Splenic Tumors

What Is The Spleen For?

• The spleen is an oblong organ (some would say it is tongue-shaped) seated just below the stomach on the left side of the body. Its consistency is similar to that of the liver.
• The spleen is involved in the immune system acting as a central processing plant for immune complexes acting like a huge lymph node.  In addition, the spleen is a site of red blood cell production.
• The spleen is also responsible for taking older red blood cells out of circulation, destroying them and recycling the iron and proteins in them.
• The spleen is responsible for removing various parasites from infected red blood cells.
• There are a lot of red blood cells working their way gradually through the spleen at any given time, effectively making the spleen a storage area for blood. If a dog has a severe hemorrhage and needs extra blood, the involuntary muscles of the spleen contract, squirting forth a fresh supply of blood. The spleen provides nature's blood transfusion, if you will. 
• The above functions are part of what is called the red pulp of the spleen.

Why Are Splenic Masses Bad?

Occasionally spleens grow masses. These are generally either benign tumors (hemangiomas) or malignant tumors (hemangiosarcomas grow from the red pulp, mast cell tumors and lymphosarcoma arise from the white pulp). In dogs, most splenic masses are either hemangiomas or hemangiosarcomas, while in cats they are usually either mast cell tumors or lymphosarcomas.

Since we are concerning ourselves here with dogs, we'll review the hemangioma and hemangiosarcoma. Both these tumors arise from the blood vessels of the red pulp and amount to a bunch of wildly proliferating abnormal blood vessels. Eventually the growth ruptures and the spleen bleeds. When a vascular organ like the spleen bleeds, a life-threatening blood loss can result.

• Usually the patient is suddenly weak.
• The patient may be obviously cold.
• If one looks at the color of the gums, the patient will be pale in color.
• If the bleed stops on its own, the patient will dramatically improve by the next day or even a few hours later.

Unfortunately, the splenic mass is certain to bleed again and if the spleen is not removed, eventually the patient will bleed to death.

If the splenic tumor is benign, removing the spleen is curative provided that the patient has not lost too much blood to survive the surgery. Ideally, a splenic mass is detected before it has ever bled and the spleen is removed when the mass is not actively bleeding. Of course, if the splenic mass is actively bleeding, removing the spleen becomes an emergency surgery; it is not appropriate to try to wait until the bleeding has stopped.

If the splenic tumor is a malignant hemangiosarcoma, the spleen can still be removed to control the bleeding, but the problem is that hemangiosarcoma is an aggressive cancer. With the removal of the spleen and primary tumor, the patient is probably spared death by bleeding to death only to eventually succumb to cancer.

Detecting Splenic Masses:

Another method of detecting a splenic tumor comes on the basic blood panel. An unexplained "responsive anemia" is discovered. A responsive anemia is one typical of bleeding (as opposed to an anemia of chronic disease where red blood cells simply are inadequately produced). An older large-breed dog with an unexplained bleed is highly suggestive of a splenic tumor. The next step would be radiographs to see if a mass is apparent, followed by chest radiographs for tumor spread as mentioned above. These findings on the blood panel are especially suggestive of a splenic mass if there has been a history of sudden weakness or collapse typical of a recent bleed. Splenic tumors tend to bleed chronically and slowly (and usually insignificantly) prior to a large bleed that produced obvious symptoms. These smaller bleeds are generally enough to alter the blood panel.

Ultimately, we rely on ultrasound examination of the belly to confirm or rule out a splenic mass.  With ultrasound, we can look directly into the spleen and look for abnormalities.  Unfortunately, ultrasound can only tell us that there is or isn't an abnormality, not what type of tumor is present.

Is it Benign or Malignant?

This is not always clear prior to surgery. If there is evidence of tumor spread on a chest radiograph, then one can be quite sure that the tumor is malignant. In this case it is likely too late to effect meaningful treatment.

If no evidence of tumor spread is present, the mass may be benign, or it may simply have produced tumor spread too small to see. In this case, one may simply proceed with splenectomy, understanding that tumor spread may be obvious in the abdomen once the belly has been opened.

If the spleen can be removed and minimal spread has occurred, then chemotherapy is a reasonable treatment option for maximizing quality life span.

Splenectomy (removal of the spleen)

• The spleen may begin bleeding at any time up until it is actually removed. If this occurs, blood transfusion is likely going to be needed (either with artificial blood or whole blood, depending on what is available). It is possible that multiple transfusions will be needed. A parameter called the packed cell volume (PCV) will be monitored to make sure the amount of circulating red blood cells does not fall dangerously low. If one is lucky, the spleen will not be bleeding at any time during surgery.
• It may not be known prior to surgery if the tumor is benign or malignant. There is a good chance this will become immediately obvious once the belly is opened. If the tumor is obviously malignant, will you want your dog euthanized at that point? Will you want the spleen removed so that you can consider chemotherapy? Will you want the incision simply closed and your dog awakened? These questions should be answered prior to surgery so that your veterinarian will know what to do should this situation arise. 
• The spleen and its large blood clots are likely to weigh 5 to 10 lbs in a large dog. The dog will appear substantially thinner after surgery. There will be a long incision to accommodate this very large organ and perhaps a bandage to control any leaking of blood from the incision.
• Most dogs go home a day or two after surgery. An iron supplement may be needed to help the body recover from any blood loss. Antibiotics will likely be prescribed as will some sort of analgesia (pain relief) for the recovery period.

examples of splenic tumors.

If You Choose Not to Remove the Spleen

Unfortunately, eventually the dog will have a bleed from which he cannot recover. If you think your dog is having a bleed at home, you can apply an ace bandage around the belly in a snug manner to essentially apply pressure to the bleed. This is surprisingly effective and may stave off the inevitable.

Chemotherapy is not an option if the primary splenic tumor is left behind; however, since a large percentage of splenic tumors are benign and splenectomy is curative in this situation, we recommend reconsidering surgery.