CONDITION

Splenic Lymphoma

Splenic lymphoma is a form of cancer affecting the white blood cells within the spleen, the organ that filters blood and plays a role in immune function. The spleen becomes infiltrated with abnormal lymphocytes—cells that would normally help fight infection—and this can lead to enlargement, changes in blood counts, or disruption of the organ's normal work. Many dogs with splenic lymphoma show no outward signs at first, and the condition may be noticed during imaging or blood tests carried out for another reason. When signs do appear, they often include a quieter demeanour, reduced appetite, weight loss, or a sense that something has shifted in energy or routine. In some cases, the spleen becomes large enough to be felt during examination, or complications such as rupture or low platelet counts bring the condition to attention. This page explores the patterns that may signal splenic lymphoma, the mechanisms underlying the disease, the investigations used to characterise it, and the range of approaches that exist once a picture has formed.

Why this matters now

Splenic lymphoma tends to appear in middle-aged to older dogs, often between seven and ten years, though younger animals can be affected. Certain breeds, including Golden Retrievers, German Shepherds, and Boxers, appear more frequently in clinical reports, though the condition can occur in any dog. There is no clear environmental or nutritional trigger that has been consistently identified, and in many cases the disease develops without an obvious preceding event.

The progression of splenic lymphoma can vary considerably between individuals. Some dogs remain outwardly well for weeks or months while the disease advances quietly within the spleen, only becoming apparent when the organ has enlarged substantially or when blood abnormalities are noticed. In other cases, the disease progresses more rapidly, with signs emerging over a shorter timeframe, or complications such as rupture or severe anaemia bringing the condition to attention sooner. The pace and pattern of change often depend on the particular subtype of lymphoma and the overall response of the body to the growing cell population.

Signals & patterns

Early signals

Quieter energy or demeanour

The dog may seem less eager to engage in usual activities, taking longer to settle into walks or showing less interest in play. This shift can be subtle and easy to attribute to other causes, but it reflects the body's effort to manage an underlying process.

Reduced or selective appetite

Interest in food may wane, or the dog may eat smaller portions than usual. Some animals become more particular, accepting certain foods while declining others, a pattern that can emerge as the disease begins to affect overall wellbeing.

Gradual weight loss

Weight may decline slowly over weeks, often without dramatic change in appetite. This can be difficult to notice in dogs with longer coats or in households where multiple people share feeding responsibilities.

Mild abdominal distension

The abdomen may appear slightly fuller or rounder, particularly along the left side, as the spleen enlarges. This can be mistaken for weight gain or bloating, and may only become apparent when the dog is viewed from above or felt during handling.

Later signals

Pronounced abdominal swelling

The spleen can grow large enough to create visible asymmetry in the abdomen, and may be palpable as a firm mass. In some cases, the enlarged organ presses on other structures, contributing to discomfort or changes in posture.

Pale gums or mucous membranes

Anaemia may develop as the spleen's normal filtering work is disrupted or if abnormal cells interfere with blood cell production. The gums and inner eyelids may appear paler than usual, and the dog may tire more easily.

Collapse or acute weakness

In some cases, the spleen can rupture, leading to internal bleeding and sudden weakness or collapse. This represents a shift from a slowly evolving condition to a more immediate crisis, and the dog may seem unsteady, reluctant to stand, or visibly distressed.

Click to read about the biological mechanisms

How this is usually investigated

Investigation of suspected splenic lymphoma typically begins with observations from the history—changes in appetite, energy, or weight—and physical examination, which may reveal an enlarged spleen. Blood tests and imaging help characterise the size and structure of the organ and identify abnormalities in cell counts. A definitive picture usually requires sampling of the spleen itself, either through fine-needle aspiration or biopsy, to examine the cell population and determine the subtype of lymphoma.

Physical examination

Purpose: Palpation of the abdomen can reveal an enlarged spleen, though the degree of enlargement varies and subtle changes may not be detectable by hand alone.
Considerations: A normal examination does not rule out splenic lymphoma, particularly in the earlier stages when the organ may not yet be significantly enlarged or when the dog's body shape makes palpation difficult.

Blood tests (haematology and biochemistry)

Purpose: Full blood counts can show changes such as anaemia, low platelets, or abnormal white cell populations, while biochemistry may reveal secondary effects on liver or kidney function. Occasionally, abnormal lymphocytes are visible in the bloodstream.
Considerations: Blood tests provide context and may raise suspicion, but they cannot confirm the diagnosis or identify the specific subtype of lymphoma. Some dogs with splenic lymphoma have entirely normal blood results.

Abdominal ultrasound

Purpose: Ultrasound allows detailed examination of the spleen's internal structure, revealing whether the enlargement is diffuse or nodular, and whether other organs such as the liver or lymph nodes are involved.
Considerations: Ultrasound can suggest lymphoma but cannot distinguish it from other causes of splenic enlargement with certainty. The findings guide further sampling but do not replace it.

Fine-needle aspiration or core biopsy

Purpose: Sampling the spleen, either with a needle passed through the abdomen under ultrasound guidance or during surgery, provides cells or tissue for microscopic examination. This allows identification of the lymphocyte population and confirmation of lymphoma.
Considerations: Fine-needle aspiration is less invasive but may not always yield enough cells for complete classification. Core biopsy or surgical samples provide more architectural detail and are often needed to determine the subtype and grade of lymphoma.

Flow cytometry and immunophenotyping

Purpose: These laboratory techniques analyse the surface markers on lymphocytes to determine whether the lymphoma arises from B cells or T cells and to characterise the cell population more precisely.
Considerations: These tests require fresh samples and access to specialised laboratories. They provide valuable prognostic information but are not always available or necessary for initial management decisions.

Options & trade-offs

Management of splenic lymphoma is usually tailored to the individual dog, the subtype of lymphoma, and the goals and circumstances of the household. Some owners and vets pursue chemotherapy to slow disease progression, while others focus on managing symptoms and maintaining comfort as long as possible. Surgery, supportive care, and monitoring all have roles depending on the situation, and many approaches are used in combination.

Splenectomy (surgical removal of the spleen)

Removing the spleen can relieve the immediate effects of organ enlargement, reduce the risk of rupture, and provide tissue for detailed analysis. The procedure may be carried out as part of initial investigation or as a palliative measure to improve comfort. In some cases, splenectomy is combined with chemotherapy to address disease in other sites.

Trade-offs: Splenectomy does not cure lymphoma if cells are present elsewhere in the body, and the disease often progresses in the liver, bone marrow, or lymph nodes after surgery. The operation carries the usual risks of anaesthesia and abdominal surgery, and recovery takes several weeks.

Chemotherapy

Chemotherapy involves the use of drugs, often given in cycles over several months, to reduce the lymphoma cell population and slow disease progression. Protocols vary depending on the subtype and may include single agents or combinations. Treatment is typically given on an outpatient basis, with periodic monitoring of blood counts and organ function.

Trade-offs: Chemotherapy can extend the period during which a dog feels well, but it does not usually result in cure, and the disease tends to recur after weeks or months. Side effects such as nausea, diarrhoea, or suppression of blood cell production occur in some dogs, though many tolerate treatment without significant disruption.

Supportive care and monitoring

For some dogs, particularly those with slow-growing lymphoma or where chemotherapy is not pursued, management focuses on monitoring blood counts, managing symptoms such as nausea or lethargy with medications, and maintaining quality of life. This may include appetite support, pain relief if needed, and periodic reassessment to guide adjustments.

Trade-offs: This approach avoids the intensity and cost of chemotherapy but does not slow the disease process, and progression continues at a pace determined by the lymphoma itself. It suits households where frequent veterinary visits or medication administration are difficult, or where the dog's overall condition makes more active treatment less workable.

Corticosteroids

Prednisolone or similar drugs can reduce lymphoma cell numbers and improve symptoms such as appetite loss or lethargy, particularly in the short term. Steroids are sometimes used alone when chemotherapy is not feasible, or as part of a chemotherapy protocol.

Trade-offs: Corticosteroids can produce noticeable improvement in energy and appetite within days, but the effect tends to be temporary, and the lymphoma often becomes resistant after weeks or months. Prolonged use can lead to side effects such as increased thirst, urination, and susceptibility to infection.

Common misconceptions

Misconception:

"Removing the spleen will cure the lymphoma."

Reality:

Splenectomy removes the most obvious site of disease and can improve comfort, but lymphoma is often present in other tissues by the time the spleen is enlarged, and the disease typically continues to progress in the liver, bone marrow, or lymph nodes. Surgery is one part of management, not a cure in itself.

Misconception:

"Chemotherapy for dogs is as harsh as chemotherapy for humans."

Reality:

Veterinary chemotherapy protocols are generally designed to minimise side effects and maintain quality of life rather than to aim for cure at any cost. Most dogs tolerate treatment well, with fewer and milder side effects than are often seen in human oncology, though individual responses vary.

Misconception:

"If blood tests are normal, the spleen cannot have lymphoma."

Reality:

Blood tests reflect what is circulating and how the bone marrow is responding, not necessarily what is happening within the spleen itself. Many dogs with splenic lymphoma have unremarkable blood results, particularly in the earlier stages, and diagnosis depends on imaging and sampling of the organ.

Related conditions

Multicentric Lymphoma in Dogs

Multicentric lymphoma and splenic lymphoma are both forms of lymphoma in which abnormal lymphocytes proliferate, but differ in the primary sites affected. In some cases, multicentric disease may involve the spleen alongside lymph nodes, and patterns of investigation and treatment often overlap.

Splenic Mass

Splenic lymphoma is one of several conditions that can present as a mass within the spleen. Imaging alone cannot reliably distinguish lymphoma from other causes of splenic enlargement, so tissue sampling is often needed to characterise the nature of the growth.

Hemangiosarcoma

Haemangiosarcoma and splenic lymphoma are both conditions that can cause enlargement of the spleen and may be discovered during investigation of vague signs or abdominal imaging. The two conditions differ in their cellular origin and behaviour, but both can lead to complications such as rupture or changes in blood counts.

Multiple Myeloma

Multiple myeloma and splenic lymphoma both arise from abnormal proliferation of white blood cells, though they involve different cell types—plasma cells in myeloma and lymphocytes in lymphoma. Both can affect blood counts, produce abnormal proteins, and require similar investigative approaches including blood work and imaging.

Cutaneous Lymphoma

Cutaneous lymphoma and splenic lymphoma represent different anatomical patterns of lymphoma, with one primarily affecting the skin and the other the spleen. In some cases, lymphoma can involve multiple sites over time, and understanding the extent of disease can guide decisions about monitoring and management.

Understanding how splenic lymphoma fits into the broader picture of a dog's health can help frame the choices ahead. The longevity and healthspan content explores how age, immune function, and organ reserves interact, and how different conditions influence the arc of an older dog's life. Observations around appetite, energy, and weight often overlap with other age-related changes, and mapping these patterns over time can be a useful conversation to have at the next appointment.