Enlarged Spleen in Dogs

Jamie Lovejoy, DVM
By Jamie Lovejoy, DVM on Mar. 21, 2024
A senior dog lays on grass.

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In This Article


What Is Splenomegaly in Dogs?

The spleen is an organ in a dog’s abdomen just behind the stomach that helps manage red and white blood cells for the body. The spleen keeps the body healthy by filtering the blood, storing cells that don’t need to circulate, and destroying cells that have reached their age limit.

A few conditions can cause abnormal growth and an enlarged spleen in dogs—referred to as splenomegaly. This is a relatively common abnormality and it can affect dogs of any age, size, or breed.

Splenomegaly can be very uncomfortable as the enlarged spleen presses on abdominal organs like the stomach and intestines. Abnormally large spleens are also at greater risk of being damaged, which can lead to extensive bleeding due to a large number of blood vessels in the organ. Furthermore, there is a possibility of the spleen rupturing, exacerbating the condition and necessitating immediate medical attention.

The prognosis for splenomegaly in dogs depends heavily on the cause of the enlargement and whether the spleen has ruptured. Dogs with a moderately enlarged spleen and no other symptoms may be stable but should be evaluated promptly by a veterinarian.

A splenic rupture is a medical emergency and should be evaluated and treated immediately.

Symptoms of Splenomegaly in Dogs

Symptoms of an enlarged spleen in dogs include:

Causes of Splenomegaly in Dogs

When considering the potential causes of an enlarged spleen in dogs, various factors may contribute, including:

How Veterinarians Diagnose Splenomegaly in Dogs

Vets will likely suspect an enlarged spleen in dogs based on a physical exam and medical history.

In many dogs, an abnormal spleen can be felt in the abdomen. This may be difficult in very large or overweight dogs, and your vet will probably recommend imaging of the abdomen to confirm the diagnosis.

Splenomegaly in dogs should be visible on abdominal radiographs, although abdominal ultrasound can give valuable information, especially in cases where cancer is suspected. Chest X-rays may also be taken to look for evidence of cancer.

A complete blood count (CBC), blood chemistry, and urine testing can help evaluate potential causes of spleen enlargement, such as liver inflammation or leukemia (blood cancer). They can also assess for serious consequences of splenomegaly, like an abdominal bleed (hemoabdomen). A blood screen for heartworm and tick-borne diseases may help rule out infectious causes.

If a tumor is suspected or if the cause of the enlarged spleen is still unknown, a biopsy is usually required. An aspirate of the spleen can be performed with an ultrasound-guided needle, though in most cases, your veterinarian will recommend removing the entire spleen (splenectomy) to prevent complications. While this organ serves an important function, the body has other organs that can compensate, and dogs can live happy, healthy lives without their spleen.

Treatment of Splenomegaly in Dogs

When the spleen is enlarged due to problems elsewhere in the body, treatment is directed at the primary issue rather than the spleen itself.

Viral and bacterial infections can usually be cured with medications. Rarer causes of enlarged spleen in dogs—such as inflammatory bowel disease (IBD) or other immune disorders—may require long-term management with prescription diets and immunosuppressants to prevent recurrence.

Non-cancerous causes of splenomegaly, like trauma and benign tumors, are commonly treated by splenectomy. Sick dogs may require hospitalization and even blood transfusions to stabilize them for surgery, but once they recover, these pups typically have a good long-term prognosis.

Unfortunately, malignant cancers that affect the spleen, such as hemangiosarcoma and lymphoma, generally result in a poor prognosis, even with aggressive therapy.

Splenectomy is usually indicated with hemangiosarcoma to improve comfort for as long as possible. If there isn’t significant bleeding, some pet parents may opt for palliative treatments such as anti-nausea medications, pain medications, and herbs to help prevent bleeding (e.g., Yunnan Baiyao).

Chemotherapy can be used with or without surgery with many splenic cancers to give dogs more time, although how much will depend on the type of cancer.

Recovery and Management of Splenomegaly in Dogs

Systemic illnesses that cause enlarged spleen in dogs may take days to weeks to resolve, depending on the underlying cause. The spleen should return to its normal size once the primary condition has been treated, and affected dogs typically feel much better.

Dogs who undergo splenectomy typically need two to three weeks to recover once they have left the hospital. If a blood transfusion was needed, follow-up blood tests are recommended, but these dogs can usually return to routine veterinary care once they have healed.

If a malignant cancer is diagnosed in the spleen, surgical recovery is usually similar but long- term survival is not expected. The most common cancer found in a dog’s spleen is hemangiosarcoma. Even with surgery and chemotherapy, recurrence of this disease is common, and most dogs live less than a year after diagnosis.

Frequent follow-up blood tests and imaging can help pet parents of dogs with splenic cancer monitor for complications.

Prevention of Splenomegaly in Dogs

Routine vaccinations and parasite prevention can help avoid infectious causes of enlarged spleen in dogs.

Unfortunately, cancers and even benign tumors of the spleen cannot be prevented. Routine wellness exams and blood work can help you and your veterinarian discover problems early.

Weight loss, behavior changes, and appetite changes should be evaluated promptly by your vet.

Splenomegaly in Dogs FAQs

Can an enlarged spleen go back to normal size?

Enlarged spleens that are reacting to illness in a dog’s body can quickly return to normal size with appropriate treatment. An enlarged spleen in dogs that is caused by tumors or trauma will not resolve and may require surgery.

Jamie Lovejoy, DVM


Jamie Lovejoy, DVM


Dr. Jamie Lovejoy graduated from Tufts Cummings School of Veterinary Medicine in 2012 after an undergraduate degree in Marine Biology. ...

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