February Newsletter: When Should Horses Be Vaccinated?

Three horses eagerly await their vaccinations.

When Should Your Horse Be Vaccinated?

Keeping up with a recommended vaccination schedule is an easy way to ensure that your horse is protected from rabies, West Nile Virus, and other serious illnesses. Not sure when to vaccinate your horse? Read on for the latest information.

Foal Vaccination Schedule (for Foals Less Than 12 Months)

Foals receive immune system antibodies in colostrum, the nutrient-rich first milk produced by the mare after giving birth. Unfortunately, this immune system boost generally wears off by the time the foal is a few months old, according to the Cornell University College of Veterinary Medicine. Following a core vaccine schedule recommended by your veterinarian will help keep your foals healthy. Many vaccine schedules for horses include:

  • Eastern Equine Encephalitis (EEE) and Western Equine Encephalitis (WEE). The American Association of Equine Practitioners (AAEP)recommends three doses of the vaccine for foals. The first dose should be given at 4 to 6 months, the second 4 to 6 weeks later, and the third at 10 to 12 months. This schedule applies to foals born to vaccinated and unvaccinated mares. Horses need annual EEE/WEE vaccinations after completing this series.
  • Rabies. If the mare is vaccinated against rabies, foals will need rabies vaccines at 4 to 6 months and an additional dose 4 to 6 weeks later. If the mare is unvaccinated, the foal should receive one dose at 4 to 6 months. The AAEP notes that foals born to vaccinated mares need two dosages to account for potential maternal antibody interference. Annual vaccinations are needed every year thereafter.
  • Tetanus. Foals born to unvaccinated mares should receive the first dose of the tetanus vaccine at 3 to 4 months, while foals born to vaccinated mares should receive the first dose at 4 to 6 months. Both groups should receive a second dose 4 to 6 weeks after the first dose, followed by a third dose at 10 to 12 months. Annual tetanus vaccines after the foal series will protect your horse from this fatal disease.
  • West Nile Virus. All foals need three doses of the West Nile Virus vaccine given at 4 to 6 months, 4 to 6 weeks after the first dose, and 10 to 12 months. Revaccination is recommended every year.

Adult Horse Vaccination Schedule

Adult horses should follow this schedule provided by the AAEP:

  • EEE/WEE. Previously vaccinated horses should receive annual EEE/WEE vaccines. If an adult horse is unvaccinated against EEE/WEE, it will need one dose, followed by the second dose 4 to 6 weeks later before starting an annual vaccination schedule.
  • Rabies. Adult horses need rabies vaccines every year.
  • Tetanus. Previously vaccinated horses need annual tetanus vaccines. Adult horses that haven't received a previous tetanus vaccine will need one vaccine dose, followed by a second dose 4 to 6 weeks later.
  • West Nile Virus. Annual vaccination is needed for previously vaccinated horses. Unvaccinated horses receive one dose followed by a second dose 4 to 6 weeks later.

Broodmares follow slightly different vaccination schedules. Vaccinating your mare before foaling offers a simple way to protect the foal from illnesses before it's old enough to receive vaccines.

Risk-Based Vaccines

Your foal or adult horse may need other vaccines depending on its risk factors. For example, a horse that travels to shows or events may require equine influenza and equine herpesvirus vaccines. Your horse might also need a risk-based vaccine if a disease or virus is present in your area. Your equine veterinarian may recommend one or more of these vaccines based on your horse's risk factors.

Risk-based vaccines protect against:

  • Anthrax
  • Botulism
  • Equine Herpesvirus
  • Equine Influenza
  • Equine Viral Arteritis
  • Leptospirosis
  • Potomac Horse Fever
  • Rotavirus
  • Snake Bite

Is your adult horse or foal due for its vaccinations? Call our office to schedule a visit with the equine veterinarian.


Cornell University College of Veterinary Medicine: Discovering the Early-Age Immune Response in Foals, 6/26/2017


American Association of Equine Practitioners: Foal Vaccination Chart


American Association of Equine Practitioners: Adult Horse Vaccination Chart


Penn State Extension: Risk-based Vaccines: Does Your Horse Need Them?, 4/9/2021


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