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SPLENIC MASSES IN DOGS
HEMANGIOSARCOMA, HEMATOMA AND SPLENIC TORSION
Hemangiosarcoma (HSA):
Overview
HSA is a common tumor of the spleen usually seen in older dogs (8-10 years of age). Any large breed dog appears to be at an increased risk especially German Shepherds, Golden Retrievers, Labradors and Poodles.
Clinical Signs
Signs can be subtle and include weakness or may be more obvious eg. collapse and sudden death if the mass ruptures and bleeds internally. Mucous membranes (such as the gums) may be pale and heart and respiratory rates can be increased. Abdominal distension, weight loss, inappetance, cardiac arrhythmias (abnormal heart rhythm) and associated syncope (fainting) or weakness can also occur. If the tumor spreads to the brain, seizures may result. Tumor spread (metastasis) is present in more than 80% of dogs at presentation. Spread to other abdominal organs, lungs, bones and brain among other sites is common.
Diagnosis
Your veterinarian may need to run several tests to obtain a presumptive diagnosis and to prepare for surgery. This may include blood tests, urinalysis, a clotting profile, examination of fluid obtained from the abdomen (called abdominocentesis) as well as chest and abdominal radiographs. Abdominal ultrasound is another useful modality to identify masses in the abdomen as well as free fluid or blood. Echocardiography (ultrasound of the heart) is often recommended as up to 15% of dogs may have tumor spread to the right atrium on initial presentation. An ECG to look for arrhythmias may also be required especially after surgery. Up to 24% of dogs with splenic HSA have arrhythmias and these may not be noted until after surgery. While this may require treatment, most resolve within 24-48 hours. A definitive diagnosis requires examination of the mass by a pathologist.
Treatment
Surgery is the primary method of treatment for dogs with HSA. This involves removal of the spleen (splenectomy). Removal of the spleen is preferred to a biopsy as it serves as both a diagnostic and therapeutic procedure. Patients are stabilized prior to surgery. This may require fluid therapy or a blood transfusion and intensive care monitoring. Complications that may be associated with surgery include hemorrhage (ongoing bleeding), cardiac arrhythmias and pancreatitis (often manifest by vomiting). The final diagnosis relies on histopathology of affected tissue – examination of a section of tissue under a microscope. Splenic hematomas and hemangiomas as well as other benign disease can have a similar clinical presentation and must be differentiated from hemangiosarcoma. Up to 2/3 of dogs with splenic masses have a malignant tumor (2/3 of these are HSA). The remaining patients have benign masses that are effectively treated with splenectomy.
Figure 1. A splenic mass at the time of surgery. The spleen has been removed from the abdomen and the surgeon's hand is on the mass. The normal portion of the spleen is to the right of the large mass.
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Figure 2. A spleen with a large splenic mass following complete removal of the spleen at surgery.
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Prognosis
Unfortunately, mean survival times with surgery alone range from 19-86 days. One year survival is less than 10%. Ultimately dogs die of metastatic disease. Chemotherapy (usually with doxorubicin based protocols) may increase survival times up to 141-179 days but must weighed against the risk of side effects (gastrointestinal upset, bone marrow suppression). Immunomodulators (such as a bacterial vaccine and LE-MTP-PE) and angiogenesis modifiers are currently under investigation and may prove useful in the future. Continuous low-dose chemotherapy also shows promise. There is no known prevention for this cancer.
Hematoma and Nodular Hyperplasia:
These are the most common non-neoplastic lesions found in the spleen and account for 20-41% of all splenic lesions. They are benign nodules/masses of clotted blood. Surgical removal is curative.
Splenic Torsion:
Overview
This occurs when the spleen rotates/twists thus preventing blood drainage and subsequent enlargement of the spleen. It occurs in large and giant breed dogs (eg. Great Danes, German Shepherds) with deep chested conformation. It may occur on its own (rare) or in combination with GDV (gastric dilatation-volvulus). Rolling, retching and exercise may increase the spleens ability to move along with stretching of the ligaments that normally stabilize the spleen, resulting in twisting of the spleen.
Clincal signs
This can be an acute condition manifested with pain and collapse or it may be more chronic and associated with non-specific signs such as intermittent abdominal pain, vomiting, inappetance, abdominal distension, weight loss and excessive drinking and urination.
Diagnosis
Abdominal radiographs and ultrasound are extremely useful in confirming the diagnosis. Other tests that may be required include blood and urine analysis. In certain cases, an exploratory surgery may be required to obtain the diagnosis. Find an ACVS Veterinary Surgeon
Treatment
Patients are stabilized prior to surgery with fluid therapy and blood if necessary.
Surgical removal of the spleen is then performed. Complications from surgery may include cardiac arrhythmias, ongoing hemorrhage, pancreatitis (associated with vomiting) and infection although the overall prognosis is good.
—Kevin Isakow, BVsc, MVSc
Diplomate ACVS
Posted 8/15/2008
Photos provided courtesy of Elizabeth Hardie, DVM, PhD, Diplomate ACVS
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