5, 7, and 9 months of pregnancy using an inactivated EHV-1 vaccine licensed for prevention of abortion; some veterinarians recommend also vaccinating at 3 months of pregnancy
Botulism
4 to 6 weeks before foaling in geographic regions where botulism causes disease
Equine viral arteritis (EVA)
Serology to check for antiviral antibodies should be done before vaccination; pregnant mares should not be vaccinated; if serology is negative, mares should be vaccinated before breeding to a positive stallion that is shedding the virus; mares must be isolated from other horses for 3 weeks after initial vaccination; positive titers may cause problems if the mare is to be shipped internationally
Rotaviral diarrhea
8, 9, 10 months of pregnancy; for all mares, regardless of vaccination history, in high-volume breeding programs
