Lymphoma in dogs and cats: signs, diagnosis and treatment

Lymphoma in dogs is a cancer caused by an uncontrolled growth of lymphocytes, a type of white blood cell. Because lymphocytes travel through the body, lymphoma can involve lymph nodes, spleen, bone marrow and other organs.

The name covers a varied group of cancers rather than one identical disease. A dog's lymphoma may arise from B cells or T cells and can behave differently according to its type and location. [1]

Any dog can develop lymphoma, although it is diagnosed more often in middle-aged and older dogs. Some breeds appear more commonly affected, but breed alone cannot show whether an individual dog will develop it.

Age, body size and breed patterns can help describe groups of dogs, not diagnose a pet. A new lump or unexplained illness still needs to be assessed on its own features, whatever the dog's background. [1]

Dog lymphoma is most often multicentric, meaning several peripheral lymph nodes are involved, but it can also begin in the gut, chest, skin or another organ. These forms can look and behave quite differently.

Lymphoma outside the lymph nodes is called extranodal lymphoma. Possible sites include the eyes, kidneys, nervous system and bones, so the first signs may seem unrelated to a conventional lymph-node cancer. [1]

Some dog lymphomas are indolent and progress slowly, particularly certain forms affecting the spleen or lymph nodes. A dog may have few outward signs for a prolonged period even though abnormal lymphocytes are present.

Slow growing does not mean harmless, and it does not describe the more common aggressive forms. Cell type, tissue structure, affected site and change over time help a veterinary team judge the likely behaviour. [1]

Lymphoma commonly makes several lymph nodes feel enlarged, firm and usually painless. Owners may first notice smooth swellings under the jaw, in front of the shoulders or behind the knees while their dog otherwise seems well.

A lump cannot be identified as lymphoma by feel alone, because infections and other conditions can also enlarge lymph nodes. Sampling cells from an affected node is what helps distinguish cancer from other causes. [1]

Yes. A dog with lymphoma may become unusually tired or weak, lose weight or appetite, develop a fever, drink more, or seem dehydrated. Some dogs remain outwardly well when enlarged nodes are first noticed.

General illness tends to matter when judging how the dog is coping, but none of these signs is specific to lymphoma. Their pattern, speed of change and findings from an examination help guide the next tests. [1]

Intestinal lymphoma in dogs can cause poor appetite, vomiting, diarrhoea, weight loss and abdominal discomfort. A localised intestinal mass may partly or completely block the bowel, while more widespread disease can interfere with digestion and protein absorption.

These signs overlap with many non-cancerous digestive illnesses. Their persistence, combination and effect on hydration or body weight help a veterinary team decide whether blood tests, imaging and tissue sampling are needed. [1]

Lymphoma in a dog's chest can enlarge tissue around the thymus and nearby lymph nodes, leaving less room for the lungs or allowing fluid to collect around them. The dog may breathe harder or become less able to exercise.

Some affected dogs also develop high blood calcium, which can change thirst, urination, appetite and strength. Chest signs and calcium-related signs can occur together, but either pattern has other possible causes. [1]

Skin lymphoma in dogs can appear as one or more raised, sore or ulcerated lumps, or as widespread red, scaly and hairless patches. Changes may also involve the lips, gums or other junctions between skin and moist tissue.

Its appearance can resemble inflammatory or infectious skin disease, so a photograph or surface examination cannot confirm lymphoma. A tissue sample is usually needed to identify the cells and distinguish it from lookalike conditions. [1]

Lymphoma outside a dog's lymph nodes can cause signs linked to the organ involved, including sudden visual problems, seizures, kidney failure, breathing difficulty or bone pain. A weakened affected bone can occasionally fracture.

This wide range is why lymphoma cannot be recognised from one universal symptom list. The location of the problem guides examination, imaging and the safest place from which to obtain a diagnostic sample. [1]

Laboured breathing, open-mouth breathing, blue or grey gums, collapse, or a dog unable to settle because of breathlessness is an emergency and needs veterinary care immediately. Chest lymphoma can compress lung tissue or cause fluid to collect around the lungs.

Breathing effort can worsen quickly and cannot be assessed safely from a written symptom list. Even when lymphoma is only suspected, the immediate priority is stabilising the dog and finding the cause of the respiratory distress. [1]

A seizure, sudden blindness, collapse, inability to stand or rapidly worsening weakness in a dog with lymphoma needs urgent veterinary assessment. An ongoing seizure, severe unresponsiveness or breathing difficulty is an emergency requiring help immediately.

Lymphoma can affect the nervous system or eyes, but these signs also have many other serious causes. Prompt assessment focuses first on stabilisation, then on identifying whether cancer, treatment or another illness is responsible. [1]

Dog lymphoma is usually confirmed by examining cells from an enlarged lymph node or affected organ under a microscope. A fine-needle sample is often the first step, while a tissue biopsy may provide a fuller classification.

Blood tests and scans can show how the dog is coping and where disease may be present, but they do not usually identify lymphoma on their own. Additional tests can define the cell type and extent after confirmation. [2]

A dog may need a lymph-node biopsy when a needle sample is inconclusive, the cells are small or unusual, only one node is affected, or a fuller lymphoma classification would change clinical decisions.

A needle sample is often enough to recognise common high-grade nodal lymphoma. Biopsy preserves tissue architecture, allowing a pathologist to assess features such as pattern and grade that loose cells alone cannot show reliably. [3]

Immunophenotyping helps identify whether a dog's lymphoma cells are mainly B cells or T cells. That information refines the diagnosis and can contribute to treatment planning and a more individual discussion of likely behaviour.

It may be performed on tissue or a suitable cell sample using methods such as immunohistochemistry or flow cytometry. Other molecular tests can help confirm that a suspicious lymphocyte population is an abnormal clone. [4]

Staging describes how widely lymphoma is distributed in a dog's body and whether the dog has illness caused by it. The useful tests vary, but may include examination, blood and urine tests, chest imaging, abdominal ultrasound and selected tissue sampling.

More testing is not automatically better. Each staging test should have a clear chance of affecting prognosis, treatment choices or safe care, while also fitting the dog's needs and the owner's priorities. [2]

Most dog lymphomas are treated as body-wide disease, so chemotherapy is the main treatment rather than surgery alone. Radiation, surgery or specialist procedures can still have a role for particular localised, extranodal or indolent forms.

The plan depends on lymphoma type, affected sites, the dog's general health and the family's goals. Treatment may aim for remission and comfortable time even when a permanent cure is unlikely. [3]

Veterinary chemotherapy is planned around maintaining a dog's quality of life as well as controlling lymphoma. Many dogs tolerate it well, although nausea, vomiting, diarrhoea, reduced appetite and temporary bone-marrow suppression can occur.

Side effects and the cancer itself can both affect appetite, weight, energy and comfort. Regular reassessment allows the oncology team to balance cancer control with supportive care and the family's priorities for the dog. [5]

No. Remission means lymphoma has responded and its detectable signs have reduced or disappeared; it does not usually mean the cancer has been permanently cured. Most dogs with aggressive lymphoma are expected to relapse eventually.

A good remission can still give a dog meaningful time with improved wellbeing. Its depth and duration vary, and later choices depend on how the lymphoma returns, how the dog feels and how treatment was tolerated. [1]

A dog's lymphoma outlook depends on its anatomical form, cell type, grade, extent, the dog's health and whether the disease is already causing illness. Response to treatment also becomes an important part of the individual picture.

Published survival figures are group summaries and can differ greatly between lymphoma subtypes and treatment approaches. A diagnosis that includes classification and relevant staging gives a more useful discussion than the word lymphoma alone. [1]

Lymphoma in cats is a cancer of lymphocytes, immune-system cells found throughout the body. It can therefore develop in several organs rather than appearing only as enlarged lymph nodes.

Feline lymphoma is classified partly by where it is found and partly by the size and behaviour of the abnormal cells. Those distinctions matter because signs, tests, treatment and outlook vary between forms. [6]

Cat lymphoma commonly involves the gastrointestinal tract, chest, liver, spleen or kidneys, but it can also affect the nose, skin, eyes, nervous system or lymph nodes. The organ involved shapes the first signs an owner sees.

Most forms are considered capable of spreading through the body, although rare solitary sites can remain localised and some small-cell or splenic forms may progress slowly. Location alone does not fully predict behaviour. [3]

Small-cell intestinal lymphoma in cats is usually slower growing, while large-cell lymphoma is more aggressive and may form an intestinal mass. The distinction changes the likely treatment plan and outlook.

Cell size is determined by examining tissue under a microscope, not by how large a lump feels or how unwell the cat appears. Chronic signs can suggest a slower form, but they cannot confirm it. [7]

Yes. Intestinal lymphoma and inflammatory bowel disease can cause very similar signs and may also look alike on blood tests and ultrasound. No single symptom or routine test reliably separates them in every cat.

A diagnosis may require intestinal biopsies examined by a pathologist, with additional cell markers or clonality testing when the tissue changes remain difficult to classify. The result should be interpreted alongside the cat's whole clinical picture. [8]

A cat with lymphoma may lose weight or appetite, become less active, vomit, develop diarrhoea, breathe with difficulty, have nasal discharge, show a skin lump or develop a seizure. The exact signs depend on the affected site.

Some cats show only quiet, gradual changes and an examination can initially seem unremarkable. Because this list overlaps with many other illnesses, lymphoma is confirmed through appropriate sampling rather than symptoms alone. [7]

Intestinal lymphoma in cats can cause weight loss, vomiting, diarrhoea and either a reduced or increased appetite. A veterinary examination may find thickened bowel or an abdominal mass, but some affected cats have no obvious abnormality on examination.

The signs can develop slowly or quickly depending on the form. Normal blood results or an unremarkable ultrasound do not by themselves exclude intestinal lymphoma, so persistent digestive illness may need further investigation. [7]

Lymphoma in a cat's chest can cause difficult or faster breathing when enlarged tissue or fluid reduces the space available for the lungs. A cat may also become quiet, eat less or seem unable to get comfortable.

This form is called mediastinal lymphoma. Chest imaging can reveal a mass, enlarged internal lymph nodes or fluid, while a sample is needed to identify whether lymphoma is responsible. [6]

Nasal lymphoma in cats may cause ongoing nasal discharge or noisy, difficult breathing. Lymphoma elsewhere can appear as skin masses, eye problems, kidney illness or neurological changes, depending on which tissue is involved.

Cats are less likely than dogs to present with obvious enlarged peripheral lymph nodes. A site-specific sign therefore may be the first clue, and imaging plus a sample from the affected area usually guides diagnosis. [7]

Yes. Cats with kidney lymphoma can also have lymphoma involving the central nervous system, leading to behaviour changes, seizures or difficulty walking. These signs do not occur in every cat with renal disease.

Kidney and neurological signs can have several unrelated causes, so their appearance does not prove lymphoma has spread. Examination, blood and urine testing, imaging and carefully selected sampling help build the clinical picture. [6]

Open-mouth breathing, obvious abdominal effort, blue or grey gums, collapse, or a cat unable to settle because of breathlessness is an emergency and needs veterinary care immediately. Chest or nasal lymphoma can interfere with breathing.

Cats often conceal respiratory difficulty until it is significant, and the cause cannot be judged safely at home. The immediate clinical priority is oxygenation and stabilisation before tests identify whether lymphoma, fluid or another illness is responsible. [7]

A seizure, collapse, sudden inability to walk or rapidly worsening weakness in a cat with lymphoma needs urgent veterinary assessment. An ongoing seizure, severe unresponsiveness or breathing difficulty is an emergency requiring help immediately.

Kidney-associated or other lymphoma can involve the nervous system, but these signs also have many serious alternatives. Prompt assessment concentrates first on stabilisation and then on locating the cause. [6]

Cat lymphoma is diagnosed by examining cells or tissue from the affected site, usually through a fine-needle sample or biopsy. The best sampling method depends on where the disease is and how much classification is needed.

Some cases also need samples from internal organs or bone marrow, or molecular tests on blood or tissue. Scans help locate disease and choose a sampling site, but tissue or cells provide the diagnosis. [6]

A cat with suspected small-cell intestinal lymphoma may need intestinal biopsies because symptoms, scans and fine-needle samples often cannot separate it reliably from inflammatory bowel disease. Tissue structure is important to the diagnosis.

The biopsy route is chosen for the individual cat and the intestinal areas that need sampling. Pathology may be supplemented by cell-marker or clonality tests when inflammation and lymphoma remain difficult to distinguish. [7]

Blood chemistry, a blood-cell count, urine testing and feline leukaemia and immunodeficiency virus tests help show a cat's general health and factors that could affect treatment. They do not replace sampling of the suspected lymphoma.

The results can reveal organ involvement, other illness or a safer baseline for monitoring. Normal routine bloodwork is still possible, particularly with intestinal lymphoma, so a normal result does not settle the diagnosis. [6]

Staging looks for the extent and distribution of lymphoma in a cat and assesses the cat's overall health. Tests may include examination, blood and urine profiles, virus testing, chest X-rays, abdominal ultrasound and advanced imaging when the nervous system is involved.

The useful combination depends on the lymphoma's site and on whether a result would change prognosis, treatment or supportive care. Staging should be selected for the individual cat rather than treated as one fixed checklist. [3]

Cat lymphoma may be treated with chemotherapy, surgery, radiation therapy or a combination, depending on its type and location. Chemotherapy is common for body-wide disease, while a local intestinal mass or nasal lymphoma may need a different approach.

Treatment is tailored to the cat rather than chosen from the diagnosis name alone. Cell size, affected organs, general health, likely benefit and the family's quality-of-life priorities all help shape the plan. [6]

Veterinary chemotherapy is planned to control a cat's lymphoma while protecting quality of life. Many cats tolerate it well, although temporary nausea, vomiting, diarrhoea, reduced appetite, lethargy or bone-marrow suppression can occur.

The cancer itself can cause similar changes, so ongoing assessment matters. An oncology team can adapt supportive care and discuss whether the balance of benefit, burden and clinic visits still suits the individual cat and family. [5]

A cat's lymphoma outlook depends strongly on the affected site, whether the cells are small or large, how widely disease is present, the cat's health and response to treatment. One general survival figure cannot describe every form.

Remission means signs and detectable disease have reduced or disappeared, not that relapse is impossible. Small-cell intestinal disease often behaves very differently from aggressive large-cell or body-wide lymphoma, so a precise diagnosis supports a more useful discussion. [7]