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Feline leukaemia virus

Want to know more about feline leukaemia virus (FeLV)? Find out about this common illness in our guide.

Feline leukaemia virus

Want to know more about feline leukaemia virus (FeLV)? Find out about this common illness in our guide.

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What is feline leukaemia virus (FeLV)?

FeLV is a virus that causes a fatal disease in cats by affecting the immune system, making them more vulnerable to other infections, anaemia or tumours. It does not infect humans.

How do cats catch FeLV?

The virus is usually spread through direct contact with the saliva of infected cats. This can occur through grooming or sharing food and water bowls or through mating behaviour. It can also be transmitted from an infected mother cat to her kittens while they are in the womb or through her milk. 

Following infection

After becoming infected with FeLV, some cats are able to clear the infection and recover after a few weeks. These cats often develop some immunity, making them less likely to be infected again. However, younger or weaker cats, as well as those with more exposure to the virus, are more likely to remain permanently infected. 

What are the signs of FeLV?

There is an incubation period of months or sometimes years before signs of infection show in those cats that are permanently infected. Sadly, around 80% of cats diagnosed with FeLV die within three to four years.

Many different signs can be seen, including:

  • recurrent infection, for example with respiratory infections, sore gums or digestive problems
  • seeming quieter than normal, off their food or having a high temperature
  • enlarged lymph nodes which will often be cancerous, for example internally or around the throat, armpit, groin or knee regions
  • severe anaemia 
  • taking a long time to recover from infections
  • development of cancers
  • breeding problems

FeLV testing

Vets can quickly perform a test to detect the virus in blood. It’s recommended that positive results, especially from otherwise healthy cats, are sent for confirmation at an external laboratory, as false positive results can occur. As some cats are able to clear the infection after a few weeks, it may also be a good idea to retest some weeks after a first positive test result. 

Results can be inaccurate if the cat has only recently been exposed to the virus. It is recommended that you wait before retesting negative cats if they are known to have had direct contact with other FeLV-positive cats. FeLV-negative cats should be kept separate from FeLV-positive cats during this period.

Treatment for FeLV

Unfortunately, there is currently no reliable treatment for FeLV so vets will treat each FeLV-positive cat individually, depending on the signs they develop. Sadly, the long-term outlook is likely to be poor.

Keeping infected cats indoors and ensuring they are fully vaccinated will help to protect them from other infections and prevent the spread of FeLV to other cats. Any secondary recurrent infections may be treated with antibiotics and/or anti-inflammatory drugs as necessary. 

Many affected cats have to be euthanased because they have a poor quality of life. It is Cats Protection policy to not rehome cats known to be infected with FeLV.

Cats Protection recommends that FeLV-positive cats are kept indoors and only allowed outside in a secure, impenetrable garden. They should not be allowed direct contact with FeLV-negative cats to avoid spread of this disease which is fatal in persistently infected cats.

Indoor cats

Protecting against FeLV

There is a vaccination available to protect cats against FeLV. Kittens and unvaccinated cats require an initial course of two injections three to four weeks apart and then boosters depending on their risk and lifestyle. The vaccination is not effective in cats that are already infected with FeLV, and protection cannot be guaranteed, so FeLV-positive cats should not mix with FeLV-negative cats. Since the introduction of vaccines and testing strategies, the number of FeLV cases in the cat population has significantly decreased. Cats whose infection or previous vaccination history is unknown can be tested before starting vaccinations. 

Vaccinations

My cat died from FeLV, can I get another cat?

The virus does not survive long in the environment, so it is safe to bring a new cat into the house soon after losing an FeLV-positive cat. It is a good idea to disinfect the food bowls and litter trays before using them again. If you already have other cats, it is advisable to wait and get them tested for the virus before introducing another cat. Speak to your vet for further advice.

Free guide

Download our free guide packed full of all the information you need about feline leukaemia virus (FeLV).

FIV and FeLV guide
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