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Key Facts About Horse Vaccination

To ensure your horse’s health is maintained to a high standard, it is important to have your horse vaccinated. Below are the answers to some of the frequently asked questions about vaccination.

Why do we need to vaccinate horses?


  • To prevent unnecessary suffering and to promote horse health.

  • To prevent additional unplanned expenses – costs of treatment can far outweigh the costs of vaccination.

  • To prevent loss of use – an unwell horse should not be ridden or exercised until it has completely recovered.

  • To prevent yard closures and sporting cancellations – horse movements on a yard may have to be restricted or cancelled if a horse is diagnosed with an infectious disease.

  • To prevent the spread of disease.
Vet vaccinating horse
Vet vaccinating horse

How do horse vaccines work?

Vaccines stimulate an immune response in horses by tricking their bodies into believing that they are being attacked by a disease. They contain antigens (disease causing organisms) that are altered slightly, so they don’t cause the actual disease, but are still recognisable to the horse’s immune system. This means that the immune system creates a response to fight the 'infection', cells such as antibodies and killer cells act against these antigens. Importantly, memory cells are created at the same time, ready to fight off a natural infection.

When natural infection does occur, the immune system is ‘primed’ and able to produce a much faster and stronger response. It is this rapid and strong response, as a result of vaccination, that causes a reduction in clinical signs seen and a reduction in the spread of disease to others.

What should my horse be vaccinated against?

The most common diseases to vaccinate horses in the UK against are equine ‘flu’ and tetanus, although it is also advisable in some cases to protect your horse against strangles and herpes. Your vet will be able to advise you on the best vaccination schedule for your horse.

If you have a broodmare then it may be advisable to vaccinate her against rotavirus and herpes during pregnancy. Your vet will be able to advise you on the best vaccination schedule for your broodmare.

If you have a stallion then vaccination against Equine Viral Arteritis (EVA) may be appropriate. Your vet will be able to advise you on this.

How often should I vaccinate my horse?

After an initial vaccination course, booster vaccinations for respiratory disease are required at various time intervals, depending on which disease the vaccine is protecting against. Your vet can advise you on the best approach for your horse.

I don’t compete my horse so do I need to vaccinate?

Yes, especially if your horse has any contact with other horses. Furthermore, Equine Influenza Virus can travel up to 5km in favourable conditions so even if your horse lives alone it is still at risk from infection. In 2019 there was a large 'flu' outbreak in the UK and Europe, although such outbreaks are uncommon, it reminded us of the importance of vaccinating for flu in all horses. The disease is debilitating for you horse and can be distressing for you to witness.

A horse doesn’t need to leave home to be at risk of tetanus, as the bacteria is found in soil throughout the UK, and most cases of tetanus are fatal. The only way to prevent your horse from contracting tetanus is by vaccination.

How effective are horse vaccines?

As in humans, vaccination is never a 100 percent guarantee since it relies on the ability of each horse to individually mount a satisfactory immune response. However, outbreaks of disease in vaccinated horses are extremely rare.

A combination of having a complete vaccination program and enough of the population vaccinated (herd immunity) is the best way to reduce the incidence and spread of disease.

The gold standard is to have a whole yard vaccinated and follow good stable management and hygiene procedures.

What should I do if my horse appears sick following vaccination?

Just as humans sometimes feel unwell after a vaccination, horses also can appear off-colour after being vaccinated. This is not usually a cause for concern, but if you are worried you should talk to your vet.

Can I vaccinate my pregnant mare?

Against equine flu and tetanus: It is advisable to keep your pregnant mare up to date with her flu and tetanus vaccinations so that this immunity can be passed to her foal via the colostrum. Most ‘flu/tet’ vaccines are licensed to use in pregnancy. Speak to your Vet about the most suitable time to booster your mare.

Against herpes: To reduce abortion caused by EHV-1 infection pregnant mares can be vaccinated during the 5th, 7th and 9th month of pregnancy.

Against rotavirus: To reduce the incidence of rotavirus within foals, pregnant mares can be vaccinated during the 8th, 9th and 10th months of pregnancy.

Against equine strangles: It is not recommended to vaccinate against strangles during pregnancy.


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