Equine vaccination.

Why should my horse be vaccinated?

Vaccinations protect your horse against life threatening diseases such as tetanus, and diseases that can severely affect its health and performance, such as equine influenza (flu) and herpes virus infection.

Vaccination is the only proven method of protecting against these diseases: there is no specific cure for them and treatment may be not only unsuccessful but extremely expensive.

The organism which causes tetanus, Clostridium tetani, lives in the soil, and is rife in most areas. It enters tissues through wounds and horses are particularly susceptible. If a horse has not been immunised, it is likely to need tetanus antitoxin for even minor wounds or when it undergoes a surgical procedure. The organism thrives without oxygen: it can enter a small puncture wound, such as a nail or thorn prick, which may well go unnoticed. If the antitoxin is not given, the often fatal disease can take hold. Vaccination provides protection against this happening.

The high percentage of horses within the UK which are regularly vaccinated is believed to be a major factor in reducing the numbers of large epidemics of influenza. Moreover the incidence of clinical disease during an outbreak is markedly reduced when the equine population is protected by vaccination.

These diseases, preventable by vaccination, have not been eradicated: your horse might come into contact with them. Booster vaccination is an effective way of ‘topping up’ a horse’s immunity thereby minimising the risk of disease when challenged by natural infection.

What should my horse be vaccinated against?     

The most common diseases to vaccinate against in the UK are tetanus and equine influenza. Other vaccines are available in the UK for Equine Herpes Virus (EHV), rotavirus, Equine Viral Arteritis (EVA) and Strangles. The need for your horse to be vaccinated against any of these pathogens will depend on its use and disease pressure from the environment. Your vet can advise you if any of these vaccines are likely to be helpful for your horse.

When should my horse be vaccinated?

Your vet will advise you on the best time, and the frequency of booster vaccinations, based on the manufacturers’ recommendations for the vaccine he or she chooses to use.

Many competitions require proof of flu vaccination. It is a sensible precaution to vaccinate before exposing your horse or pony to any situation where it will mix with large numbers of horses from different environments. Also, the introduction of a new horse to your stable could present a potential for exposure to infection.

You may find your vet’s advice on when to revaccinate for equine flu differs depending on the type of shows you take your horse to; from Jockey Club to FEI (Federation Equestre Internationale) rules.

I have heard vaccines can cause side effects: is this true?

Serious side effects following vaccinations are extremely rare. Although all veterinary vaccines undergo thorough, independent evaluation of their safety, efficacy and quality, occasional reactions may occur in individual cases. This may be an injection site reaction, allergic reaction or general malaise. No more than one horse in 100 appears to show any reaction at all.

If your vet thinks your horse is one of the very few that has suffered a local or overall reaction to a vaccine, there is a system called the Suspected Adverse Reaction Surveillance Scheme, operated by the Veterinary Medicines Directorate, where reports should be made. Horse owners themselves can also make reports direct. This scheme keeps an overall check on adverse reactions.

The results of the VMD’s SARSS scheme are published1 and other preliminary studies also indicate a low rate of apparent adverse reaction2. It must be remembered that the very small risk of a vaccine side effect is greatly outweighed by the benefit of protection against serious disease.

Under EU and UK law all horse vaccines used in the UK must be licensed for use here and be prescribed by your horse’s vet. Always avoid any temptation to by-pass this system by using foreign or otherwise illegal products.

Does my horse need rest after vaccination?

No. This was a recommendation for older vaccines, and is no longer stipulated with more modern vaccines. Nevertheless, talk to your vet, as he or she will be able to offer tailor-made advice for your particular horse and the work it is doing.

What should I do if I think my horse is ill following vaccination?

Consult your vet. If a horse shows signs of respiratory disease following a vaccination, it is quite likely that it was harbouring an infection prior to vaccination and the problem has arisen coincidentally. The vet may well recommend a ‘minimum dust’ management regime and perhaps prescribe therapeutic drugs.

In the past, flu vaccines in both man and animals had the reputation of not working well. Equine flu vaccines were developed in the mid 1960’s in response to the worldwide epidemic of the ‘Miami’ strain, and were not terribly effective. Things have moved on immeasurably since then. Manufacturers regularly update their ‘flu vaccines to ensure they are effective against the latest strains of ‘flu virus.

Homeopathic vaccines: what about them?

Whether for disease prevention or treatment, the veterinarian and the horse owner have a right to expect that the preparation of animal medicines is reliably based on the triple standards of quality, safety and efficacy. The extremely stringent requirements for product registration reflect this.

The main concern most vets have about the use of homeopathic ‘vaccines’ (nosodes) is that there is no proper independent evidence to show that they are effective in protecting horses.

Indeed, the few properly designed trials that have been carried out by using homeopathic nosodes have shown no evidence of protection. Without evidence of effectiveness, homeopathic nosodes may pose far greater risk to horses and their in-contacts by leaving them susceptible to disease.



Gray, A (1998) Suspected adverse reactions. Vet Rec (1999) 145, 93.

Mair, T S (1988) Adverse reactions to equine vaccinations: A preliminary survey. Vet Rec 122, 396.


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