Lymphoma in Cats: Symptoms, Types, Diagnosis, Treatment and Prognosis

Lymphoma in Cats: Symptoms, Types, Diagnosis, Treatment and Prognosis

By Dr Duncan Houston

Lymphoma in cats is not one disease with one predictable outcome.

A cat with lymphoma may present with chronic vomiting, enlarged kidneys, a blocked nose, breathing difficulty, seizures, skin lesions or little more than gradual weight loss. Some forms progress slowly and can be controlled for years. Others are aggressive and can make a cat critically unwell within days or weeks.

What matters most is where the lymphoma is located, whether it is low-grade or high-grade, and how well the cat responds to treatment.

Quick Answer

Lymphoma is a cancer of lymphocytes, which are immune-system cells found throughout the body. In cats, it most commonly affects the gastrointestinal tract but may also involve the kidneys, chest, nose, liver, spleen, skin, eyes, nervous system or lymph nodes.

Diagnosis usually requires cytology or biopsy. Ultrasound can identify suspicious changes but cannot reliably confirm every form of lymphoma, particularly low-grade intestinal lymphoma. Treatment may involve oral medication, injectable chemotherapy, radiation therapy, surgery for selected local complications and supportive care.

What Is Lymphoma in Cats?

Lymphoma develops when a population of lymphocytes begins dividing uncontrollably.

Lymphocytes are normally involved in immune defence. They circulate through the blood and are also found within lymph nodes, the intestinal tract, spleen, liver, bone marrow and many other tissues.

Lymphoma may arise from:

• B lymphocytes

• T lymphocytes

• Less commonly, other specialised lymphoid cells

Some feline lymphomas remain largely confined to one anatomical area, particularly certain nasal or skin lymphomas. Many others have the potential to involve multiple organs, even when one site is producing most of the clinical signs.

Lymphoma is one of the most commonly diagnosed cancers in cats. A large UK primary-care study found that alimentary lymphoma was the most frequent anatomical form, followed by other abdominal forms and renal lymphoma. Most affected cats were older, although mediastinal lymphoma occurred in a younger population.

What Is the Difference Between Low-Grade and High-Grade Lymphoma?

The grade describes how abnormal and rapidly dividing the lymphoma cells appear.

Low-grade lymphoma

Low-grade lymphoma is usually composed of small, mature-looking lymphocytes.

It generally:

• Progresses slowly

• Causes signs over several months

• Is most commonly found in the intestinal tract

• May be difficult to distinguish from chronic inflammatory enteropathy

• Is often managed with oral prednisolone and chlorambucil

• Can remain controlled for a year or considerably longer

Low-grade intestinal lymphoma is now more specifically described as low-grade intestinal T-cell lymphoma in many pathology reports.

Intermediate or high-grade lymphoma

Intermediate and high-grade lymphoma usually contains larger, more immature and rapidly dividing cells.

It is more likely to:

• Progress over days or weeks

• Form distinct masses

• Cause severe systemic illness

• Invade several organs

• Require injectable multiagent chemotherapy

• Relapse earlier than low-grade disease

High-grade disease can respond rapidly to chemotherapy, but its remission is often less durable. Current AAHA guidance gives a broad median survival range of approximately six to nine months for cats receiving CHOP-type chemotherapy, although outcomes vary considerably between anatomical forms and individual cats.

Large granular lymphocyte lymphoma

Large granular lymphocyte lymphoma is a distinct and generally aggressive subtype. It often affects the intestine, mesenteric lymph nodes, liver or spleen.

Published cohorts have reported poor chemotherapy response and short survival in many affected cats, although occasional long-term responses occur in carefully selected patients.

What Are the Main Types of Feline Lymphoma?

Anatomical form	Common warning signs	Typical diagnostic approach	Common treatment pattern
Low-grade intestinal lymphoma	Chronic weight loss, vomiting, diarrhoea or appetite change	Blood tests, ultrasound and intestinal biopsies	Prednisolone and chlorambucil
High-grade intestinal lymphoma	Rapid weight loss, vomiting, reduced appetite, abdominal mass or obstruction	Ultrasound, cytology or biopsy	Multiagent chemotherapy, with surgery for selected masses or obstruction
Renal lymphoma	Increased thirst, vomiting, appetite loss, weight loss and enlarged kidneys	Ultrasound and kidney, lymph node, liver or spleen sampling	Multiagent chemotherapy
Mediastinal lymphoma	Rapid or difficult breathing, chest fluid, reduced appetite and weakness	Chest imaging, fluid analysis and mass sampling	Multiagent chemotherapy
Nasal lymphoma	One-sided nasal discharge, nosebleeds, noisy breathing or facial swelling	Head CT and nasal biopsy	Radiation therapy, chemotherapy or both
Hepatic or splenic lymphoma	Appetite loss, weight loss, vomiting, jaundice or enlarged abdomen	Ultrasound and organ sampling	Systemic chemotherapy
Multicentric lymphoma	Several enlarged lymph nodes or multiple affected organs	Lymph node or organ cytology and staging	Systemic chemotherapy
Central nervous system lymphoma	Seizures, weakness, circling, balance changes or paralysis	MRI, cerebrospinal fluid testing and sometimes biopsy	Chemotherapy, radiation therapy or both
Ocular lymphoma	Cloudy eyes, inflammation, vision loss or abnormal pupils	Eye examination and ocular sampling	Systemic treatment with local eye therapy when needed
Cutaneous lymphoma	Nodules, plaques, ulcers, hair loss or thickened skin	Skin biopsy	Surgery, radiation or systemic medication depending on distribution

The site of disease often has as much influence on treatment and prognosis as the general word “lymphoma”.

What Are the Symptoms of Lymphoma in Cats?

The symptoms depend on which organs are affected.

General signs may include:

• Weight loss

• Reduced appetite

• Increased appetite with continued weight loss

• Lethargy

• Hiding

• Muscle loss

• Vomiting

• Diarrhoea

• Dehydration

• Pale gums

• Fever

• Poor coat condition

• Reduced grooming

• Recurrent infections

• Enlarged lymph nodes

• A palpable abdominal mass

These signs are not specific to lymphoma. Kidney disease, hyperthyroidism, pancreatitis, chronic enteropathy, infection and several other cancers can produce an almost identical pattern.

Gastrointestinal signs

Intestinal lymphoma may cause:

• Chronic or intermittent vomiting

• Diarrhoea

• Constipation

• Weight loss

• Reduced appetite

• Excessive appetite

• Abdominal discomfort

• Flatulence

• Low cobalamin

• Poor muscle condition

Some cats with substantial intestinal lymphoma have no diarrhoea. Others continue eating reasonably well despite progressive weight loss.

Kidney-related signs

Renal lymphoma may cause:

• Increased thirst

• Increased urination

• Reduced appetite

• Vomiting

• Weight loss

• Dehydration

• Weakness

• Enlarged or irregular kidneys

• Sudden deterioration in kidney values

Renal lymphoma can affect both kidneys and may occur alone or as part of multicentric disease.

Chest-related signs

Mediastinal lymphoma may cause:

• Rapid breathing

• Increased breathing effort

• Open-mouth breathing

• Reduced exercise tolerance

• Difficulty settling

• Pleural fluid

• Regurgitation

• Reduced appetite

• Weakness

• Collapse

Breathing changes associated with mediastinal lymphoma can become an emergency before the cancer diagnosis has been confirmed.

Nasal signs

Nasal lymphoma may cause:

• Persistent discharge from one nostril

• Sneezing

• Recurrent nosebleeds

• Noisy breathing

• Reduced nasal airflow

• Facial swelling

• Eye discharge

• Reduced appetite due to impaired smell

These signs may also be caused by fungal infection, chronic rhinitis, a foreign body or another nasal tumour. Imaging cannot determine the tumour type reliably, so biopsy remains essential.

Neurological signs

Central nervous system lymphoma may cause:

• Seizures

• Circling

• Head tilt

• Poor balance

• Weakness

• Paralysis

• Behavioural change

• Reduced awareness

• Abnormal pupil size

• Sudden blindness

Neurological lymphoma carries a guarded prognosis, although the outcome depends on whether disease is confined to one site and whether radiation or chemotherapy can be delivered.

How Worried Should You Be?

Risk level	What you may notice	Recommended action
Stable but time-sensitive	Gradual weight loss, occasional vomiting or a small lump, while your cat remains bright and eating	Arrange a veterinary examination within the next few days
Needs prompt investigation	Persistent vomiting, diarrhoea, appetite change, enlarged kidneys, one-sided nasal discharge or progressive weight loss	Arrange assessment within 24 to 72 hours
Same-day concern	Eating very little, repeated vomiting, marked lethargy, jaundice, significant weakness, rapid tumour growth or painful abdominal signs	Seek same-day veterinary care
Critical	Open-mouth breathing, severe breathing effort, collapse, seizures, sudden blindness, inability to stand or reduced consciousness	Go to an emergency veterinary hospital immediately

A cat does not need to be dramatically unwell before lymphoma deserves investigation. Chronic weight or muscle loss in an older cat is enough reason to start looking for an underlying disease.

What Causes Lymphoma in Cats?

Most cases do not have one identifiable cause.

Feline lymphoma probably develops through a combination of:

• Accumulated genetic changes

• Age-related cellular damage

• Viral influences

• Chronic immune stimulation

• Individual susceptibility

• Environmental factors that remain incompletely understood

Developing lymphoma is not evidence that an owner fed the wrong food or missed one obvious preventive step.

What Is the Link Between FeLV and Lymphoma?

Feline leukaemia virus has a well-established relationship with lymphoma, particularly some high-grade and mediastinal forms.

FeLV-associated lymphoma historically caused a strong peak in young cats. The frequency of FeLV-antigen-positive lymphoma has fallen substantially in many regions following testing, vaccination and reduced exposure. Most modern feline lymphoma cases in several populations are FeLV antigen-negative, but FeLV remains clinically important and is considered a negative prognostic factor.

A negative FeLV test does not rule out lymphoma.

A positive result may influence:

• Prognosis

• Chemotherapy planning

• Infection control

• Management of other cats

• Interpretation of blood-cell abnormalities

Current oncology guidance recommends FeLV and FIV testing during the feline lymphoma work-up.

Is Mediastinal Lymphoma Always FeLV-Positive?

No.

FeLV remains an important association, particularly in young cats with high-grade mediastinal lymphoma. However, FeLV-negative mediastinal lymphoma is also well recognised.

One study of 38 cats with mediastinal lymphoma reported an overall treatment response of almost 95% and a median survival of 373 days. Another cohort of FeLV-antigen-positive cats treated with COP chemotherapy had a median survival of 338 days. These results show that FeLV status matters, but it does not tell the entire story.

Can Chronic Intestinal Inflammation Turn Into Lymphoma?

A relationship between chronic inflammatory enteropathy and low-grade intestinal lymphoma has been proposed, but the exact sequence remains uncertain.

Inflammatory and neoplastic lymphocytes may coexist within the same intestine. Up to 60% of low-grade intestinal lymphoma cases in some studies have had inflammatory lesions in the same or another intestinal section.

This does not prove that every cat with inflammatory bowel disease will develop lymphoma. It does mean that chronic vomiting, diarrhoea or weight loss should not be left indefinitely without reassessment when the cat stops responding as expected.

How Do Vets Diagnose Lymphoma in Cats?

The diagnostic plan should answer four questions:

1. Is lymphoma actually present?

2. Which organs are involved?

3. Is it low-grade or high-grade?

4. Will further staging change treatment or prognosis?

1. History and Physical Examination

Your veterinarian will ask about:

• Appetite

• Weight change

• Vomiting

• Stool quality

• Thirst and urination

• Breathing

• Nasal discharge

• Activity

• Neurological changes

• Medication

• FeLV and FIV status

• Previous intestinal or inflammatory disease

The examination may identify:

• Thickened intestines

• An abdominal mass

• Enlarged kidneys

• Enlarged liver or spleen

• Peripheral lymph node enlargement

• Chest fluid

• Nasal airflow reduction

• Eye abnormalities

• Skin lesions

• Muscle loss

• Dehydration

The absence of palpable lymph nodes does not make lymphoma unlikely in a cat. Feline lymphoma often begins within internal organs rather than the easily felt lymph nodes commonly affected in dogs.

2. Blood and Urine Testing

Initial testing commonly includes:

• Complete blood count

• Blood smear

• Serum biochemistry

• Electrolytes

• Albumin and total protein

• Kidney and liver values

• Calcium

• Urinalysis

• FeLV testing

• FIV testing

Additional tests may include:

• Total T4

• Cobalamin and folate

• Feline pancreatic lipase

• Feline trypsin-like immunoreactivity

• Urine culture

• Blood pressure

• Coagulation testing

These tests help identify organ dysfunction, anaemia, infection, dehydration and other conditions that may affect anaesthesia or chemotherapy.

Normal bloodwork does not rule out lymphoma.

3. Diagnostic Imaging

Imaging is selected according to the suspected location.

Possible tests include:

• Abdominal ultrasound

• Chest radiographs

• Thoracic ultrasound

• Head CT

• Chest or abdominal CT

• MRI of the brain or spinal cord

• Echocardiography in selected cats

Imaging identifies suspicious tissue and helps guide sampling, but it rarely replaces cytology or histopathology.

Current oncology guidelines recommend selecting staging tests according to whether the result will change prognosis or treatment, rather than performing every possible scan automatically.

4. Fine-Needle Aspiration and Cytology

Fine-needle aspiration may provide a rapid diagnosis when lymphoma affects:

• An enlarged lymph node

• A discrete intestinal mass

• A kidney

• The liver

• The spleen

• A mediastinal mass

• A skin or subcutaneous lesion

High-grade lymphoma is often easier to recognise because the cells are large and clearly abnormal.

Low-grade lymphoma is much more difficult. An aspirate containing many small lymphocytes may look similar whether the tissue is normal, inflamed or neoplastic. A mesenteric lymph node aspirate cannot reliably distinguish low-grade intestinal lymphoma from chronic inflammatory enteropathy.

5. Biopsy and Histopathology

Biopsy provides tissue architecture, which is essential for diagnosing many forms of lymphoma.

Histopathology may reveal:

• Cell size

• Pattern of invasion

• Tissue destruction

• Histological grade

• Intestinal wall distribution

• Whether inflammation and lymphoma coexist

For chronic intestinal disease, intestinal biopsy remains the current gold standard for distinguishing lymphoplasmacytic enteritis from low-grade intestinal T-cell lymphoma.

Endoscopic biopsy

Advantages include:

• Less invasive than abdominal surgery

• Direct visualisation of the stomach and intestinal lining

• Shorter recovery

• Ability to obtain numerous mucosal samples

Limitations include:

• Inability to sample much of the jejunum

• Inability to assess every full-thickness or external lesion

• Risk of inadequate or poorly oriented samples

• Difficulty reaching some ileal lesions

Surgical or laparoscopic biopsy

Advantages include:

• Full-thickness intestinal samples

• Access to the jejunum

• Ability to sample the liver, pancreas and lymph nodes

• Ability to inspect the entire abdomen

• Ability to remove a focal obstructive mass

Limitations include:

• General anaesthesia

• Abdominal surgery

• Longer recovery

• Risk of intestinal leakage or wound complications

• Potential delay before chemotherapy begins

No biopsy method is automatically superior in every cat. Good sample number, depth, orientation and pathology interpretation matter as much as the method used.

6. Immunohistochemistry

Immunohistochemistry uses tissue markers to determine which types of lymphocytes are present.

It may help identify whether the infiltrate is:

• Predominantly T-cell

• Predominantly B-cell

• Mixed and more suggestive of inflammation

• Monomorphic and more suggestive of lymphoma

It is especially helpful when routine histopathology is ambiguous.

Immunohistochemistry still cannot provide absolute certainty in every intestinal case because lymphoma and inflammation may occur together.

7. PARR and Clonality Testing

PCR for antigen receptor rearrangement, usually shortened to PARR, looks for a dominant lymphocyte clone.

A clonal result can support lymphoma, but clonality does not automatically equal cancer. Reactive immune responses may also produce clonal populations.

PARR should be interpreted alongside:

• Clinical signs

• Imaging

• Histopathology

• Immunohistochemistry

• Tissue distribution

• Treatment response

The ACVIM consensus warns that PARR specificity may be substantially lower when the real clinical question is inflammatory enteropathy versus low-grade intestinal lymphoma. It should not be used as a stand-alone verdict.

8. Staging

Staging looks for disease beyond the main affected site.

It may include:

• Chest radiographs

• Abdominal ultrasound

• Lymph node sampling

• Liver or spleen sampling

• Bone marrow sampling

• CT or MRI

• Cerebrospinal fluid analysis

• Eye examination

Not every cat needs a bone marrow aspirate or every available imaging test.

Staging is most useful when the result would:

• Change the treatment protocol

• Alter prognosis

• Identify a safer biopsy site

• Affect radiation planning

• Show that apparently local disease is systemic

Why Ultrasound Alone Cannot Diagnose Intestinal Lymphoma

Ultrasound findings associated with intestinal lymphoma may include:

• Thickening of the muscular layer

• Loss of normal wall layering

• A focal intestinal mass

• Enlarged mesenteric lymph nodes

• Reduced intestinal movement

• Abdominal fluid

Unfortunately, several of these changes also occur with chronic inflammatory enteropathy.

There is currently no single clinical sign, blood result, imaging change or biomarker that reliably distinguishes lymphoplasmacytic enteritis from low-grade intestinal lymphoma. The strongest diagnosis comes from integrating clinical findings with well-collected biopsy specimens, histopathology and selected ancillary testing.

The phrase “the ultrasound looks like lymphoma” should therefore mean that lymphoma is a serious differential diagnosis, not that the cancer has been definitively confirmed.

Low-Grade Intestinal Lymphoma

Low-grade intestinal lymphoma often affects older cats and progresses gradually.

Typical signs include:

• Chronic weight loss

• Intermittent vomiting

• Variable appetite

• Soft stool or diarrhoea

• Constipation

• Poor muscle condition

• Low cobalamin

• Mild intestinal thickening

A cat may have shown signs for months before diagnosis. Temporary improvement with diet, anti-nausea medication or corticosteroids does not reliably distinguish inflammation from lymphoma.

How is it treated?

The standard treatment is usually:

• Prednisolone

• Chlorambucil

• Cobalamin supplementation when required

• Nutritional support

• Treatment of nausea or diarrhoea

• Monitoring of blood-cell counts

This treatment is commonly administered at home.

AAHA reports survival ranging from approximately eight months to more than two years. Individual studies have reported median survival around 19 to 29 months, with substantially longer outcomes in cats that achieve complete clinical remission.

Does treatment need to continue forever?

Protocols vary.

Some oncologists use a defined treatment course and stop chlorambucil after sustained remission. Others continue lower-frequency treatment for longer.

The decision depends on:

• Clinical response

• Body weight

• Blood results

• Ultrasound findings

• Relapse risk

• Drug tolerance

Chlorambucil can suppress bone marrow function, so regular complete blood counts remain important even when the cat appears well.

High-Grade Intestinal Lymphoma

High-grade intestinal lymphoma generally develops more rapidly.

Signs may include:

• Sudden or progressive appetite loss

• Frequent vomiting

• Rapid weight loss

• Abdominal pain

• A palpable mass

• Intestinal obstruction

• Gastrointestinal bleeding

• Perforation and peritonitis

Cytology may provide a diagnosis when a discrete mass or enlarged lymph node can be sampled.

How is it treated?

Treatment usually involves multiagent chemotherapy, such as:

• COP

• CHOP

• L-CHOP

• Another oncology-designed multiagent protocol

A recent study of 55 cats with intermediate to high-grade alimentary lymphoma treated with a VAPC multiagent protocol reported a complete response in 68% of cats with measurable disease and a median progression-free survival of 184 days. Cats achieving complete remission had substantially longer outcomes than non-responders.

Is surgery needed?

Surgery is not routinely used to remove diffuse intestinal lymphoma.

It may be recommended when there is:

• A discrete resectable mass

• Intestinal obstruction

• Perforation

• Severe local bleeding

• A need for full-thickness diagnosis

• A high risk of the intestine rupturing during treatment

In one selected group of 20 cats with discrete high-grade gastrointestinal lymphoma, surgical resection followed by CHOP-based chemotherapy produced a median survival of 417 days. These cats were carefully selected and the result should not be applied to diffuse or unresectable disease.

Renal Lymphoma

Renal lymphoma may affect one or both kidneys.

Ultrasound may show:

• Diffusely enlarged kidneys

• Irregular kidney shape

• Hypoechoic cortical tissue

• Nodules or masses

• Tissue surrounding the kidneys

• Abdominal lymph node enlargement

Kidney values may be normal early in the disease and significantly increased later.

How is it diagnosed?

Diagnosis may involve aspiration of:

• The kidney

• A regional lymph node

• The liver

• The spleen

• Another accessible lesion

Kidney aspiration must be planned carefully because not every enlarged or abnormal kidney should be sampled in the same way.

How is it treated?

Multiagent chemotherapy is generally recommended.

In a study of 27 cats with renal lymphoma, cats receiving an L-CHOP-based protocol had a median lymphoma-related survival of 203 days, compared with 50 days for cats receiving corticosteroids alone. The ranges were extremely wide, and occasional long-term survivors occurred.

Renal lymphoma has historically been associated with possible nervous-system involvement, but the true frequency is uncertain. New neurological signs in a cat with renal lymphoma warrant urgent investigation.

Mediastinal Lymphoma

Mediastinal lymphoma develops within the chest, commonly near the thymus or cranial mediastinal lymph nodes.

It may compress:

• The lungs

• Major blood vessels

• The oesophagus

• The trachea

Pleural fluid may further restrict lung expansion.

How is it diagnosed?

Diagnosis may be obtained from:

• Pleural fluid cytology

• Ultrasound-guided mass aspiration

• CT-guided sampling

• Lymph node sampling

The immediate priority may be stabilising breathing and removing chest fluid before a complete cancer work-up is performed.

How is it treated?

Treatment generally involves multiagent chemotherapy.

Published treated cohorts have reported high initial response rates and median survival around nine to twelve months, although FeLV status, age, remission quality and disease extent influence individual outcomes.

A cat that is struggling to breathe needs emergency stabilisation. Chemotherapy planning comes after oxygenation and chest expansion are addressed.

Nasal Lymphoma

Nasal lymphoma often behaves more like a local tumour than many other feline lymphoma forms.

Signs include:

• Discharge from one nostril

• Nosebleeds

• Sneezing

• Noisy breathing

• Facial swelling

• Reduced appetite

• Eye or tear-duct changes

How is it diagnosed?

The preferred work-up commonly includes:

• Head CT

• Nasal biopsy

• FeLV and FIV testing

• Chest imaging

• Abdominal imaging

• Regional lymph node assessment

CT shows the location and extent of disease but cannot reliably distinguish lymphoma from carcinoma, fungal infection or severe inflammation.

How is it treated?

Radiation therapy is often an excellent local treatment.

Chemotherapy may be used:

• Alone

• With radiation

• When disease is found elsewhere

• When radiation is unavailable

• After relapse

A study of 19 cats treated with radiation and chemotherapy reported a median survival of 955 days. Another large extranodal lymphoma study found that cats with nasal lymphoma achieving complete remission had a median survival of 749 days. Current AAHA guidance notes that nasal lymphoma may be controlled for more than two years in some cats receiving radiation.

These results make nasal lymphoma one of the more treatable feline lymphoma locations when the cat can receive appropriate local therapy.

Multicentric, Hepatic and Splenic Lymphoma

Multicentric lymphoma affects multiple lymph nodes or organs.

Possible signs include:

• Generalised lymph node enlargement

• Weight loss

• Fever

• Reduced appetite

• Pale gums

• Enlarged liver or spleen

• Abdominal swelling

• Blood-cell abnormalities

• Jaundice

Hepatic or splenic lymphoma may occur as part of multicentric disease or be the dominant anatomical presentation.

Diagnosis often involves fine-needle aspiration or biopsy of the affected organ. Treatment is generally systemic chemotherapy rather than surgical removal of one organ alone.

Central Nervous System Lymphoma

Lymphoma may affect the brain, spinal cord, meninges or several nervous-system locations.

Possible signs include:

• Seizures

• Circling

• Behavioural change

• Weakness

• Paralysis

• Spinal pain

• Poor balance

• Head tilt

• Vision changes

• Reduced consciousness

MRI is generally the preferred imaging test.

Further investigation may include:

• Cerebrospinal fluid analysis

• Sampling of disease elsewhere

• Biopsy in selected cases

• FeLV and FIV testing

Treatment may involve chemotherapy capable of reaching the nervous system, radiation therapy or both. Outcomes are variable and are often guarded, particularly when neurological impairment is severe or systemic disease is present.

Ocular Lymphoma

Ocular lymphoma may affect one or both eyes.

Signs may include:

• Cloudiness

• Redness

• Eye pain

• Dilated pupils

• Retinal changes

• Sudden blindness

• Recurrent uveitis

• Bleeding within the eye

Ocular lymphoma may be localised temporarily but commonly warrants investigation for systemic disease.

Treatment may involve:

• Systemic chemotherapy

• Anti-inflammatory eye medication

• Radiation

• Surgical removal of a blind, painful eye in selected cases

Persistent or unusual uveitis in an older cat deserves more than repeated topical treatment when the expected response does not occur.

Cutaneous and Subcutaneous Lymphoma

Cutaneous lymphoma may appear as:

• Nodules

• Plaques

• Ulcers

• Scaling

• Hair loss

• Thickened skin

• Red or depigmented paw pads

Some forms remain relatively localised, while others are aggressive and spread.

Subcutaneous lymphoma has been associated with frequent local recurrence and distant progression. One large study reported a median survival of 148 days, although biological behaviour differs between histological subtypes.

Diagnosis requires skin or subcutaneous tissue biopsy. A superficial aspirate may not provide enough information to classify the disease correctly.

How Is Feline Lymphoma Treated?

Treatment depends on the exact form.

Treatment	Main use
Prednisolone alone	Palliative care when chemotherapy is declined or unsuitable
Prednisolone and chlorambucil	Low-grade intestinal lymphoma
COP or CHOP-type chemotherapy	High-grade, systemic, renal, mediastinal and many other forms
Lomustine or other single agents	Selected first-line or rescue situations
Radiation therapy	Nasal lymphoma, central nervous system disease and selected localised lesions
Surgery	Obstruction, perforation, solitary removable disease or diagnostic biopsy
Supportive care	Nausea, appetite loss, pain, dehydration, low cobalamin and nutritional support

Current AAHA guidance reports a median survival of approximately two to three months with prednisolone alone, compared with approximately six to nine months for CHOP-type protocols across broader high-grade feline lymphoma populations. Low-grade gastrointestinal and localised nasal lymphoma often have considerably longer outcomes.

Is Prednisolone Alone a Reasonable Treatment?

It can be reasonable when the goal is palliation.

Prednisolone may:

• Improve appetite

• Reduce inflammation

• Temporarily shrink lymphoma

• Improve comfort

• Reduce vomiting or diarrhoea

It rarely provides durable control of high-grade lymphoma by itself.

When the cat is clinically stable enough, diagnostic samples should ideally be collected before prednisolone begins. Starting treatment before confirming the location and grade may leave the veterinary team with less information when planning longer-term therapy.

If emergency treatment cannot wait, stabilising the cat takes priority over obtaining a perfect diagnostic sample.

How Well Do Cats Tolerate Chemotherapy?

Cats generally tolerate veterinary chemotherapy better than many owners expect.

The goal is not to deliver the highest possible drug dose. It is to control the cancer while preserving appetite, activity and quality of life.

AAHA estimates that approximately 10% to 15% of cats experience chemotherapy side effects, with severe reactions occurring in fewer than 5% of cases.

Possible adverse effects include:

• Reduced appetite

• Nausea

• Vomiting

• Diarrhoea

• Lethargy

• Low white blood cell counts

• Infection

• Anaemia

• Low platelets

• Hair or whisker changes

• Drug-specific kidney, liver or bladder effects

Complete blood counts are used to determine whether treatment should proceed, be delayed or be dose-adjusted.

Unlike people receiving some human chemotherapy protocols, cats do not generally lose all their fur. Shaved areas and whiskers may regrow differently, and some long-haired breeds may develop coat changes.

What Supportive Care May Be Needed?

Supportive care is part of cancer treatment, not an optional extra.

It may include:

• Anti-nausea medication

• Appetite stimulants

• Fluid therapy

• Cobalamin supplementation

• Pain relief

• Diarrhoea management

• Nutritional support

• Antibiotics for documented infection

• Blood transfusion

• Oxygen

• Drainage of chest fluid

• Feeding-tube placement

If appetite remains poor despite control of nausea and pain, a feeding tube may be recommended. Early nutritional support can help preserve muscle and allow time for chemotherapy to work.

Raw diets are generally not recommended for immunocompromised oncology patients because of bacterial contamination risk. A complete, palatable diet that the cat will reliably eat is more useful than chasing an unsupported “anti-cancer” food.

What Is the Prognosis for a Cat With Lymphoma?

There is no single feline lymphoma survival time.

Lymphoma form	Broad published outcome
Low-grade intestinal lymphoma	Commonly 18 months to more than 2 years, with substantial individual variation
High-grade or systemic lymphoma treated with multiagent chemotherapy	Commonly around 6 to 9 months
High-grade discrete intestinal lymphoma treated with surgery and chemotherapy	Median 417 days in one selected study
Renal lymphoma	Median 203 days with L-CHOP in one cohort, but occasional long-term survival
Mediastinal lymphoma	Approximately 9 to 12 months in several treated cohorts
Nasal lymphoma	Frequently 1.5 to more than 2 years following successful local treatment
Large granular lymphocyte lymphoma	Often measured in weeks to a few months
Central nervous system lymphoma	Highly variable but generally guarded
Prednisolone alone for high-grade disease	Commonly around 2 to 3 months

These figures come from different retrospective populations and cannot be compared as though every study involved the same cats, stage or treatment.

The factors that matter most include:

• Anatomical location

• Low-grade versus high-grade disease

• Ability to achieve complete remission

• FeLV status

• Disease stage

• Whether the cat is clinically unwell at diagnosis

• Blood-cell abnormalities

• Kidney or liver dysfunction

• Ability to tolerate treatment

• Continued food intake and body weight

Across several feline lymphoma studies, cats achieving complete remission have lived substantially longer than cats achieving only partial response or no response.

A median is not an expiry date. Some cats progress much earlier, while a meaningful minority substantially outlive the published middle value.

When Is Feline Lymphoma an Emergency?

Go to an emergency veterinary hospital immediately if your cat develops:

• Open-mouth breathing

• Marked breathing effort

• Blue or grey gums

• Collapse

• Inability to stand

• Seizures

• Sudden blindness

• Severe disorientation

• Reduced consciousness

• Repeated vomiting with profound weakness

• A painful, distended abdomen

• Inability to keep water down

• Uncontrolled bleeding

• Extremely pale gums

• Sudden paralysis

• Severe spinal pain

• Rapid deterioration after chemotherapy

Seek same-day care if your cat:

• Has eaten almost nothing for approximately 24 hours

• Is repeatedly vomiting

• Has persistent diarrhoea and dehydration

• Develops a fever or profound lethargy after chemotherapy

• Has worsening nasal obstruction

• Shows increasing abdominal pain

• Is losing weight rapidly

• Develops new neurological signs

• Has difficulty urinating

• Appears painful despite medication

Breathing difficulty associated with chest lymphoma, intestinal obstruction, severe anaemia, treatment-related infection and neurological lymphoma can all become life-threatening before the next scheduled oncology visit.

What Should You Do Next?

1. Record the exact signs

Keep track of:

• Appetite

• Vomiting

• Stool quality

• Body weight

• Water intake

• Urination

• Breathing rate and effort

• Nasal discharge

• Activity

• Neurological changes

Patterns over several weeks are often more informative than one isolated bad day.

2. Arrange examination promptly

Do not dismiss chronic weight loss, recurring vomiting or progressive appetite change as normal ageing.

A stable cat can usually be assessed within the next few days. Breathing difficulty, repeated vomiting, collapse or neurological signs need faster care.

3. Obtain tissue whenever practical

Ask which sample is most likely to give a useful answer:

• Fine-needle aspirate

• Core biopsy

• Endoscopic biopsy

• Surgical biopsy

• Nasal biopsy

• Skin biopsy

• Cerebrospinal fluid

• Bone marrow

The least invasive test is not always the most useful test.

4. Ask for the exact diagnosis

Useful questions include:

• Where is the lymphoma located?

• Is it low-grade or high-grade?

• Are the cells small, intermediate or large?

• Is it T-cell or B-cell?

• Is the diagnosis based on cytology or histopathology?

• Were immunohistochemistry or PARR performed?

• Is the disease localised or systemic?

“Lymphoma” alone is not enough information for a meaningful prognosis.

5. Complete useful staging

Discuss which tests will genuinely change treatment.

These may include:

• FeLV and FIV testing

• Chest imaging

• Abdominal ultrasound

• CT

• MRI

• Lymph node sampling

• Liver or spleen sampling

• Bone marrow assessment

6. Discuss referral early

An internal medicine specialist, medical oncologist or radiation oncologist may help with:

• Difficult intestinal diagnosis

• Multiagent chemotherapy

• Nasal lymphoma

• Nervous-system lymphoma

• Radiation planning

• Rescue treatment

• Complicated relapse

Referral does not commit you to aggressive treatment. It provides clearer choices.

7. Decide on the goal

Treatment may aim to:

• Achieve remission

• Control disease for as long as possible

• Relieve an obstruction

• Restore appetite

• Improve breathing

• Maintain comfort

• Provide palliative care

The correct plan is the one that balances expected benefit with the cat’s welfare and the family’s practical limits.

8. Create a monitoring plan

Monitoring may include:

• Body weight

• Complete blood count

• Kidney and liver values

• Physical examination

• Ultrasound

• Chest imaging

• CT or MRI

• Clinical symptom logs

A cat that is losing weight despite improving scan results is not fully controlled.

Common Mistakes Owners Should Avoid

Assuming every lymphoma behaves the same way

Low-grade intestinal lymphoma and high-grade renal lymphoma are entirely different clinical diseases.

Diagnosing intestinal lymphoma from ultrasound alone

Ultrasound can identify suspicious changes but cannot reliably distinguish chronic inflammation from low-grade lymphoma.

Starting long-term treatment without obtaining a diagnosis

When the cat is stable, obtain the most useful samples before weeks of corticosteroid treatment alter the clinical picture.

Assuming a negative FeLV result rules lymphoma out

Most modern feline lymphoma cases are not FeLV antigen-positive.

Believing surgery alone treats systemic lymphoma

Surgery is useful for selected local complications and solitary disease. Most lymphoma requires medical or radiation treatment.

Waiting for an older cat to become visibly thin

Cats can lose substantial muscle before the change becomes obvious under their coat.

Ignoring appetite during chemotherapy

Reduced food intake is not merely an inconvenience. It can cause dehydration, muscle loss and hepatic lipidosis.

Comparing one survival statistic with another

Study populations differ in location, grade, stage and treatment. Published medians should guide discussion, not dictate a deadline.

Assuming chemotherapy will make a cat constantly sick

Most cats tolerate treatment well, and doses can be adjusted when adverse effects occur.

Can Feline Lymphoma Be Prevented?

Most cases cannot be reliably prevented.

Practical risk-reduction measures include:

• FeLV testing for new cats

• FeLV vaccination when appropriate for lifestyle and exposure risk

• Preventing contact with FeLV-positive cats

• Keeping cats indoors or using secure outdoor enclosures

• Investigating chronic weight loss, vomiting or diarrhoea

• Recording body weight during senior examinations

• Reassessing intestinal disease that stops responding normally

• Attending regular veterinary examinations

FeLV prevention has contributed to a reduction in virus-associated lymphoma, but it cannot prevent most modern feline lymphoma cases.

The most realistic opportunity is early recognition and accurate classification.

Frequently Asked Questions

Can lymphoma in cats be cured?

Some localised forms, particularly nasal lymphoma treated with radiation, may achieve very long-term control and possibly functional cure. Most systemic forms are considered manageable rather than permanently curable, although long remissions can occur.

How long can a cat live after a lymphoma diagnosis?

Survival may range from weeks to several years. Low-grade intestinal and localised nasal lymphoma generally have the longest outcomes, while large granular, advanced neurological and treatment-resistant high-grade lymphoma have poorer prognoses.

Is chemotherapy painful for cats?

Chemotherapy administration itself is not usually painful beyond placing an intravenous catheter when required. Most cats tolerate treatment well, although nausea, reduced appetite, diarrhoea and low blood-cell counts can occur.

Can ultrasound confirm lymphoma in a cat?

Sometimes ultrasound-guided aspiration of a mass can confirm high-grade lymphoma. Ultrasound appearance alone cannot confirm lymphoma and is particularly unreliable for distinguishing low-grade intestinal lymphoma from inflammatory bowel disease.

Is feline lymphoma contagious?

Lymphoma itself is not contagious. FeLV, which can increase lymphoma risk, can spread between cats. FeLV testing and risk-based vaccination remain important.

Final Takeaway

Lymphoma is one of the most variable cancers diagnosed in cats.

The term may describe a slow intestinal disease controlled with tablets for years, an aggressive abdominal mass requiring injectable chemotherapy, a chest tumour causing a breathing emergency or a local nasal tumour that responds extremely well to radiation.

The three most important questions are:

1. Where is the lymphoma?

2. Is it low-grade or high-grade?

3. What treatment goal is realistic for this cat?

Ultrasound and bloodwork can raise suspicion, but cytology or biopsy is usually needed to define the disease properly. Once the form has been identified, treatment and prognosis become far more meaningful.

Most importantly, do not wait for a cat to become profoundly thin, stop eating or struggle to breathe before seeking care. Earlier investigation gives the veterinary team more diagnostic options and gives the cat the greatest chance of a useful treatment response.

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If you are trying to understand your cat’s biopsy, ultrasound, chemotherapy options or whether new symptoms are urgent, ASK A VET™ can help you organise the results and prepare the right questions for your veterinarian.