Strepvax II is an equine vaccine that protects against strangles caused by Strep equi. This strangles vaccine is made with concentrated M-protein extract to provide protection with the minimum amount of side effects. Dosage is three 1 ml doses given at 3-week intervals initially, with an annual booster thereafter. Foals less than 3 months should receive an additional dose at 6 months or at the time of weaning. Consult with your veterinarian about the advisability of vaccinating for strangles.