For pregnant mares, aseptically administer one 2 mL dose intramuscularly during the 5th, 7th and 9th months of pregnancy. Revaccinate annually at the 5th, 7th and 9th months of pregnancy.
For young horses, aseptically administer one 2 mL dose intramuscularly after weaning, followed by a second 2 mL dose 3 to 4 weeks later. Revaccinate with a single 2 mL dose 6 months after the second primary dose and annually thereafter. To insure proper placement and retention of the vaccine, inject deep into the heavy muscles of the hindquarter. Mild exercise to promote absorption is recommended for one week after injection.
Horses with a history of EHV infection and disease, including neurological disease, are likely to have immunity consequent to the infection that can be expected to last for 3 to 6 months or longer in older horses. Booster vaccination can be resumed 6 months after the disease occurrence.