For most pets, vaccination is effective in preventing future disease. Occasionally, a vaccinated pet may not develop adequate immunity and, although rare, it is possible for these pets to become ill if exposed to the disease. These gaps in protection should be as short as possible to provide optimal protection against disease for the first few months of life. It is important to remember that although breakdowns in protection do occur, most appropriately vaccinated pets are able to successfully fight off disease–reinforcing the importance of vaccines in your pet’s preventive health care program.