Condition guide

Hemangiosarcoma in dogs: what real veterinary cases show

Appetite & weightDogs

Hemangiosarcoma is a type of cancer that arises from the cells lining blood vessels, often affecting the spleen, liver, and heart in dogs. It is an aggressive cancer known for causing sudden internal bleeding, and it is more common in certain breeds like German Shepherds and Golden Retrievers.

Owners often first notice signs like sudden weakness or collapse, pale gums, and a distended abdomen due to internal bleeding. Early detection is crucial because the condition can rapidly become life-threatening, requiring immediate veterinary attention.

What vets typically check for

Physical examination and history taking to assess symptoms.
Ultrasound or X-rays to identify tumors in the spleen or liver.
Blood tests to evaluate anemia and overall health status.
Biopsy or surgical exploration to confirm diagnosis.
Surgical removal of the tumor and chemotherapy as treatment options.

Not a replacement for veterinary care. Use this to walk into the conversation prepared, not to self-diagnose.

Real cases from the veterinary literature

Peer-reviewed reports our semantic search surfaces for Canine hemangiosarcoma. Click into any case for the full abstract — or run a personalised search with your pet's exact details.

OncoCan: a liquid biopsy assay for cell-free DNA quantification in canine plasma to support cancer prognosis.
Frontiers in veterinary science · 2026 · Spain
A study looked at a new blood test called OncoCan that measures cell-free DNA (cfDNA) in dogs to help detect cancer early. Researchers tested samples from 83 dogs with different types of tumors and found that those with cancer had significantly higher levels of cfDNA compared to healthy dogs. The test showed high accuracy for certain blood cancers and moderate accuracy for othe
Surgical timing in dogs with spontaneous hemoperitoneum is not related to blood product use, incidence of adverse events, or survival to discharge.
Journal of the American Veterinary Medical Association · 2026
A group of dogs with spontaneous hemoperitoneum (bleeding in the abdomen) underwent surgery at different times after showing symptoms. The study found that whether the surgery was done urgently, within 12 hours, or later did not affect the chances of complications or survival after surgery. Most dogs, about 94%, survived and went home regardless of when they had surgery. The re
Surgical treatment and outcome of intracranial hemangiosarcoma in two dogs: case series.
Frontiers in veterinary science · 2026 · United States
A 7-year-old male dog experienced seizures and was diagnosed with an intracranial hemangiosarcoma, a type of cancer that forms in blood vessels in the brain. After an MRI confirmed the mass, the tumor was surgically removed. One dog did not receive further treatment and was euthanized 87 days later due to declining quality of life. The other dog received chemotherapy but had a
Prevalence and Risk Factors for Survival in Dogs and Cats With Cancer Admitted to the ICU.
Journal of veterinary emergency and critical care (San Antonio, Tex. : 2001) · 2026 · United Kingdom
A group of 114 dogs and 38 cats with cancer were admitted to the ICU, often due to breathing problems or heart issues. The study found that about 57% of these pets survived their hospital stay, but only 31% were still alive three months later. Pets that received surgery or chemotherapy had a better chance of survival compared to those who did not. Unfortunately, most of the pet
Cytology and histopathology have poor to fair agreement for determination of neoplastic or nonneoplastic lesions in dogs with splenic masses or nodules.
Journal of the American Veterinary Medical Association · 2026 · United States
A group of 33 dogs with splenic masses or nodules underwent two types of tests—cytology (cell analysis) and histopathology (tissue analysis)—to determine if the growths were cancerous or not. The results showed that the two tests agreed only about half the time, with cytology being more accurate for identifying cancerous growths. In cases where cytology suggested a possible can
Epidemiology of Four Major Canine Tumours in the UK: Insights From a National Pathology Registry With Comparative Oncology Perspectives.
Veterinary and comparative oncology · 2026 · Spain
A study found that certain breeds of dogs are more likely to develop specific types of cancer, including mast cell tumors, osteosarcoma, melanoma, and hemangiosarcoma. For example, Bulldog-related breeds and Retrievers have a higher risk for mast cell tumors, while Rottweilers and Shar Peis are more prone to melanoma. Neutered dogs, especially females, showed higher odds of dev

Run a personalised search for your pet →

Frequently asked questions

What causes hemangiosarcoma in dogs?: The exact cause is unknown, but genetic factors and breed predispositions play a role. It often affects middle-aged to older dogs.
Can hemangiosarcoma be cured?: While surgery and chemotherapy can extend life expectancy, hemangiosarcoma is often not curable due to its aggressive nature and tendency to spread.
What are the signs of hemangiosarcoma?: Signs include sudden collapse, pale gums, weakness, and abdominal swelling. These symptoms are due to internal bleeding from the tumor.

Browse all dogs guides