Why and how to vaccinate your horse

Why do we vaccinate horses?

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 not only be unsuccessful but extremely expensive.

The organism which causes tetanus, Clostridium tetani, lives in the soil, and is rife in some areas. It enters tissues through wounds, and horses are particularly susceptible. If a horse has not been immunised, it is likely to need a shot of 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. Even when antitoxin is given, the often fatal disease can take hold. Only vaccination provides long term protection against this happening.

Equine Influenza (flu) is a respiratory virus that spreads very easily from horse to horse. It causes the horse to be lethargic for several weeks, and signs often include a nasal discharge, fever and coughing. Equine Influenza outbreaks are still regular occurrences in the UK, and the only reason that they remain confined to a small area is because so many horses and ponies are now vaccinated. We particularly recommend ‘flu vaccinations in all youngstock and older horses, all horses that mix with horses from other yards e.g. competing or hacking out, and all horses kept on yards with different horses arriving and leaving. Influenza vaccination is required for horses competing or going to training events under most governing bodies, e.g. riding and pony clubs, BSJA, BE, BD and under Jockey Club rules.

Equine herpesvirus is a common virus that occurs in horse populations worldwide. The two most common strains are EHV-1, which causes abortion, respiratory disease and paralysis, and EHV-4, which usually causes respiratory disease only but can occasionally cause abortion.
EHV abortion can occur from two weeks to several months following infection with the virus. It usually occurs in late pregnancy (from eight months onwards) but can happen as early as four months. Respiratory disease caused by EHV is most common in weaned foals and yearlings, often in autumn and winter. However, older horses can succumb and are more likely than younger ones to transmit the virus without showing signs of infection. Although EHV-1 causes outbreaks of abortion, EHV-4 has only been associated with single incidents and is not considered a risk for contagious abortions.

These diseases have not been eradicated in the UK: your horse might come into contact with them. Following the primary course of vaccinations, booster vaccinations are 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 are tetanus and equine influenza. Other vaccines exist for herpes, rotavirus and EVA (equine viral arteritis).

When should my horse be vaccinated?

Different vaccines have different protocols. Usually tetanus and equine influenza start after 5months of age.


Tetanus requires two injections for the primary vaccination course.
Primary vaccination
Two injections with an interval of 4-6 weeks between them, from 5 months of age.

Booster vaccination
One dose should be given up to 36 months after the primary course, repeated at intervals of up to 36 months.

Equine Influenza

Equine Influenza vaccination timings are a little more complicated and depend upon what you wish to do with your horse. It is the owner’s responsibility to determine which protocol to follow.

Manufacturers' recommendations are:

a. Primary course: 2 injections, 28-42 days apart. 
b. First booster: 182 days (6 months) after 2nd primary injection. 
c. Following boosters: Annually (within 365 days of preceding booster).  However, if in a high risk group (competing, showing, etc.) or during an outbreak, boosters should be given every 6 months.

The Jockey Club vaccination schedule is:

a. Primary course: 2 injections, 21-92 days apart. 
b. First booster: Within 150-215 days of 2nd primary injection. 
c. Following boosters: Annually (within 365 days of preceding booster). Advised to be given more frequently during an outbreak.

The FEI vaccination schedule is:

a. Primary course: 2 injections, 21-92 days apart. 
b. First booster: As per manufacturers' recommendation
c. Boosters: Every 6 months (may be extended by a maximum of 21 days).

Equine Herpesvirus

The vaccination schedule varies depending on whether the horse is being vaccinated to reduce the risk of abortion or to protect against respiratory disease.

Respiratory disease:

a: Primary course: 2 injections, 28-42 days apart from 5 months of age.
b: Boosters: every 6 months.

Foals at risk, due to consuming insufficient colostrum or early exposure to field infections should be vaccinated from 3 months of age, followed by the full primary course.

Pregnant mares should be vaccinated during the 5th, 7th and 9th month of pregnancy as an aid in reducing the risk of abortion.

Can I ride my horse after they have received their vaccination?

We normally suggest only light work (i.e. not getting into a sweat) for 24-48 hours after the vaccination. Vaccination reactions are rare, and if they occur are usually confined to a soft tissue swelling where the injection was administered.

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 infection.

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