Vaccinations

What are the different types of vaccines?

Live and killed vaccines stimulate an immune response in horses to

protect them against infectious diseases such as ‘flu, EHV, tetanus

and strangles.

_ Live (attenuated) vaccines Live vaccines are derived from live

organisms or intact viruses which are treated until they lose

their capacity to induce the disease fully within the horse, but

retain the capacity to trigger the immune system. Live vaccines

are usually more effective than inactivated vaccines as they

multiply within the horse and produce more antigens, but they

are often much harder to produce.

_ Killed (inactivated) vaccines Inactivated vaccines are produced

when organisms are killed off by heat or chemicals and then

introduced into the body to stimulate immunity. Antigens are

introduced to a horse’s body in a dose of vaccine and there is

no multiplication within the horse following vaccination.

Therefore, two doses of an inactivated vaccine are normally

required to stimulate immunity, and prolonged immunity

requires the administration of additional doses known as a

booster.

Rules and regulations

It is advisable to vaccinate all horses that regularly encounter large

groups of unfamiliar horses, for example hunters and horses that

take part in Riding Club and Pony Club activities.

Riders or trainers who compete under the International Equestrian

Federation (FEI) or Jockey Club rules, have to ensure their horses’

vaccinations are up-to-date to enable them to compete. Most

competitions do not permit vaccination within seven days of the

event.

_ Jockey Club rules The Jockey Club rules stipulate that a horse

must have two primary vaccinations against ‘flu given no less

than 21 days apart and no more than 92 days apart. In addition,

where sufficient time has elapsed subsequent to the primary

vaccinations, the vaccination section of the passport must

be completed to show that:

_ A horse has received a booster vaccination given no less

than 150 days and no more than 215 days after the second

component of the primary vaccination, and

_ A horse has received booster vaccinations at intervals of not

more than a year apart or such lesser time as the Stewards

of the Jockey Club may, in an emergency, decide.

_ FEI rules Horses competing in FEI competitions require a

primary course, in accordance with Jockey Club guidelines, but

importantly a booster every six months.

Frequently asked questions

Why should I vaccinate my horse?

Vaccination is the only proven means of helping protect horses

against potentially fatal diseases such as equine ‘flu, tetanus,

EHV and strangles which can severely affect a horse’s health

and performance.

_ What should my horse be vaccinated against?

The most common diseases to vaccinate against are equine ‘flu

and tetanus, although it is also advisable to protect your horse

against EHV and strangles. Your vet will be able to advise you

on a vaccination or prevention programme and the frequency of

booster vaccinations. If you are concerned about any diseases

during breeding, for example rotavirus, you should also talk to

your vet for information on a suitable prevention programme.

_ How often should I vaccinate my horse?

Booster vaccinations for respiratory disease are required from

every three months to fifteen months, depending on the vaccine.

Your vet can advise you on this.

_ How effective is vaccination?

As in humans, vaccination is never a 100% guarantee since it

relies on the ability of each horse to individually mount a

satisfactory immune response. As a result, you should never

vaccinate a horse that is unhealthy or stressed. A combination

of having a complete vaccination programme and enough of the

population vaccinated (herd immunity) is how viruses and

bacteria are kept at bay. The gold standard is to have a whole

yard vaccinated and follow good stable management and

hygiene procedures. This will reduce the amount of infective

organism in the horse’s environment.

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

Just as humans sometimes feel unwell following immunisation,

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.

An overview of infectious respiratory diseases

Equine ‘flu ‘Flu is a highly infectious viral disease which affects

the respiratory tract including the windpipe and lungs.

Widespread throughout the horse population, the virus spreads

rapidly, due to a combination of a short incubation period of

one to three days and coughing during early stages of the

disease. ‘Flu is transmitted by direct horse-to-horse contact and

indirect contact via humans, tack, feed and equipment.

_ Equine Herpes Virus (EHV) Equine Herpes Virus is a viral

disease which can cause severe loss of form and associated

problems including abortion and paralysis and, as in humans,

the virus can recur time after time. It’s estimated that a staggering

75% of horses become ‘silent’ carriers, able to pass it on to

others without displaying any signs.

The disease can also remain dormant in previously infected

horses and can be reactivated by ‘stress’ factors such as

transport, competing, a change in environment and - in the

case of youngsters - weaning, sales and breaking-in.

_ Strangles Strangles is a highly contagious disease caused by

the bacterium, Streptococcus equi. Whilst the incubation period

of strangles is approximately two weeks, infected horses can

release the bacterium for long periods, so new outbreaks can

occur up to three weeks after the initial outbreak. About 10%

of horses can carry the disease after an infection of strangles

up to a year previously.

Strangles is transmitted by direct and indirect contact and

particularly through shared water sources, where the bacterium

lives for longer periods. It can affect all ages and types, but

those most at risk are youngsters; those kept in large numbers

that mix with others and horses that travel a lot to competitions

and riding club events.