In recent years, the vaccination of cats has become more popular. The three most common vaccines give protection against feline infectious enteritis (FIE), feline influenza (cat flu) and feline leukaemia (FeLV). An initial course of two injections, the first at nine weeks are usually given, and yearly boosters are recommended thereafter.

FIE causes vomiting and diarrhoea, and the cat develops a very high temperature. Before the vaccine was introduced, it killed a great many cats by dehydration due to the bowel symptoms. Cat flu is caused by two viruses: the feline rhinotracheitis (FCV). FVR is the more severe of the two, causing coughing, sneezing, and nasal and eye discharges.

FVC has milder discharges but more gum inflammation and mouth ulcers. Neither FCV nor FVR is usually deadly but the infection can linger on in the form of snuffles, and some cats become symptomless carriers of the disease. When stressed, these cats develop mild symptoms and spread the virus.

FeLV suppresses the activity of the cat's immune system, allowing a wide range of symptoms to develop. It often results in the death of the cat after several months of illness. The virus is spread mainly in the cat's saliva. It is a disease of cats that fight a lot, and of cats in large colonies, who share the same food and water bowls. It should not be a threat in a well-run boarding cattery, where the feeding and grooming utensils are properly cleaned, and the cats do not mix with each other.

A vaccine exists against the chlamydial organism, which can cause not only mild eye and nasal symptoms, but more importantly, infertility and abortion. This vaccine is used mainly in breeding colonies to protect against infertility.