Feline Leukaemia

Tortoiseshell and white cat with ginger and tortoiseshell kittensFeline leukaemia virus (FeLV) is a type of retrovirus which has the ability to cause cancer to develop, but can also lead to a poor immune response and a susceptibility to other infections. It is transmitted by direct contact with an infected cat, usually through mutual grooming but can also be transmitted through biting, and an infected queen will lead to infected kittens.

A cat can become infected with FeLV and have several different outcomes:

  • it may mount an effective immune response which attacks the virus and destroys it.  If this happens, the cat is then immune for life.
  • it may mount an effective immune response and contain the virus causing the virus to still be present in some parts of the body, but not to cause disease.
  • the virus may continue to multiply in the bone marrow causing a permanent infection which the body’s immune system can never destroy.  This leads to a permanent infection which is likely to lead to disease in the future.



Treatment for FeLV

Unfortunately, there is no cure for FeLV, the main treatment is in managing any secondary infections, maintaining general good health and hygiene, and protecting against other infectious disease.  Because FeLV is transmissible to other cats, infected cats should be kept isolated from non-infected cats.



Cats acting aggressively towards each otherPrevention of FeLV

There is a vaccination available against FeLV which is highly effective, however it will only be effective in cats which are not already FeLV positive.  Ideally, therefore, all cats should be tested (a simple blood test) prior to vaccination.  If you have an indoor-only cat who has no access to other cats, the FeLV risk is negligible so vaccination is not necessary.  However, if you have a multi-cat household, and/or a cat who goes outside a lot and mixes with other cats, vaccination is very important.

The initial vaccination course involves two injections around 3-5 weeks apart (this timing is important), followed by a booster vaccination after 1 year.  The WSAVA guidelines state that vaccinations after this should be given every 2-3 years in cats at risk of exposure.  In practice, however, most of the vaccines currently available in the UK require an annual re-vaccination on the data sheet so you may need to sign an ‘off-label consent‘ form if you wish to vaccinate less frequently than this.



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