Spleen Cancer in Dogs

Most spleen tumors are a sign of cancer in dogs. The spleen is a vital immune organ that stores blood, destroys old blood cells and replenishes the body's blood supply in an emergency. Dogs without spleens are more vulnerable to infection.

Your Dog's Spleen and Its Function

Your dog's spleen is located in his abdomen and is somewhat elongated in shape, like a tongue. The spleen's location may vary somewhat, depending on the size and shape of other nearby organs, which may apply pressure to the spleen.

The canine spleen is large and dark red in color; it's supplied by a number of blood vessels. The spleen is longer than it is wide and may be somewhat constricted in the middle. A capsule of fibrous tissue surrounds and protects the canine spleen. The size of the spleen can change, as sometimes it becomes engorged with blood.

Blood vessels enter and exit the spleen at one of its ends; this end is known as the pedicle. Inside the spleen are found three different structures:

  • Red pulp, which is where red blood cells are formed and stored, and where antigens are housed.
  • White pulp, where white blood cells are formed and stored.
  • A marginal zone between the red and white pulp, to separate the two pulps and filter the blood that passes between them.

Some of the functions of the canine spleen include:

  • Creation and storage of white blood cells
  • Creation and storage of red blood cells and platelets
  • Phagocytosis, a process by which the spleen removes foreign proteins, old blood cells and bacteria from the blood

Your dog's spleen is responsible for creating a large number of his red blood cells. The spleen plays a key role in immune function.

Spleen Tumors

Spleen tumors can be cancerous or benign (not cancerous), but most are cancerous. Therefore, a splenic tumor is cause to suspect cancer in dogs. Tumors in the red pulp are known as hemagiosarcoma. These tumors are rare and occur in the blood vessels that line blood-filled spaces. A second type of spleen tumor is located in the white pulp and may be the result of mast cell cancer or lymphosarcoma in dogs.

Treating Spleen Cancer and Non-Cancerous Spleen Tumors

Symptoms of spleen tumors can be difficult to pin down, as they're similar to the symptoms of many other serious diseases. Symptoms of spleen cancer in dogs include:

In some cases, the spleen tumor may be big enough to feel or see. The most definitive symptom of spleen cancer in dogs is a change in urine color to dark brown.

Cancerous tumors of the spleen require complete removal of the spleen. Your dog will be at increased risk for infection following such a surgery.

Even non-cancerous spleen tumors can be dangerous to your dog's health, because they can rupture and cause rapid death from internal bleeding. However, surgery to remove benign spleen tumors is usually safer and more successful than spleen cancer surgery in dogs.