In general, horses will get vaccinations every year. Typically, shots are administered in spring, as this provides the best protection for mosquito-borne illnesses.
According to the AAEP, core vaccination for horses consist of rabies, Eastern and Western equine encephalomyelitis (EEE/WEE), tetanus, and West Nile Virus.
Some of the most common risk-based vaccines include Equine Influenza, Strangles, Equines Herpesvirus (Rhinopneumonitis), Potomac Horse Fever, and Botulism.
It is important to keep your horse safe from preventable diseases by vaccinating them annually. All horses should receive core vaccines, though many will also receive risk-based vaccines as well.