Why Vaccination Matters for Horses
Vaccination stimulates the immune system to produce protective antibodies against specific pathogens without causing disease. In horses, several infectious diseases can spread rapidly through yards and competition venues, cause severe illness or death, or result in catastrophic reproductive losses. Core vaccination programmes protect individual animals and contribute to herd immunity, reducing the overall burden of disease within the UK equine population.
All vaccinations should be administered by a veterinary surgeon, and an accurate vaccination record must be kept in the horse's passport. For horses competing under FEI, British Equestrian, or Racing regulations, specific vaccination schedules are mandated and checked at competitions. Failure to comply can result in disqualification or exclusion from the venue.
Equine Influenza
Why It Matters
Equine influenza is a highly contagious respiratory disease caused by influenza A viruses, primarily subtypes H3N8 and H7N7. It spreads rapidly through airborne droplets at competitions, sales, and livery yards. Clinical signs include sudden fever, a harsh dry cough, nasal discharge, and lethargy. Outbreaks can affect entire yards within days and result in prolonged lay-off from work.
Vaccination Schedule
The standard primary course consists of two injections given between twenty-one and ninety-two days apart. A first booster is required within 150 to 215 days of the second primary injection. Subsequent boosters are then given at intervals of no more than twelve months (annual boosters). Some competition bodies, including the FEI and British Horseracing Authority, require boosters every six months.
FEI Requirements
The FEI has specific and strictly enforced equine influenza vaccination rules. Horses competing at FEI events must have completed the primary course and must have received a booster within 6 months and 21 days of the competition date. There is also a mandatory stand-down period: horses may not compete within seven days of receiving any influenza vaccination. Passports are checked at the venue and any breach of the rules results in exclusion. Horse owners competing under FEI rules should plan vaccination timing carefully with their vet well in advance of the competition calendar.
Tetanus
Why It Matters
Tetanus is caused by the toxin of Clostridium tetani, a bacterium found in soil and horse dung. Horses are particularly susceptible to tetanus — more so than most other domestic species. The bacterium enters the body through wounds, even very minor ones such as puncture wounds in the sole of the foot, and produces a potent neurotoxin that causes progressive muscle spasm, an inability to eat or drink, and ultimately death. The mortality rate in unvaccinated horses is extremely high. Tetanus vaccination is non-negotiable and should be considered a core vaccine for every horse in the UK.
Vaccination Schedule
The primary course consists of two doses given four to six weeks apart. A booster is administered twelve months after the second primary dose, and then every two years thereafter in horses not receiving annual influenza boosters. Where combination influenza and tetanus vaccines are used, the tetanus component is covered by the annual booster. Any horse with an uncertain vaccination history or that sustains a wound should receive a tetanus antitoxin (immediate protection) in addition to starting or resuming a vaccination course.
Equine Herpesvirus (EHV-1 and EHV-4)
Why It Matters
Equine herpesviruses are endemic in horse populations worldwide. EHV-1 and EHV-4 are the strains of greatest clinical importance in the UK. EHV-4 primarily causes respiratory disease, whilst EHV-1 is associated with respiratory disease, abortion storms in pregnant mares, and — in some cases caused by neurotropic strains — equine herpesvirus myeloencephalopathy (EHM), a devastating neurological condition. EHV-1 abortion outbreaks can devastate stud farms, with multiple mares aborting in rapid succession. There is no licensed vaccine in the UK that claims to prevent EHM, but vaccination against EHV-1 is recommended to reduce viral shedding and the risk of abortion.
Vaccination Schedule
EHV vaccines are licensed for the prevention of respiratory disease and abortion. Pregnant mares on studs or in mixed-use yards should be vaccinated at five, seven, and nine months of gestation to reduce the risk of abortion. Sport horses and competition horses at higher risk of exposure benefit from six-monthly boosters. As EHV is not a mandatory vaccination for competition entry in most disciplines, uptake is lower than for influenza and tetanus, but it is strongly encouraged by vets for horses on busy yards or in regular contact with large numbers of other horses.
West Nile Virus
West Nile Virus (WNV) is a mosquito-borne flavivirus that causes neurological disease in horses and humans. It is not currently endemic in the UK, and the risk to UK horses is considered low. However, a licensed vaccine is available for horses in the UK, and it may be recommended for horses travelling to continental Europe, particularly southern and central regions where the virus is now established and has caused significant outbreaks in recent years. Horses travelling abroad for competition should discuss the need for WNV vaccination with their vet well in advance of travel.
Combination Vaccine Products
Several combination vaccine products are available in the UK that allow equine influenza and tetanus to be administered in a single injection, reducing the number of separate veterinary visits required. Commonly used combination products include Equilis Proteq Flu-Te and Prestige Flu-Te. These products must comply with the same vaccination schedules as single-component vaccines, and the FEI and other competition bodies accept them provided the required intervals are met. Your vet will record each vaccination in the horse's passport with the product name, batch number, and date, all of which must be legible and unaltered for competition purposes.
Practical Tips for UK Horse Owners
- Always ensure vaccinations are recorded correctly in the official horse passport at the time of administration — retrospective entries are not acceptable
- Plan FEI competition dates backwards from the required vaccination window — seven days post-vaccination is the mandatory stand-down period
- Do not vaccinate a horse that is unwell, as this can reduce vaccine efficacy and may cause adverse reactions
- Keep a separate diary record of vaccination dates as a backup to the passport
- If a booster is overdue, discuss with your vet whether the primary course needs to be restarted — some products require a restart if the annual booster interval is exceeded
- Foals born to vaccinated mares have maternal antibody protection for the first few months of life; vaccination of foals should be timed with your vet's guidance, typically beginning at five to six months of age
Discussing Vaccination With Your Vet
Every horse's vaccination needs are slightly different depending on their lifestyle, competition activities, yard biosecurity, and health status. An annual vaccination visit is also an excellent opportunity for a general health check, dental assessment referral, and discussion of any changes in condition or behaviour. Building a good relationship with your equine vet and maintaining an up-to-date vaccination programme is one of the most important things you can do for your horse's long-term health and welfare.