Horse Vaccination Schedule: Core & Risk-Based Vaccines by Age (2026 Guide)

By Brian Bickell, who raises paint and quarter horses at Bickell Ranches in Stillwater, Oklahoma.

A vaccination schedule should be one of the simplest things in horse ownership. Four core vaccines, a few risk-based ones depending on where you live and what you do, and annual boosters.

But it's not simple, because schedules vary by age, risk, geography, and competition requirements. And because a missed booster doesn't just mean "give it late." For some vaccines, a lapsed schedule means starting the entire primary series over from scratch.

The good news: once you understand the framework, it's manageable. The key is having a system that tracks vaccination dates, sends reminders when boosters are due, and stores the details your vet and show secretary need.

Here's what your horse needs and when.

Educational, not veterinary advice. The schedules here summarize AAEP guidelines so you know what to ask about. Actual vaccine selection, timing, and wound-protocol decisions belong to your veterinarian, who knows your horse, your region, and the current disease picture.

In This Guide

• The Four Core Vaccines
• Risk-Based Vaccines
• Foal Vaccination Schedule
• What to Record for Every Vaccination
• Deworming: The Modern Approach
• Common Mistakes

The Four Core Vaccines

The AAEP (American Association of Equine Practitioners) designates four vaccines as core, meaning every horse needs them, regardless of age, breed, use, or location.

Tetanus

• Primary series: 2 doses, 4–6 weeks apart
• Booster: Annually
• Wound protocol: After a puncture wound, call your vet. Standard practice: boost if it's been more than 6 months since the last tetanus shot, or give both antitoxin and toxoid at separate sites if history is unknown. Your vet makes the call.

Tetanus is caused by Clostridium tetani, which lives in soil everywhere, especially around livestock. The disease is nearly 100% fatal without treatment. This is the one vaccine you absolutely cannot skip.

Eastern/Western Equine Encephalomyelitis (EEE/WEE)

• Primary series: 2 doses, 4–6 weeks apart
• Booster: Annually in spring, before mosquito season
• Gulf Coast/tropical regions: Boost semi-annually (spring and fall) due to year-round mosquito activity

EEE has a mortality rate of 75–90% in unvaccinated horses. WEE is lower at 20–50%, but still devastating. Both are mosquito-borne, so timing matters. You want peak immunity to align with peak mosquito season. In most of the U.S., that means vaccinating by April or May.

West Nile Virus

• Primary series: 2 doses, 3–6 weeks apart (killed vaccine); check the label for recombinant products, as some may differ
• Booster: Annually before mosquito season; semi-annually in endemic areas

West Nile kills about a third of unvaccinated horses that develop clinical disease. Like EEE/WEE, it's mosquito-borne and follows the same seasonal timing.

Rabies

• Primary series: Single dose at 12 months of age or older
• Booster: Annually
• Note: Must be administered by a licensed veterinarian in most states

Rabies is 100% fatal once clinical signs appear. Some states mandate rabies vaccination for all livestock. Even where it's not legally required, the AAEP considers it core because of the zoonotic risk — an unvaccinated horse with rabies becomes a public health emergency.

Risk-Based Vaccines

These are recommended based on your horse's exposure risk: geography, travel, contact with other horses, and reproductive status.

Equine Influenza

• Primary series: 3 doses — initial, 4–6 weeks later, then 6 months after the second
• Booster: Every 6 months for horses that travel or show; annually for low-risk horses
• Competition requirement: USEF requires influenza vaccination within 6 months. FEI requires it within 6 months + 21 days, but not within 7 days before competing.

If your horse goes to shows, trail rides, or any facility with horse turnover, influenza vaccination is essentially mandatory. See our horse show document checklist for the full list of what you need at competition.

Equine Herpesvirus / Rhinopneumonitis (EHV-1/EHV-4)

• Primary series: 2 doses, 4–6 weeks apart
• Booster: Every 6 months for at-risk horses
• Pregnant mares: Killed vaccine at months 3, 5, 7, and 9 of gestation (Pneumabort-K or equivalent). See our foaling records guide for the full pregnant mare management timeline.
• Competition requirement: USEF requires EHV vaccination within 6 months

EHV-1 can cause respiratory disease, abortion, and the neurological form (EHM) that triggers show shutdowns. Current vaccines reduce respiratory and abortion risk but do not reliably prevent EHM. Vaccinate anyway. Reduced shedding still helps.

Strangles

• Intranasal (preferred): Single dose, booster annually
• Intramuscular: 3-dose series, 2–3 weeks apart

Strangles is common and highly contagious, but the vaccine is controversial. Talk to your vet before vaccinating — the standard guidance is to avoid it in horses currently exposed to or recently recovered from strangles (it can worsen the disease), to never give the intranasal product intramuscularly (severe abscess risk), and to consider pre-vaccination titer testing.

Potomac Horse Fever

• Who needs it: Horses in the eastern U.S., Pacific Northwest, Great Lakes, or near waterways
• Primary series: 2 doses, 3–4 weeks apart
• Booster: Semi-annually in endemic areas, timed for late spring and late summer

Botulism

• Who needs it: Mid-Atlantic states (Kentucky, Maryland, Virginia, West Virginia, Pennsylvania) — "Shaker Foal Syndrome" areas
• Primary series: 3 doses, 4 weeks apart
• Booster: Annually
• Broodmares: Booster 4–6 weeks before foaling for colostral antibody transfer

Other Risk-Based Vaccines

• Equine Viral Arteritis (EVA): Primarily breeding stallions. Requires pre-vaccination serology — never vaccinate a seropositive stallion without veterinary guidance.
• Rotavirus: Broodmares only, 3 doses at months 8, 9, and 10 of gestation to protect foals via colostrum.

Foal Vaccination Schedule

Foals present a timing challenge: maternal antibodies from colostrum interfere with vaccines until they decline at 4–6 months.

If the mare was properly vaccinated:

Age	Vaccines
4–6 months	Begin core vaccines (tetanus, EEE/WEE, WNV) — 3-dose primary series, each 4–6 weeks apart
6 months	First rabies dose; begin influenza/EHV if needed
12 months	Rabies booster; boosters for all primary series

If the mare's vaccination history is unknown: Start core vaccines at 3–4 months to compensate for potentially inadequate colostral protection.

In botulism-endemic areas with unvaccinated dams: Foal series at 2, 3, and 4 weeks of age.

For more on foal health monitoring — including IgG testing, meconium passage, and neonatal milestones — see our foaling records guide.

What to Record for Every Vaccination

This is where most horse owners fall short. Getting the vaccine is the easy part. Recording the right details is what makes the record actually useful later.

For every vaccination, document:

1. Date administered
2. Product name (e.g., "Fluvac Innovator 5," not just "flu shot")
3. Manufacturer (Zoetis, Boehringer Ingelheim, Merck)
4. Lot/batch number — critical for adverse event reporting and recall tracking
5. Route (intramuscular, intranasal, subcutaneous)
6. Injection site (left neck, right pectoral, etc.) — rotate sites between visits
7. Administering veterinarian
8. Any adverse reactions (swelling, fever, lethargy — note onset time and duration)
9. Next due date

The lot number is the one most people skip, and it's the one that matters most when things go wrong. If your horse has an adverse reaction, the USDA Center for Veterinary Biologics needs the lot number to investigate. Without it, they can't link the reaction to a specific production batch or issue a recall.

Tip: In HorseBook, you can scan the vaccine sticker your vet leaves behind — the one with the product name, lot number, and expiration date — and it's filed with that horse's medical record. No typing, no forgetting to write down the lot number while the vet is still talking.

For a broader look at all the veterinary records you should be keeping (not just vaccinations), see our equine veterinary records guide.

Deworming: The Modern Approach

If you're still deworming every horse on a rotating calendar every 8 weeks, that approach is about 15 years out of date. The AAEP now recommends fecal egg count (FEC)-based targeted deworming.

How It Works

Your vet runs a fecal egg count to classify each horse:

• Low shedder (under 200 EPG): Treat 1–2 times per year
• Moderate shedder (200–500 EPG): Treat 2–3 times per year
• High shedder (over 500 EPG): Treat 3–4 times per year

About 50% of horses are low shedders — they're getting unnecessary treatments under the old calendar system, which accelerates drug resistance across the whole herd.

A Practical Framework

• Spring (March–April): Run fecal egg counts on all horses. Treat based on results. Include praziquantel for tapeworms.
• Mid-season: Additional treatments for moderate and high shedders based on follow-up FEC.
• Late fall/early winter (after first hard frost): Ivermectin or moxidectin to target bots and encysted small strongyles. Include praziquantel.

Verify your dewormers still work. Run a fecal egg count reduction test (FECRT) 10–14 days after treatment. If the egg count doesn't drop by at least 90%, you have resistance, and treating with a drug that doesn't work is worse than not treating at all, because it selects for resistant parasites.

Common Mistakes

Missing a booster in a primary series. The first dose of most vaccines only primes the immune system — it's the second (and sometimes third) dose that builds protection. Skip or delay the booster by too long and you may need to restart the entire series.

Vaccinating a sick or stressed horse. The immune response is compromised. Move the appointment. Live vaccines (intranasal strangles) can actually cause clinical disease in a compromised horse.

Not tracking injection sites. If three vaccines go into the same spot and your horse develops a swelling, you can't tell which one caused it. Rotate sites and record them.

Ignoring regional risks. Skipping Potomac Horse Fever in an endemic area or botulism in the mid-Atlantic is rolling the dice on diseases that are preventable.

The Bottom Line

Vaccination is one of the few things in horse ownership where spending a little money now reliably prevents spending a lot of money (and heartbreak) later.

The schedule itself isn't that complicated once it's written down. The hard part is staying on top of boosters, recording the right details, and adjusting for your horse's specific risk factors. A vaccination record that says "flu shot, March" isn't useful. One that says "Fluvac Innovator 5, Zoetis, lot #12345, left neck IM, Dr. Smith, March 15 — due September 15" is.

Keep the records where you can find them, set reminders for upcoming boosters, and talk to your vet about which risk-based vaccines make sense for your situation. HorseBook handles the tracking and reminders — but whatever system you use, the principle is the same. Record it once, record it right.

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Brian Bickell is the founder of HorseBook and raises paint and quarter horses at Bickell Ranches in Stillwater, Oklahoma.