Dog: Splenomegaly

General information

Other common/scientific names: enlarged spleen

The spleen is an oblong organ which is attached to the stomach. It is highly vascularized meaning there are several blood vessels which carry blood to and from the spleen. While a dog can live perfectly well without a spleen, it does perform many functions involving the circulatory and immune systems. The spleen stores blood which can be used by the body in times of hemorrhage or blood loss. It can also produce red blood cells when needed. The spleen filters the blood by removing injured and abnormal blood cells. It also recycles iron from destroyed red blood cells. The spleen is part of the immune system by producing antibodies and white blood cells which help to fight infections.


An enlarged spleen can be caused by:

Abb. GGKPQ1YO: Tumor of the spleen.
This is a photograph of an enlarged spleen caused by a tumor. This spleen has been surgically removed.

Cardinal symptom

Lack of energy


Clinical signs of an enlarged spleen will depend on the cause but include lack of energy, weakness, abdominal pain, distention of the abdomen or bloated appearance, fever, weight loss, lack of appetite, pale gum color, diarrhea and vomiting. In severe cases, the enlarged spleen can press on the chest and lungs causing shortness of breath. Dogs may have an enlarged spleen for months and never show clinical signs until the spleen ruptures (splenic rupture). Within hours, they can be found collapsed and in shock from internal bleeding.


Some dogs with splenomegaly show obvious abdominal distention meaning their abdomen bulges with the enlarged spleen. This can be palpated (felt) on examination. Radiographs and ultrasonography are used to confirm an enlarged spleen. A complete blood count (CBC), serum biochemistry and electrolyte panel and urinalysis are performed to determine the cause of splenomegaly. If a tumor is diagnosed and malignancy is suspected, radiographs and ultrasonography can be used to help determine if the cancer has spread to other organs.


If a ruptured spleen and internal bleeding is suspected, emergency treatment will be needed. A blood transfusion may be necessary if the dog has lost a large amount of blood from the rupture. If the enlarged spleen is caused by a tumor and the cancer has not spread, then the spleen can be surgically removed (splenectomy). It may not always be known prior to surgery whether the tumor is benign or malignant. During the surgical procedure, a complete exploratory of the abdomen should be performed to check for spread of the cancer. A splenectomy may also be the treatment of choice for splenic torsion (twisted).

An enlarged spleen due to infection, congestion or hyperplasia can be treated with appropriate medications aimed at treating the primary cause.


The prognosis of an enlarged spleen will depend on the cause. In cases of benign tumors, the prognosis is good and surgery is curative. Other conditions such as malignant tumors, infections, torsion and autoimmune disease may carry a more guarded prognosis. A ruptured spleen can be fatal if not diagnosed and treated promptly.

Update version: 4/24/2014, © Copyright by
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