Spleen Tumors in Dogs

Benign vs Cancerous Splenic Masses

Ultrasound often can't tell a hematoma from hemangiosarcoma, and even enlarged lymph nodes or nodules in the liver can turn out to be benign.^11,12 Vets advise against giving a final prognosis until the removed spleen has been examined.¹²

Signs of a Spleen Tumor

Many splenic masses cause no signs and are found on an exam or ultrasound for something else.^10,2 When there are signs, they can be vague: reduced appetite, weight loss, tiredness, weakness or episodes of fainting.⁴ A bleeding mass causes sudden weakness, pale gums, fast breathing, a swollen belly and collapse.^4,8 Smaller bleeds cause anemia with subtle signs such as pale gums, weakness and tiredness.¹³

Hemangiosarcoma "almost always goes undiagnosed until the late stages," because it can grow for a long time without obvious signs.¹³

Which Dogs Are at Risk?

Splenic masses are most common in older dogs. Hemangiosarcoma is more common in large breeds, especially German Shepherds, Golden Retrievers and Labrador Retrievers.^8,9,15 In a 2016 study, it made up 65% of splenic cancers in dogs over about 61 lb, compared with 46% in smaller dogs.¹⁵ In a 2024 study, all 6 German Shepherds with splenic masses had hemangiosarcoma.²

Diagnosis

• Ultrasound finds the mass and any bleeding in the belly (hemoabdomen).^1,9
• Blood tests, clotting tests and chest X-rays check for anemia and spread.⁹
• A heart scan (echocardiogram) may be advised, because hemangiosarcoma can also involve the heart.^11,16
• Splenectomy with lab examination gives the diagnosis. Removing the spleen is usually preferred over a biopsy.^4,1

Avoid blood thinners and NSAID-class pain relievers before surgery unless your vet says otherwise.⁹

Splenectomy: Surgery and Recovery

Dogs with bleeding are stabilized first with fluids and sometimes a blood transfusion.⁴ Most stay in the hospital for 24 to 48 hours, with heart monitoring, because irregular heart rhythms are common after surgery and usually settle within a day or two.^4,12 Other risks include bleeding and pancreatitis, and complications are higher after emergency surgery.^4,7

• Leash walks only, with no stairs or jumping, for about 2 weeks^4,7
• Stitches out in 10 to 14 days⁷
• Approximate US cost: $1,500 to $9,000 or more (PetMD, 2025), higher for emergency surgery⁷

The spleen helps fight infection and filter old red blood cells, but dogs tolerate losing it very well.⁶ Some vets advise extra care with tick prevention and infection risks afterward.⁷

Outlook and Life Expectancy

For benign masses, surgery is usually curative.^1,4 In a 2025 study of dogs with bleeding benign masses, 71% were still alive at the end of follow-up, at a median of about a year.⁵

For splenic hemangiosarcoma, most dogs live about 1 to 3 months with surgery alone. Adding chemotherapy extends this to about 4 to 8 months on average, and up to about 1 in 5 dogs is alive a year later.^14,1,4,16 Without surgery, a dog with a ruptured hemangiosarcoma may live only days to a couple of weeks.¹³ See hemangiosarcoma in dogs for treatment details.

Making Decisions in an Emergency

Owners often have to decide quickly when a dog collapses from a bleeding spleen. Surgery can be lifesaving if the mass is benign, while euthanasia is a kind choice if hemangiosarcoma is likely to have spread or surgery isn't possible. Euthanasia is a medically and ethically acceptable option, and the decision is yours to make.^17,12 Repeated collapse, pale gums, labored breathing or a swollen belly that returns are signs it may be time to talk about saying goodbye.^8,18 See quality of life and when to say goodbye.

Frequently Asked Questions

Is every spleen tumor in a dog cancer?

No. Masses found by chance are usually benign. Masses that have bled are more often cancer.

How long can a dog live with a spleen tumor without surgery?

It depends on the type. A benign mass may never cause trouble or may bleed. A ruptured hemangiosarcoma is often fatal within days to weeks.

Is a spleen tumor painful for dogs?

A bleeding spleen makes dogs weak and uncomfortable. Ask your vet about pain relief.

What is hemoabdomen?

Bleeding into the belly. In dogs with a splenic mass, it makes cancer more likely.

Can a dog live without a spleen?

Yes. Dogs usually live normal lives after splenectomy.