Historically, annual vaccination had been recommended. There were two reasons. The most important was that vaccine manufacturers had proof that the core vaccines provided immunity for at least a year.
The second reason used to justify annual vaccination was that pets benefit from an annual health check – usually given at the time of vaccination. This check facilitates the early detection of heart disease, renal disease and tumours and is an ideal opportunity to remind owners about parasite control, discuss management of skin disease, neutering and the like.
There are challenge studies showing that some canine and feline core vaccines can protect the majority of vaccinated animals for 3 years. The efficacy of vaccines is likely to differ between manufacturers.
What is also stressed again and again is that there cannot be a universally applicable vaccination policy. Rather, the protocol should be adapted for each particular individual’s situation.