📋 At a Glance
⚠️ Vaccination Precautions — Do Not Vaccinate If
- The horse has a fever or is systemically ill — delay until recovered; vaccinating a sick horse is contraindicated
- The horse is pregnant and the vaccine is a modified live product — discuss all vaccination with your vet before administering to pregnant mares
- A severe reaction occurred to a prior vaccine — report to your veterinarian; a different product or pre-treatment protocol may be indicated
- Using the modified live intranasal Strangles vaccine — serious handling precautions apply; accidental self-inoculation is dangerous
- Watch for systemic reactions for 30 minutes after vaccination: hives, swelling, difficulty breathing — have epinephrine available or remain near the horse
AAEP Core Vaccines — What Every Horse Needs
The American Association of Equine Practitioners (AAEP) publishes vaccination guidelines that define core vaccines as those recommended for every horse in North America, regardless of geographic location or use. Core vaccine recommendations are based on the severity of the disease, the transmissibility of the pathogen, and the efficacy of available vaccines.
Core vaccines protect against diseases with significant morbidity and mortality where vaccination is consistently effective at reducing disease burden. They are not optional recommendations for horses at risk — they are baseline healthcare for all horses.
| Vaccine | Disease | Transmission | Recommended Schedule | Notes |
|---|---|---|---|---|
| EEE/WEE | Eastern & Western Equine Encephalomyelitis | Mosquito-borne arboviral infection; high fatality rate (75–90% for EEE) | Annually in spring before mosquito season; semi-annually in endemic regions or year-round warm climates | Often combined with Tetanus and West Nile in single product |
| Tetanus | Clostridium tetani neurotoxin from wound contamination | Not contagious — spores in soil enter through wounds | Annually; booster at time of any significant wound or surgery | Horses are highly susceptible to tetanus; no other species needs it more |
| West Nile Virus | Flavivirus causing neurological disease | Mosquito-borne (Culex species as primary vector) | Annually in spring; semi-annually in high-risk or year-round mosquito areas | First approved 2001; significant reduction in equine WNV mortality since widespread use |
| Rabies | Lyssavirus; fatal neurological disease | Bite wound from infected mammal (skunks, raccoons, foxes, bats in most regions) | Annually | Also a human public health concern; zoonotic; required in some states |
Risk-Based Vaccines — Tailored to Your Horse's Exposure
Risk-based vaccines are recommended based on individual horse factors: geographic region, proximity to other horses, competition and travel schedule, boarding environment, and specific disease prevalence in your area. Your veterinarian determines which risk-based vaccines are appropriate for your horse's situation.
| Vaccine | Disease | Who Should Consider | Frequency | Key Notes |
|---|---|---|---|---|
| Equine Influenza | Respiratory virus — highly contagious aerosol spread | All horses with event, clinic, trail, or boarding exposure | Every 6 months for show/performance horses; annually for low-exposure horses | AAEP recommends 6-month boosters for horses with significant exposure |
| EHV-1/4 | Equine Herpesvirus — respiratory, abortive, neurological (EHM) forms | Show horses, broodmares, horses at facilities with new horse intake | Every 6 months for performance; months 5/7/9 of pregnancy for mares | Does not protect against EHM reliably — biosecurity remains essential |
| Strangles | Streptococcus equi — lymph node abscessation | Horses with frequent exposure to unknown horses; endemic area facilities | Annually; discuss timing with your vet | MLV intranasal and killed IM products available; do not vaccinate horses with high S. equi titers — purpura risk |
| Potomac Horse Fever | Neorickettsia risticii — diarrhea and laminitis | Horses in river valley endemic areas (mid-Atlantic, Pacific Northwest) | Annually; spring before fly season | Geographic vaccine — discuss with your vet whether relevant to your region |
| Botulism | Clostridium botulinum — toxin causes flaccid paralysis | Foals (Shaker Foal syndrome); horses in hay fermentation risk areas; Round bale users | Primary series + annual booster | Particularly important in Kentucky and eastern states; foal protection via immunized mares |
| EVA | Equine Viral Arteritis — respiratory and reproductive disease | Breeding stallions before the season | Annually for breeding stallions; mares per breeding program requirements | Regulatory requirements vary by state; some stallions have natural titer |
Vaccination Schedules by Horse Type
Different horses in the same barn may appropriately receive different vaccination protocols based on their use and exposure risk. The following provides educational context for the conversations worth having with your veterinarian.
| Horse Type | Core Vaccines | Recommended Risk-Based | Notes |
|---|---|---|---|
| Adult pleasure horse, home only | EEE/WEE, Tetanus, WNV, Rabies — annually | Influenza annually; EHV if horses visit or arrive | Lowest risk profile; core vaccines are the priority |
| Show/competition horse | EEE/WEE, Tetanus, WNV, Rabies — annually | Influenza every 6 months; EHV every 6 months; Strangles based on facility | High exposure profile; some competitions require proof of current vaccination |
| Breeding stallion | EEE/WEE, Tetanus, WNV, Rabies — annually | Influenza; EHV; EVA before season; Botulism in endemic areas | Breeding stallions may have legal testing requirements by state |
| Pregnant mare | EEE/WEE, Tetanus, WNV, Rabies — 4–6 weeks pre-foaling | EHV-1 at months 5, 7, and 9; Influenza; Botulism | NO modified live vaccines during pregnancy; timing matters for colostrum antibody transfer |
| Foal (dam vaccinated) | Begin primary series at 4–6 months | Match dam's risk profile; Botulism in endemic areas | Maternal antibodies interfere with early vaccine response — timing matters |
| Foal (dam unvaccinated) | Begin primary series at 3–4 months | Same considerations | Earlier start due to no maternal antibody protection |
| Senior horse (15+) | Same core vaccines | Same risk-based; discuss immune senescence with vet | Aging horses may have reduced vaccine immune responses; timing and product matters |
Broodmare Vaccination — Why Timing Matters
The timing of a pregnant mare's vaccinations is not arbitrary — it directly determines how much immune protection her foal receives through colostrum. The foal's gut is only capable of absorbing maternal antibodies (immunoglobulins) for the first 12–18 hours of life. Antibody levels in colostrum peak when the mare's immune response to vaccination is highest — approximately 4–6 weeks post-vaccination.
This is why core vaccines are given to broodmares 4–6 weeks before their expected foaling date, not at their convenience or on an arbitrary schedule. A mare vaccinated in November for a February foaling delivers peak antibody transfer; a mare vaccinated at foaling delivers minimal protection.
| Vaccine | Timing in Pregnancy | Why This Timing | Important Caution |
|---|---|---|---|
| EHV-1 (Rhinopneumonitis) | Months 5, 7, and 9 of gestation | Repeated boosters maintain high antibody levels against EHV-1 abortion through the highest-risk period | Only killed (not MLV) EHV products in pregnant mares |
| Core vaccines (EEE/WEE, Tetanus, WNV, Influenza) | 4–6 weeks before expected foaling | Peak antibody levels in colostrum at foaling — maximum transfer to foal | Confirm with your vet whether all products are pregnancy-safe |
| Rabies | Annually — timing flexible; before foaling if due | Annual requirement; consult vet on specific product and timing | Some products labeled for use in pregnant mares; confirm label |
| Botulism | First trimester or per vet recommendation | Foal protection through colostrum in endemic areas | Particularly important in Kentucky and states with high botulism soil burden |
Coggins Test (EIA) — Not a Vaccine, But Essential
The Coggins test is a blood test for Equine Infectious Anemia (EIA) — a viral disease with no treatment and no vaccine. It is not a vaccination, but it is required for interstate transport and the vast majority of competitive events. A current negative Coggins certificate (within 6 or 12 months depending on jurisdiction) must accompany the horse.
EIA is transmitted through blood-to-blood contact — primarily biting flies and contaminated needles. Horses that test positive (coggins-positive) must be permanently quarantined or euthanized under state and federal regulations. Annual testing is required for travel; many boarding and show facilities require it regardless of travel.
Administering Vaccines — Owner vs. Veterinarian
Core equine vaccines are available for owner purchase and administration. Many experienced horse owners vaccinate their own horses with no problems. However, there are meaningful considerations that support veterinarian administration, particularly for horses with complex health histories.
Arguments for Veterinarian Administration
- Veterinarians can assess the horse's health status before vaccinating — sick or febrile horses should not be vaccinated
- Systemic vaccine reactions require epinephrine and veterinary management — rare but life-threatening; your vet is equipped
- Modified live intranasal Strangles vaccine carries handling risks that non-professionals may underestimate
- The annual visit provides examination, dental check, BCS assessment, and deworming review beyond the vaccination itself
- Records are maintained in a professional health file — important for competitions, insurance, and resale
When Owner Administration Is Reasonable
- Horse owner experienced with injection technique and has administered vaccines before without complications
- Core vaccines only (not MLV Strangles intranasally)
- Epinephrine is on hand and the owner knows the signs of anaphylaxis
- The vaccination is part of a veterinarian-guided overall health program
✅ Setting Up Your Annual Vaccination Program
- Schedule a veterinary consultation to review your horse's current vaccination status and develop a protocol appropriate for use, region, and exposure
- Research regional disease activity — ask your vet which diseases are currently active in your county or at events you attend
- Plan spring timing for EEE/WEE and West Nile — before mosquito season; early spring vet visit aligns well
- Performance horses: schedule Influenza and EHV boosters every 6 months; track when these fall relative to major competitions
- Maintain vaccination records — keep a binder or digital record of dates, products, and lot numbers; required for interstate travel Coggins and competition paperwork
- Confirm Coggins timing — schedule annual EIA testing at the same spring visit; don't let it lapse before an event
📋 Ongoing Vaccination Program Discussion Points for Your Vet
- Which risk-based vaccines matter most for your specific county and event circuit — your vet knows local disease patterns
- Semi-annual vs. annual Influenza and EHV boosters — for horses competing at multiple shows per year, 6-month intervals are AAEP recommended
- Strangles vaccination decision — horses with recent exposure or high antibody titers may risk purpura with killed vaccine; discuss
- Pregnant mare protocol — confirm exact timing, product selection, and what's appropriate for each trimester with your reproductive vet
- Foal primary series timing — based on dam vaccination status, regional risk, and foal health at first visit
- Aging horse immune response — some senior horses benefit from more frequent boosters; discuss with your vet
- Vaccine reactions — record and report any reaction to your vet before the next vaccination cycle
Questions to Ask Your Veterinarian
- Given my horse's specific use and where we compete, which risk-based vaccines do you recommend adding?
- Should I be vaccinating for Influenza and EHV every 6 months, or is annual sufficient for my horse's exposure level?
- What is your recommendation for Strangles vaccination — MLV intranasal or killed IM — and what are the tradeoffs?
- For my pregnant mare: confirm the exact vaccine schedule and whether all products I'm currently using are appropriate during pregnancy
- My horse had a reaction to a vaccine last year — how do we approach this year's vaccination?
- Is the Coggins test current, and when does it expire for the events we have planned?
