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Spleen Cancer in Dogs

What is Spleen Cancer in Dogs?

Spleen cancer in dogs encompasses various types of tumors that affect the spleen, a crucial organ involved in the immune system and blood cell production. The spleen, positioned below the stomach in the abdominal area, aids in fighting infections, generating white blood cells, and managing red blood cells and platelets.

Tumors in the spleen are quite common among older dogs, with the potential risk of rupture and bleeding even in benign cases due to the organ’s role in blood storage and production. Veterinary classification distinguishes between benign and malignant tumors, as well as primary and secondary tumors (originating in the spleen or spreading from elsewhere) and focal or diffuse growths.

Hemangioma and hemangiosarcoma represent prevalent primary tumors affecting the spleen. Hemangiomas are typically non-cancerous, while hemangiosarcomas are malignant. Prognosis varies based on tumor type, with benign tumors generally offering a better outcome, especially when treated promptly.

Certain dog breeds, particularly older and larger breeds such as German Shepherds, Golden Retrievers, Labrador Retrievers, Boxers, Standard Poodles, Bernese Mountain Dogs, and Flat-Coated Retrievers, face a heightened risk of developing spleen tumors.

Benign Spleen Tumors

Benign spleen tumors, while non-cancerous, often resemble malignant tumors, leading veterinarians to conduct further tests to exclude more serious conditions when they detect any spleen tumor. Unlike malignant tumors, benign tumors do not metastasize or spread to other body parts. Although they can be removed, many benign tumors carry a favorable prognosis, especially if diagnosed early.

Malignant Spleen Tumors

In contrast to the typically favorable prognosis associated with benign tumors when detected early, malignant spleen tumors present a different scenario. The prognosis for malignant tumors varies depending on their aggressiveness. Among the common malignant tumors affecting the spleen are:

  • Lymphoma or lymphosarcoma: This aggressive round cell tumor usually affects lymph nodes and other organs, leading to a generally poor prognosis.
  • Leukemia: While rare in dogs, leukemia can originate in or infiltrate the spleen, often resulting in a poor prognosis, especially when the spleen is involved.
  • Other round cell tumors such as mast cell tumors, plasma cell tumors, and multiple myeloma also pose challenges in prognosis, which depends on the severity and extent of metastasis but is generally cautious.
  • Histiocytic sarcoma: This sarcoma, prevalent in Bernese Mountain Dogs and other breeds, typically carries a very poor to grave prognosis.

The prognosis for malignant spleen tumors, including less common types like leiomyosarcoma, melanoma, and carcinoma, remains grim due to their typically aggressive nature. Secondary tumors, originating from cancerous spread from other parts of the body, are also prevalent in the spleen due to its highly vascular nature, posing additional challenges in prognosis and treatment.


Symptoms of spleen cancer in dogs often manifest subtly or may not be noticeable at all, frequently discovered incidentally during diagnostic evaluations for other health concerns. The primary concern with spleen tumors is the risk of rupture. Given the spleen’s abundance of blood vessels, even benign tumors carry the potential to rupture, resulting in either gradual or rapid bleeding. Gradual bleeding may exhibit milder symptoms, whereas sudden bleeding can lead to acute, severe, and life-threatening blood loss into the abdominal cavity.

Common indications of a spleen tumor or bleeding comprise:

  • Lethargy
  • Reduced appetite
  • Weakness
  • Collapsing episodes
  • Pale gums
  • Abdominal distension (e.g., bloating or swelling)
  • Cold limbs
  • Irregular heart rhythms


The precise cause of most splenic tumors remains unidentified. However, breeds such as German Shepherds, Labrador Retrievers, Golden Retrievers, Boxers, and Standard Poodles appear to have an elevated susceptibility to splenic tumors overall. Additionally, Bernese Mountain Dogs and Flat-Coated Retrievers may have a genetic predisposition to histiocytic sarcoma. While splenic cancer can affect dogs of all ages, veterinarians commonly diagnose it in older dogs.


Veterinarians can suspect the presence of a bleeding splenic tumor in dogs through clinical signs and physical examination alone. Tumors of significant size may be detectable through palpation of the abdominal walls, and the presence of a fluid wave in the abdomen due to bleeding is often observed as well.

Blood chemistry and complete blood count (CBC)

As an initial step after diagnosing a splenic tumor, veterinarians frequently advise bloodwork to assess overall health. Anemia (a low red blood cell count) and reduced platelet levels, indicative of bleeding or a ruptured tumor, can be identified through a complete blood count. Common issues like dehydration may also be revealed by the blood chemistry panel, typical of many conditions.

Coagulation Tests

Due to the prevalence of low platelet levels and other clotting factors associated with certain types of splenic tumors, veterinarians conduct coagulation tests to assess the risk of severe bleeding in dogs. These tests, including prothrombin and partial thromboplastin times, determine the clotting time of blood. Anomalous results may suggest advanced disease and heightened susceptibility to further bleeding. Coagulation tests are administered when bleeding is suspected, aiding in treatment decisions such as blood product transfusions, which can enhance survival prospects during surgery.


Radiographs, commonly known as x-rays, serve as valuable tools to assess the size, shape, and positioning of the spleen relative to other abdominal organs. Veterinarians may identify evident masses within the spleen or observe its general enlargement and irregular shape. Additionally, veterinarians will conduct x-rays of the lungs to detect potential cancerous spread.


Ultrasonography provides a more in-depth examination of the internal structure, position, and dimensions of the spleen and other abdominal organs. Veterinarians utilize ultrasound as a navigational tool during biopsy procedures, offering a means to achieve a conclusive diagnosis. Veterinary radiologists meticulously assess the entire abdominal cavity for additional tumors, irregularities, and the presence of fluid.

Fluid analysis and cytology

Abnormal fluid buildup in the abdomen is a common occurrence in dogs with a ruptured splenic tumor. Usually consisting of blood, veterinarians can readily extract a sample by inserting a needle into the abdominal fluid. By examining this fluid under a microscope, veterinarians can search for cancerous cells. While this approach may be particularly useful in diagnosing lymphoma and mast cell tumors, its accuracy isn’t guaranteed in all cases.


A splenic biopsy can be conducted with the assistance of ultrasound, utilizing a large needle to gather a sample of spleen cells. Alternatively, biopsy can be performed during the surgical extraction of the spleen.

Treatment of Spleen Cancer in Dogs


Regardless of whether a splenic tumor is malignant, the primary treatment recommendation is often the removal of the spleen, known as a splenectomy. This is because even benign tumors can rupture, leading to life-threatening complications.

The procedure is typically straightforward and may not necessitate the expertise of a veterinary specialist, as many general practitioners are proficient in performing it. Since the spleen is not essential for survival, veterinarians opt to remove the entire organ rather than just the tumor.

Before surgery, a comprehensive evaluation should be conducted to assess overall health and determine the extent of cancer spread, referred to as cancer staging. This evaluation may involve blood tests, chest x-rays, and abdominal ultrasound. Based on the results of these assessments, veterinarians will decide whether a patient is suitable for splenectomy surgery.

In instances of advanced disease, widespread cancer, or poor surgical candidacy, surgery may not be advisable. Nevertheless, there are situations involving malignant tumors where a splenectomy can still offer benefits.


Following the removal of splenic tumors, veterinary oncologists often advise chemotherapy based on the tumor’s specific type. However, in certain instances, depending on the tumor type, chemotherapy may not be deemed necessary.


As a primary recommendation, medications are typically not favored for dogs with splenic tumors. However, if a patient is not eligible for surgery, medication might enhance their quality of life. Dogs who retain their spleen remain susceptible to splenic rupture, prompting many veterinarians to administer the Chinese herbal supplement Yunnan Baiyao to help manage bleeding.

In certain types of cancer, steroids and other medications may be prescribed. Unfortunately, these medications do not offer a cure and only provide temporary improvements in the dog’s quality of life.

Prognosis of Spleen Cancer in Dogs

The prognosis of splenic cancer varies depending on the diagnosis. In cases where benign tumors like hematomas and other vascular tumors are detected early, a splenectomy might suffice to prevent rupture and hemorrhage. If the tumor is incidentally found and the pet is otherwise healthy, the prognosis can be excellent, with a full life expectancy.

Patients with concurrent illnesses or those experiencing chronic or acute rupture of benign tumors may face clotting and anemia issues, leading to a more guarded prognosis.

Malignant tumors generally carry a guarded to grave prognosis. Many dogs may not be stable enough for anesthesia due to blood and coagulation factor changes. Consequently, some dogs undergoing emergency splenectomy may not survive the surgery or may be euthanized during the procedure.

Survival times following splenectomy range from less than a month to up to three months for dogs with splenic hemangiosarcoma, one of the most severe malignant tumors. Dogs treated with splenectomy and chemotherapy may experience longer survival times depending on their specific case. However, individual diagnosis, stage, and metastatic rates can complicate the prognosis.

Dogs with untreated malignant, bleeding splenic tumors face an extremely dire prognosis. These tumors can bleed slowly, leading to varying signs of illness and weakness in the dog. Alternatively, tumors can rupture acutely and traumatically, leaving the dogs critically ill, weak, and at risk of death from blood loss. Immediate evaluation by a veterinarian is crucial to determine if surgery remains an option or if humane euthanasia is the best course of action.

Recovery and Management

Recovery and Management of Spleen Cancer in Dogs

Dogs undergoing splenectomy require standard postoperative care, including monitoring of the incision site and regular pain management. Typically, they will have a surgical incision extending from the sternum to the pelvis. These patients should limit activity and have their incisions monitored for at least 10-14 days.

Biopsy of all splenic tumors is essential for an accurate diagnosis. Surgery can be curative for benign tumors in the absence of other complications or illnesses.

For dogs with more advanced disease, follow-up appointments with surgeons and oncologists may be scheduled initially at 2 weeks, followed by visits every 1-3 months depending on the treatment plan. During these appointments, veterinarians will assess bloodwork, conduct chest x-rays, and perform ultrasounds to monitor disease progression and assess the patient’s quality of life.

Depending on the severity of the disease, certain complications may necessitate more intensive care and monitoring, including:

  • Persistent hemorrhaging and blood loss
  • Heart arrhythmias
  • Blood transfusions due to coagulation issues or blood loss
  • Low blood pressure resulting from blood loss
  • Nutritional support

Spleen Cancer in Dogs FAQs

How long do dogs live with spleen cancer?

The life expectancy of dogs with splenic cancer varies depending on the type and severity of the condition, ranging from weeks to months.

What are the implications for a dog with spleen cancer?

Dogs with spleen cancer are at significant risk of blood loss from a ruptured tumor, particularly those diagnosed with hemangiosarcoma.

Do dogs experience pain from spleen tumors?

Dogs may experience pain, especially if the tumor ruptures, although some cases may be asymptomatic.

Can spleen cancer in dogs be cured?

Certain types of splenic cancer can be curable through a combination of surgery and chemotherapy.

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