What is Spleen Cancer in Dogs?
The spleen is oblong shaped and located in the abdomen, below the stomach. While the spleen does play a role in keeping animals healthy, it is not a vital organ and can be removed with few long-lasting effects.
Splenic tumors are very common in dogs, especially as they grow older. Because the spleen stores and produces red blood cells, even benign tumors may be at risk of rupture and bleeding, causing acute illness.
Veterinarians class tumors as:
Primary (originated in the spleen) or secondary (spread from another tumor somewhere else)
Focal (located in one area) or diffuse (spread throughout the entire organ)
Hemangioma and hemangiosarcoma are two of the most common primary tumors found in spleens. Hemangiomas are benign, while hemangiosarcomas are malignant. The prognosis for
Any dog can develop tumors in their spleen, but older, larger breed dogs are at higher risk. Breeds most at risk include:
Bernese Mountain dog
Benign Spleen Tumors
Benign spleen tumors are non-cancerous but are easy to confuse with malignant tumors. When veterinarians find any tumor on the spleen, they may recommend additional tests to rule out more sinister
Malignant Spleen Tumors
While the prognosis for benign tumors is typically good if discovered early, the same is not true for malignant tumors. The outcome for malignant tumors varies based on how aggressive the cancer is. Common malignant tumors in the spleen
Lymphoma or lymphosarcoma: This is a highly variable type of round cell tumor that typically involves the lymph nodes as well as other organs. Lymphoma is typically aggressive with a poor prognosis.
Leukemia: Leukemia is typically a cancer of cells within the bone marrow, but can originate in or infiltrate the spleen. Canine leukemia is rare, but typically carries a poor prognosis with splenic involvement.
Other round cell tumors include mast cell tumors, plasma cell tumors, and multiple myeloma. Prognosis varies with severity and metastasis but is generally guarded.
Histiocytic sarcoma: This type of sarcoma is very common in Bernese Mountain Dogs, as well as other breeds. Prognosis is very poor to grave in most cases of histiocytic sarcoma.
As with all other types of splenic neoplasia, the type, aggressiveness, and location determine prognosis. There are many other less common types of malignant splenic tumors, mostly all carrying a similar poor prognosis, including:
Secondary tumors are also common in the spleen. These are caused by cancerous spread from other sites in the body. Because the spleen is very vascular, meaning it has a rich blood supply, it’s a common site for secondary tumors.
Causes of Spleen Cancer in Dogs
The cause of most splenic tumors is unknown. German Shepherds, Labrador Retrievers, Golden Retrievers, Boxers, and Standard Poodles may have a higher risk of splenic tumors in general. Bernese Mountain Dogs and Flat-Coated Retrievers may have a genetic link to histiocytic sarcoma. Splenic cancer can occur in all ages of dogs, but veterinarians most often diagnose in older dogs.
How Veterinarians Diagnose Spleen Cancer in Dogs
Blood chemistry and complete blood count (CBC)
Veterinarians will often recommend bloodwork as a first step to determine overall health after diagnosing a splenic tumor. A bleeding or ruptured tumor will often lead to anemia (low red blood cell count) and low platelets, which can be detected by a complete blood count. The blood chemistry panel may show issues common to many conditions, such as dehydration.
Because low platelets and other factors necessary for clotting are common signs in some types of splenic tumors, coagulation tests will be done to determine if a dog is at risk for severe bleeding issues. This type of test (
Radiographs, or x-rays, are useful to determine the overall size, shape, and placement of the spleen in reference to other abdominal organs. Veterinarians may note obvious masses in the spleen, or it may be generally enlarged and abnormally shaped. Veterinarians will also want to take x-rays of the lungs to look for cancerous spread.
Ultrasonography allows more detailed analysis of the internal structure, location, and size of the spleen and other abdominal organs. Veterinarians will also use ultrasound as a guide when they obtain biopsies, which is one way to get a definitive diagnosis. Veterinary radiologists evaluate the entire abdominal cavity for other tumors, abnormalities, and fluid.
Fluid analysis and cytology
Dogs with a ruptured
Splenic biopsy can be performed under ultrasound guidance with a large needle to collect a sample of spleen cells, as well as during surgical removal of the spleen.
Treatment of Spleen Cancer in Dogs
Regardless of whether a splenic tumor is malignant, removal of the spleen, called a splenectomy, is most often recommended as treatment for primary splenic tumors because even benign tumors can rupture and cause life-threatening illness.
The surgery is relatively simple, and may not require a veterinary specialist to perform, as many general practitioners are comfortable. The spleen is not a vital organ, and therefore vets remove the entire spleen, not just the tumor.
Before surgery, a complete work-up should be performed to look at overall health and cancer spread, called cancer staging. This may include bloodwork, x-rays of the chest and ultrasound of the abdomen. Based on the findings of these tests, vets will determine if a patient is a good surgical candidate for splenectomy.
In the cases of advanced disease, cancerous spread, or poor surgical candidacy, surgery may not be recommended. However, there are cases of malignant tumors that may still benefit from a splenectomy.
Veterinary oncologists typically recommend chemotherapy after removal of splenic tumors, based on the specific tumor type. In some cases, depending on the type of tumor, chemotherapy is not necessary.
Medications are typically not a primary recommendation for dogs with splenic tumors. However, if a patient is not a candidate for surgery, medication may improve their quality of life. Dogs who do not have the spleen removed are still at risk of splenic rupture, and many vets utilize the Chinese herbal supplement Yunnan Baiyao to help control bleeding.
Other medications, such as steroids, are prescribed in some types of cancer. Unfortunately, these medications do not cure anything and only make the dog’s quality of life better for a short period of time.
Prognosis of Spleen Cancer in Dogs
Prognosis of splenic cancer varies based on diagnosis. When caught early, benign tumors, most notably hematomas and other vascular tumors, may only require a splenectomy to prevent a rupture and hemorrhage. If the tumor was found coincidentally, and the pet is not actively sick, the prognosis may be excellent with full life expectancy.
Patients who have concurrent illnesses, or if benign tumors chronically or acutely rupture, can also have clotting and anemia issues and may have a more guarded prognosis.
Malignant tumors carry a more guarded to grave prognosis. Many dogs are not stable enough to undergo anesthesia due to the changes in blood and coagulation factors. Because of this, many dogs undergoing an emergency splenectomy pass away or are euthanized during surgery.
Survival times after a splenectomy range from less than month to up to three months for dogs with splenic hemangiosarcoma (one of the
Dogs who receive no treatment of malignant, bleeding splenic tumors have an extremely dire prognosis. Tumors can bleed slowly, with the dog showing varying signs of illness and weakness. Tumors can also rupture acutely and traumatically. These dogs are critically sick, weak, and can die from loss of blood. These patients should be immediately evaluated by a veterinarian to determine if surgery is still an option or if humane euthanasia is the best choice.
Recovery and Management of Spleen Cancer in Dogs
All splenic tumors should be biopsied for a definitive diagnosis. Surgery may be curative for benign tumors with no other illnesses or complications.
For those patients with more advanced disease, rechecks with surgeons and oncologists may be scheduled initially at 2 weeks, and then every 1-3 months depending on the plan going forward. The veterinarians will likely check bloodwork parameters, x-rays, and ultrasounds at these visits to monitor disease progression and quality of life.
Based on the severity of the disease, some complications may require more intensive care and monitoring such as:
Continued hemorrhage and loss of blood
Blood transfusions from coagulation issues
Blood transfusions from blood loss
Low blood pressure secondary to blood loss
Spleen Cancer in Dogs FAQs
How long do dogs live with spleen cancer?
Depending on the type and severity, dogs with splenic cancer may live for weeks to months.
What happens to a dog with spleen cancer?
Dogs with splenic cancer are at high risk of loss of blood from a bleeding tumor, especially those with hemangiosarcoma.
Are spleen tumors in dogs painful?
Dogs may be in pain, especially if the tumor ruptures. Occasionally they are asymptomatic.