Spleen is present in the left-forward part of the abdomen near the stomach in dogs. The size of surrounding organs and the stomach affects the location of the spleen. Spleen is a dark, red colored organ which is relatively big in size and is the largest secondary lymphoid organ in the dog's body. The spleen is covered by a fibrous tissue, which is tough and hard. The pedicle is the place where the blood vessels enter and exit the spleen.

Functions of Spleen in Dogs
  • The spleen helps in the smooth functioning of the lymph and the immune system. The white pulp of the spleen consists of immune response cells which assist the immune system to fight infection.
  • Another spleen function in dogs is, it assists the blood systems in the filtration of blood. The marginal zone helps in filtration by separating the red and white pulp. The spleen has the capability of eliminating or removing the abnormal and old blood cells or particles present in the blood. It also has the ability of trapping the foreign particles and bacteria from the blood circulation, thus filtering the blood.
  • The red pulp helps in red blood cell formation and also in trapping and storing the immune proteins named as antigens. This function of the spleen is termed as hematopoiesis.
  • The spleen helps in the storage of blood, which is capable of contracting with the increase in the metabolic demands. While the spleen does not perform the function of contraction, it relaxes and serves the role of a blood reservoir and releases more red blood cells in the circulation.
Spleen Diseases in Dogs

Enlarged spleen in dogs can be a disease which can have an effect on the immune system. Spleen enlargement can also give rise to massive production of red blood cells and can also be a reason of anemia. Bleeding disorders, tumors and blood clots occur due to a spleen disease called hematoma. Hematoma means collection of blood. Twisting of spleen is also a commonly observed disease in large and deep chested dogs which can cause dog health problems. Twisting can cause stomach dilation and torsion. Benign tumors like hemangiomas can also affect the spleen. Malignant and cancerous tumors like canine hemangiosarcoma affects the middle aged and elder dogs. This is a severe disease and should be treated as soon as possible, as it can lead to the death of the dog. Apart from hemangiosarcoma, malignant tumors like lymphosarcoma, mast cell tumors (MCT) and multiple myeloma can also attack the dog's spleen.

In order to find the underlying problem of the spleen disease, exploratory surgery of the abdomen might be required. If, in spite of the surgery, the underlying problem still remains unknown, then spleen tissue will be required for diagnosis. But, most of the time, the spleen related dog illness can be identified by conducting abdominal ultrasound medical examination or a complete blood count test. Bone marrow aspiration, microscopic examination of the blood and abdominal radiographs may also be helpful for the same.