Feline Leukaemia Virus (FeLV) is the biggest killer of cats in the UK apart from after car accidents. Infected animals may not show any signs for months or even years, so many more cats may be infected before the warning signs are seen.
It is easily spread in saliva and blood, so cats are infected when grooming each other, sharing food bowls and litter trays and when fighting.
Animals are usually infected in the first months of life, but any age of animal including adults and unborn kittens may become infected.
FeLV attacks the white blood cells and bone marrow. This makes the cat vulnerable to secondary infections. It also causes anaemia and cancer of the blood, intestines and other parts of the body.
One in three cats that catch the virus will develop the disease. Only early vaccination and regular boosters can protect your cat from the virus.