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Feline lymphoma
Lymphoma is the most common cancer in cats. It is born from lymphocytes, cells of the defense system present everywhere in the body. It can therefore settle almost anywhere: most often in the intestine, but also in the thorax, lymph nodes,...
What is it?
Lymphoma is the most common cancer in cats. It is born from lymphocytes, cells of the defense system present everywhere in the body.
It can therefore settle almost anywhere: most often in the intestine, but also in the thorax, lymph nodes, kidneys, nose or nervous system.
Its signs are discreet and long confused with simple aging. It is also one of the cat cancers that responds best to treatment.
Commonly observed signs
These signs are neither exhaustive nor specific. Only a veterinarian can establish a diagnosis.
Related signs — each one links to its page:
The signs depend on the organ affected and often appear gradually.
Intestinal form, the most common: slow weight loss, appetite which decreases or on the contrary remains, repeated vomiting, chronic diarrhea, sometimes a perceptible mass in the stomach.
Thoracic form: rapid then difficult breathing, hunched back, cat refusing to lie down — more common in young cats.
Lymph node form: swollen and firm lymph nodes under the jaw, in front of the shoulders or behind the knees.
Renal form: the cat drinks and urinates more, loses weight, vomits.
Nasal form: sneezing, discharge from one nostril, nosebleed, facial distortion.
Nervous form: abnormal gait, weakness of a train, convulsions.
In all forms: depression, dull hair, weight loss.
When to consult without delay
This list does not replace veterinary advice. It gathers situations that justify a prompt consultation.
Causes and risk factors
Lymphoma results from the uncontrolled multiplication of lymphocytes that have become abnormal.
Two feline viruses play a demonstrated role: feline leukosis virus (FeLV) and feline immunodeficiency virus (FIV), which significantly increase the risk.
Since the generalization of screening and vaccination against leukosis, the forms linked to FeLV have declined and the intestinal forms of older cats have become the most common.
Chronic inflammation of the intestine is suspected of promoting certain digestive forms.
Regular exposure to tobacco smoke in the home is an identified environmental factor.
Infection with feline leukosis virus or feline immunodeficiency virus.
Outdoor life without vaccination or screening, fights with other cats.
Age: digestive forms mainly affect older cats; thoracic and lymph node forms are more common in young cats infected with a virus.
Chronic intestinal inflammation that has been going on for a long time.
Smoking in the home.
Certain oriental lines, notably the Siamese, seem more concerned with the forms of the young cat.
Transmission
Lymphoma itself is not contagious: it is not transmitted to other cats or to humans.
On the other hand, the viruses that promote it, FeLV and FIV, are transmitted between cats — through saliva, bites, prolonged contact, or from mother to kittens. A diagnosed cat must therefore be tested for these viruses, in its own interest and that of other cats in the household.
Diagnosis and care
Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.
The veterinarian begins with a complete examination: weighing, palpation of the stomach and lymph nodes, listening to the thorax.
A blood test and urine analysis evaluate the general condition, kidneys, liver and look for anemia.
The FeLV and FIV test is part of the assessment of any suspicious cat.
Ultrasound of the abdomen identifies thickening of the intestinal wall, enlarged lymph nodes or organ damage; X-rays or a CT scan explore the thorax and nasal area.
The diagnosis is not made on imaging alone: cells or a tissue fragment must be taken, using a fine needle or biopsy, for laboratory analysis.
This analysis specifies the type of lymphoma – certain slowly evolving digestive forms are treated very differently from aggressive forms – which completely changes decisions.
Treatment
Lymphoma is a cancer that can be treated: chemotherapy is the standard treatment.
In cats, it is generally well tolerated: side effects exist but remain moderate in most animals, and hair loss is not the rule as in humans. The stated objective is quality of life, not cure at all costs.
The protocols combine several families of medications, administered in the office or at home depending on the case, with regular blood checks.
Some slowly developing digestive forms are controlled with lighter oral treatment, often for long periods.
Surgery has its place when a single mass blocks the intestine; radiotherapy is mainly aimed at nasal forms, where it is available.
Comfort care is as important as cancer treatment: anti-nausea medications, appetite stimulants, painkillers, nutritional support.
If cancer treatment is not an option, good quality palliative care often provides several months of comfort.
All these choices are discussed with the veterinarian, depending on the type of lymphoma, the cat's condition and what the family can assume. None of these decisions are bad if they put the pet's comfort first.
Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.
Prevention
Have any new cat tested for FeLV and FIV before introducing it into a home.
Vaccinate against feline leukosis cats that go out or live with conspecifics of unknown status: this is the most effective prevention lever.
Sterilizing limits fights and wandering, therefore the transmission of viruses.
Do not smoke inside the accommodation.
In older cats, regular weighing and an annual blood test can identify beginning weight loss, often the very first sign.
Vaccination
There is no vaccine for lymphoma itself.
On the other hand, vaccination against feline leukosis protects against a virus which greatly increases the risk of lymphoma. It is recommended for cats with access to the outdoors or living with other cats, after a preliminary test: it is not useful to vaccinate a cat that is already infected.
The veterinarian determines the protocol and the rhythm of the boosters according to the cat's lifestyle.
Possible complications
Obstruction or perforation of the intestine by a mass.
Accumulation of fluid in the chest, hindering breathing.
Anemia, sometimes severe, linked to the disease or treatment.
Reduced immune defenses and associated infections.
Marked weight loss and muscle wasting.
Kidney damage in renal forms, with renal failure.
Relapse after a period of remission: it is common and is part of the expected development.
When to see a veterinarian
Your cat is losing weight for no reason, even though she is still eating.
He has been vomiting or having diarrhea for more than a few days, or repeatedly for weeks.
You feel a mass in his stomach or swollen lymph nodes under his jaw or in front of his shoulders.
He is breathing quickly or with difficulty: emergency.
He sneezes on one side, has a nosebleed or his face becomes distorted.
He is depressed, his hair is dull and he is hiding: these are often the only signs in cats.
Prognosis
The prognosis depends a lot on the type of lymphoma and its location.
Slowly progressive digestive forms are often controlled for a long time with well-tolerated treatment.
Aggressive forms frequently respond to chemotherapy, with good quality remissions during which the cat returns to normal life, but relapses are expected.
A cat infected with FeLV, very thin or whose general condition is already altered at the time of diagnosis responds less well.
The objective of treatment in cats is comfort and time saved in good conditions, rather than healing.
Frequently asked questions
Will chemotherapy hurt my cat?
Feline protocols are designed to preserve quality of life. Most cats tolerate it well and continue to eat, play and sleep normally. Side effects — decreased appetite, vomiting, temporary fatigue — occur in some animals and can be treated. The treatment is adjusted or stopped if it weighs too much on the cat.
Is my lymphoma contagious to my other cat?
Cancer is not transmitted. But the viruses that favor it, FeLV and FIV, are transmitted between cats: have the other cats in the household tested and vaccinate those who can be vaccinated.
Can I get this disease from my cat?
No. Neither lymphoma, FeLV, nor FIV are transmitted to humans. These viruses are strictly feline.
What if I choose not to treat?
It is a legitimate choice, which has nothing to do with abandoning it. Comfort care — painkillers, anti-nausea medications, appetite support — often provide a good quality period. The veterinarian will help you spot when suffering takes over.
References
AAFP — American Association of Feline Practitioners
Content reviewed by the TunisieVet editorial team · Updated 09 August 2026
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