There are a number of infectious diseases for which we have no effective cure or treatments. Vaccines are available for some of these diseases. This gives us the opportunity to prevent our animals contracting these diseases in the first place.
Booster vaccinations are necessary at scheduled intervals as one vaccination will not provide lifelong protection. Also the length of time of vaccine protection varies between individual animals; to ensure continued protection the animal should receive booster vaccinations at the scheduled intervals.
All the diseases for which we have vaccines occur every year in different parts of the country. Many animals are protected by vaccinations so these diseases cannot spread. However if we did stop vaccination any of these diseases would become widespread again.