What Is an Enlarged Spleen in Dogs?

Hemangiosarcoma, a rapidly growing, invasive form of cancer that manifests in an enlarged spleen is a common problem in dogs.
What Is an Enlarged Spleen in Dogs?
Silvia Conde

Written and verified by the biologist Silvia Conde.

Last update: 18 November, 2023

An enlarged spleen is a worrying diagnosis, as this organ is very important for the defense of a dog’s organism — it’s part of their vertebrate immune system. This organ serves the same function in dogs as it does in humans. This is because it contains lymphocytes, the cells in charge of fighting invading microorganisms.

What’s the spleen for?

Firstly, the spleen is located in the left abdominal wall and is the main source of immune cells next to the lymph nodes, and it also has a blood-filtering action. Thus, it:

  • Prevents infections by producing lymphocytes that act against disease-causing microorganisms
  • Filters the blood and destroys old damaged cells
  • Finally, it stores red blood cells and platelets; these are involved in oxygenation and blood clotting
Illustration of a dog.

Enlarged spleen in dogs

Lymphoma and hemangiosarcoma tumors are the most common diseases that afflict the spleen. Also, hemangiosarcoma is the most frequent tumor in dogs. In addition, males have a greater predisposition for spleen problems, together with certain breeds, such as the German Shepherd, Golden Retriever, Labrador Retriever, and Boxer. Generally, it affects older dogs.


This is a malignant tumor that has a tendency to invade other body tissues. We don’t know the exact cause yet, and the prognosis isn’t favorable. So, the only treatment is mainly for extending the life of an animal as much as possible while maintaining their well-being.

Hemangiosarcoma can cause blood problems such as lack of coagulation. In addition, the symptoms of this disease aren’t too specific, but the following symptoms usually appear:

  • Swelling of the abdomen. The spleen becomes inflamed and enlarges (splenomegaly) by swelling the abdominal cavity.
  • Bigger lymph nodes. There are submandibular, prescapular, axillary, inguinal and popliteal nodes in a dog. You can actually feel them with your hands when they swell.
  • Anorexia or loss of appetite
  • Vomiting. The spleen takes up more space and can exert pressure on the stomach, causing the animal to vomit.
  • Lethargy
  • Fever
  • Weight loss
  • Hemorrhage. This is a hypovolemic shock and an emergency situation, so consult your vet immediately.
  • Anemia. A vet can detect this by doing a blood test.
  • Pale gums
  • Diarrhea
  • Dehydration
  • Cardiac disorders – an increase or decrease in normal heart rate

If the tumor continues to grow, it can break the spleen and lead to an acute collapse in the circulatory system, with difficulty breathing, and this will put the dog’s life at serious risk.

A sick dog.

Treatment of enlarged spleen in dogs

Proper diagnosis and treatment depend on the size and location of the tumor. Thus, the symptoms also pertain to the latter. So, you must rule out metastases to other organs through specific veterinary tests, such as x-rays, abdominal ultrasound, and mass analysis or biopsies.

Treatment requires surgery to remove the spleen and the proper medical term is splenectomy. However, this intervention doesn’t cure the disease, although it does help to slow down the process.

Vets use chemotherapy combined with surgery to remit cancer and extend a dog’s life expectancy. Chemotherapy in dogs – and cats – have fewer side effects than in people and can greatly increase their quality of life. The veterinarian prescribes the dosage and frequency of the chemotherapy treatment, but the owner alone decides how long they’d like to extend it.

Generally, chemotherapy after surgery greatly increases survival, so it’s worth continuing this treatment for as long as your veterinarian stipulates it.

Can a dog live without a spleen?

The answer is yes, but as long as it receives immuno-potentiating treatments. Also, you must take care of all aspects of the animal’s health, such as weight, activity, food, and visits to the veterinarian. However, if the problem is due to a malignant tumor, then the removal of the spleen won’t guarantee a cure.

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Canine Hemangiosarcoma – Symptoms and Treatments
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Canine hemangiosarcoma is a malignant tumor that occurs in the cells of the vascular endothelium and has a high mortality rate.

All cited sources were thoroughly reviewed by our team to ensure their quality, reliability, currency, and validity. The bibliography of this article was considered reliable and of academic or scientific accuracy.

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The contents of My Animals are written for informational purposes. They can't replace the diagnosis, advice, or treatment from a professional. In the case of any doubt, it's best to consult a trusted specialist.