THE SPLEEN - ENLARGEMENT AND TUMORS IN DOGS
The spleen is a sponge-like organ located approximately in the middle of the abdomen. It is important in red blood cell production and maintenance, immune system functions, and blood storage. Despite these functions it can be surgically removed (splenectomy) with little or no effect on a patient's quality or quantity of life. The spleen is a common site for tumors to occur in dogs.
TYPES OF SPLENIC TUMORS AND REASONS FOR ENLARGEMENT OF THE SPLEEN
One-half to two-thirds of splenic tumors are malignant; one-half to two-thirds of these malignant tumors are a malignancy called hemangiosarcoma. Many other types of tumors, both benign and malignant, can occur in the spleen.
Non-cancerous reasons for splenic tumors or splenic enlargement include various infections, immune-mediated diseases, and obstructions to blood flow through or out of the spleen.
SIGNS AND COMPLICATIONS OF SPLENIC TUMORS
We have found some splenic tumors as part of routine physical exams; the owners had noticed no signs.
Most signs are due to either the size of the tumor or bleeding from the tumor. Tumors of the spleen can reach a great size. Large tumors can press on the stomach and cause a decreased appetite and, less commonly, press on the urinary bladder and cause incontinence. Some owners have noticed enlargement of their dog's abdomen.
Splenic tumors are also prone to rupture and subsequent bleeding into the abdomen. Depending on the severity of the bleeding signs range from nothing to a brief period of weakness, to fainting and even sudden death.
We can often diagnose the presence of an enlarged spleen by palpating the abdomen on a physical exam. If this is found or suspected then we generally recommend abdominal xrays and abdominal ultrasound exam to confirm the splenic tumor.
A complete pre-surgical diagnostic test profile to determine the extent and effects of the splenic enlargement and to check for evidence of potential metastasis (spread to other organs) includes:
- cbc, blood profile
- chest and abdominal x-rays
- abdominal ultrasound exam
- echocardiogram (ultrasound of the heart)
We have infrequently encountered patients who had no evidence of tumor complications with this careful and thorough diagnostic screen, but who had evidence of metastasis on the surgical exploratory that happens at the time of splenectomy.
Large tissue samples are needed for biopsies of the spleen; smaller samples that are sufficient for diagnosis of many other types of tumors are not reliably accurate for determining what type of tumor is present in a spleen. In other words, removing the entire spleen is necessary for obtaining a diagnostic biopsy sample. (Accurate diagnosis can still be challenging; even with a large sample biopsy results can be wrong. We have encountered a few patients who had biopsy results of a benign tumor based on a substantial sample who ultimately developed metastatic disease because their original tumors were actually malignant.)
Surgical removal of the spleen is the treatment of choice for splenic tumors.
When the subsequent diagnosis is hemangiosarcoma, it is our opinion that there is not currently any worthwhile follow-up with chemotherapy, but it is an option that could be pursued. When the diagnosis is some other type of malignant tumor chemotherapy might be a more reasonable post-surgical treatment option.
SOME SURGICAL DETAILS In our experience complications during and immediately before and after surgery are rare. Our patients remain hospitalized overnight for one night after surgery. Splenectomy is a major surgery; most of our patients are bright and alert and eating well when they go home from surgery but require a week to two to get back to being their "usual selves".
We recommend that owners have a very difficult discussion before bringing their pet in for surgery: what will you want to do if we call during surgery to say that we have discovered evidence of metastasis. The options are, in no particular order, are:
- proceed with removal of the spleen
- close the patient's incision and recover the patient from anesthesia without removing the spleen
- euthanize the patient while it is anesthetized on the surgery table
There is no "right' answer that applies to all patients. We will help you as much as we possibly can to make the choice that is right for you and your pet.
Patients with benign tumors of the spleen typically live normal lives, and suffer no ill effects from having had their spleen removed.
Patients with hemangiosarcoma have an average survival time of 3 months post surgery, with a range of a few weeks to a little more than a year. Dogs with other splenic malignancies have roughly similar survival times.