For an i.n. product cats 12 weeks of age or older should be vaccinated with one dose. In the past it has been recommended that annual revaccinations with a single dose be given. Just because a vaccine is only required every 3 years does not mean that a cat does not need to see a veterinarian on a yearly basis. Annual physical exams are important for the general health and well-being of any animal. The clinical signs depend on the virulence of the particular subtype and the route of infection.
Persistent carriers are common and continue the cycle of infection in the population.
Infection can be prevented by minimizing overcrowding, stress, and exposure, as well as vaccinating. Precautions need to be taken in multi-cat environments when an animal becomes infected. Follow guidelines and make sure your cat sees a veterinarian on a regular basis to ensure their continued health. Castro, A.E. and W.P. Heuschele. Veterinary Diagnostic Virology-A Practitioner s Guide.