All adult horses should receive annual boosters after the initial foal series. Foals should be vaccinated at three and four months of age, and then annually. Broodmares should be vaccinated one month prior to foaling. This provides high levels of tetanus antibody in the colostrum for the newborn foal. Any horse suffering an open would should have its tetanus immunization record reviewed and receive a booster if necessary.
Tetanus can be a very deadly disease.
With proper vaccination and good farm management, however, no horse should suffer from tetanus.