Dog spleen tumor life expectancy: benign vs malignant

Life expectancy with a spleen tumor depends almost entirely on whether the mass is benign or malignant, and that usually cannot be known for certain until the spleen has been removed and examined by a pathologist. A dog whose mass turns out to be benign, such as a hematoma or nodular hyperplasia, typically goes on to a normal lifespan after surgery. A dog with hemangiosarcoma, the most common malignant spleen tumor, commonly lives one to three months after surgery alone and around four to six months with surgery and chemotherapy.

Without surgery, a benign mass may sit quietly for a long time or may bleed. A malignant mass that has already bled usually bleeds again, often within days to weeks. All of these are commonly reported ranges with a lot of variation, and your own vet is the one who can give a prognosis for your dog.

Benign or malignant: what a spleen mass can be

Lumps on the spleen are common in older dogs, and many are harmless.

• Benign: hematoma (a blood-filled swelling), nodular hyperplasia (an overgrowth of normal spleen tissue, very common with age), hemangioma and a few rarer types.
• Malignant: most often hemangiosarcoma, a cancer of blood vessel cells. Less often lymphoma, mast cell tumor, histiocytic sarcoma or another sarcoma.

The old rule of thumb is that about two-thirds of spleen masses are malignant and about two-thirds of those are hemangiosarcoma. That rule comes mostly from dogs brought in because the mass had already bled into the belly. For a mass found by chance, on a scan done for another reason in a dog with no bleeding, the published evidence points the other way: more benign than malignant. Benign masses can rupture and bleed too, so a bleed does not settle the question.

Dog spleen tumor life expectancy at a glance

Dog spleen benign tumor life expectancy

If the lab report says benign, removing the spleen has usually dealt with the problem. Most dogs live normally without a spleen, and life expectancy usually goes back to whatever it was for that dog's age and general health.

The risk sits in the operation and the days after it: blood loss, abnormal heart rhythms and, less often, blood clots. A small share of dogs do not survive that period, and the risk is higher in a dog that was bleeding and unstable going in. Vets also sometimes stay a little cautious in the first months, because a small hemangiosarcoma can be hidden inside a large blood clot and missed on the samples examined.

Malignant spleen tumor life expectancy

Hemangiosarcoma has almost always spread at a microscopic level by the time it is found, even when scans look clear. Removing the spleen stops the bleeding and buys time, and chemotherapy extends that time for some dogs. Most dogs feel well for much of it. The end usually comes as another bleed from a tumor that has grown elsewhere.

Without surgery after a bleed, some dogs rally as the body reabsorbs the blood, and seem almost normal for days or weeks. Then they bleed again, and the next bleed may be larger. Other malignant tumors behave differently, and an oncologist can give figures for the specific type. Our guide to cancer in senior dogs covers the general choices.

How long can a dog live with an enlarged spleen?

An enlarged spleen is a finding, not a diagnosis, so life expectancy follows the cause. Ask the vet whether there is a distinct lump on the spleen, which is what the rest of this article covers, or whether the whole spleen is evenly enlarged.

An evenly enlarged spleen can come from:

• Some sedative and anesthetic drugs, which enlarge it temporarily
• Infections, including some carried by ticks
• Immune diseases that destroy red blood cells or platelets
• Cancers that spread through the organ, such as lymphoma or mast cell disease
• A twisted spleen, an emergency seen mostly in large, deep-chested dogs

Some of these resolve with treatment and do not shorten life. Others are serious. Your vet may suggest blood tests, a scan or a needle sample to tell them apart.

How vets estimate the odds before surgery

• Abdominal ultrasound shows the mass, any free blood and the other organs. It cannot reliably tell a benign mass from a malignant one by appearance.
• Chest X-rays or a CT scan look for spread to the lungs.
• A heart scan may be offered, because hemangiosarcoma can also grow in the heart.
• Bloodwork and clotting tests check for anemia, low platelets and fitness for anesthesia.
• Needle samples are often not taken from blood-filled masses. They can cause bleeding and tend to yield mostly blood.

Findings that raise the suspicion of cancer include blood in the abdomen, anemia or low platelets, nodules in the liver or lungs, a mass in the heart, and breeds such as German shepherds, golden retrievers and Labradors. A mass found by chance, with no bleeding and a normal blood count, leans toward benign. None of these is certain either way.

The decision with an old dog: operating without a firm diagnosis

This is the hard part. You are usually asked to decide about major surgery before anyone knows what the mass is. The options are generally these:

1. Remove the spleen. It is the only way to get a diagnosis, and it stops or prevents bleeding. If the mass is benign, that usually ends the problem. If it is hemangiosarcoma, you have put an old dog through surgery for what is commonly a few more months, though often good ones.
2. Watch and rescan. Sometimes suggested by the vet for a small mass found by chance in a dog that is well. The risk is a bleed between scans.
3. Comfort care only. Often chosen when scans already show spread, or when heart or kidney disease makes anesthesia too risky. It means quiet living and a plan for what you will do if a bleed happens.
4. Euthanasia by the vet at the time of a major bleed. A kind and reasonable choice when the odds are poor or surgery is not possible for your dog or your family.

Questions that help: What did the chest and heart imaging show? How risky is anesthesia for my dog? What would recovery involve at this age? What would you expect if we do nothing? A quality-of-life scale for senior dogs gives you a baseline to compare against later, and how to know when it is time to say goodbye may help if you are weighing the last option.

What a bleed looks like

A bleeding spleen mass typically causes sudden weakness or collapse, pale gums, fast breathing and a swollen belly. A small bleed can pass in a day, leaving a dog who was flat and off food on Saturday looking normal on Monday. An unexplained bad day like that in an older dog is worth a vet visit even after the dog has recovered.

Call the vet today if

Go to your vet or an emergency clinic now if a dog with a known spleen mass or enlarged spleen, or any older dog:

• Collapses, cannot stand or is suddenly very weak
• Has pale, white or gray gums
• Has a belly that looks swollen or tight
• Is breathing fast or with effort while resting
• Seems cold, confused or unresponsive
• Has had spleen surgery in the last few days and becomes weak, stops eating or bleeds from the wound

Internal bleeding can be fatal within hours. Do not wait to see whether it passes, and do not give human painkillers such as ibuprofen, naproxen, aspirin or acetaminophen, which can seriously harm or kill dogs and can make bleeding worse.

This article is general educational information about spleen masses in dogs and is not veterinary advice. Survival figures are commonly reported ranges that vary widely, and a mass cannot be judged benign or malignant from an article or from a scan alone. Decisions about testing, surgery and care for your dog should be made with your veterinarian or a veterinary oncologist.