Feline leukaemia virus in cats – signs and treatment

Updated 2026-09-30 · 2 sources

Based on: PDSA, International Cat Care (iCatCare)

Book a vet visit

Book a vet appointment if you think your cat has this – a vet needs to confirm it and plan the treatment. Feline leukaemia virus is a viral infection affecting cats.

What to do now

What you can do now

Contact your vet.
Note when it started, how often it happens and what else you see.
Take a photo or short video to show the vet.
Keep fresh water available.

Don't

Do not give any human medicine.
Do not wait if it gets worse.

What it is

Feline leukaemia virus is a viral infection affecting cats worldwide.^[2] It damages the immune system, increasing the risk of other illnesses, and can cause cancers such as lymphoma and leukaemia.^[1]

Signs

High temperature
Lethargy or tiredness
Eating less than normal
Weight loss
Persistent or recurrent breathing, skin and intestinal problems
Pale gums
Diarrhoea
Vomiting
Poor coat condition
Pregnancy loss and infertility

Causes and risk factors

Mutual grooming
Sharing food and water bowls
Sharing a litter tray, including contact with urine and faeces
Sexual contact
Biting
Kittens catching FeLV in the womb before they are born

How a vet finds out

Blood tests

How vets treat it

Diet change
Antiparasitic treatment
Chemotherapy
Blood transfusion

What the experts say

“Mutual grooming ; Sharing food and water bowls ; Sharing a litter tray (contact with urine and faeces) ; Sexual contact ; Biting ; Kittens can catch FeLV in the womb before they are born”
— PDSA [1]

“Feline leukaemia virus (FeLV) is a viral infection affecting cats worldwide. A cat permanently infected with FeLV is highly likely to develop disease related to the virus, which can cause suffering and death in cats.”
— International Cat Care (iCatCare) [2]

If your pet is struggling to breathe, has collapsed, is having a seizure or can't stand up: go to the nearest vet now.

Not sure how serious it is?

OkPaw asks a few quick questions about your pet and tells you in 30 seconds whether it can wait. Free on Google Play for Android.

OkPaw is on Android now – an iPhone version is on its way.

Common questions

What is feline leukaemia virus?

FeLV is a viral infection affecting cats.^[2]

How do vets diagnose FeLV?

Most vets use simple blood tests to diagnose FeLV.^[2]

Is there a cure for FeLV?

There is no cure for FeLV, and management is largely aimed at supporting your cat and treating any signs.^[2]

Sources

How this page was made: written with the help of AI from the sources below, then checked claim by claim against those sources. Urgency levels follow OkPaw’s fixed safety rules. It is guidance, not a diagnosis. How we write our pages