The first rabies vaccination given to a dog at around four to six months of age lasts for one year, at which time the dog requires a booster rabies vaccination. The second round of rabies vaccinations and all subsequent vaccinations last for three years.
Regardless of how long the vaccination is meant to be effective, a number of factors can reduce the length of time that a rabies vaccination is effective in any given dog. Factors that can affect the vaccine's effectiveness include the dog's overall health, the health of its immune system, and the strength of the rabies virus that is given to the dog.
