Vaccination plays an essential role in helping to prevent disease in our horse population. In the UK, we vaccinate horses against a number of diseases, many of which can be fatal or debilitating. Routine core vaccinations protect against equine influenza and tetanus. Other vaccines, such as EHV and Strangles, may be given according to your horses’ risk profile, but these are less common and the risks and benefits should be discussed with your vet.
How do vaccines work?
Vaccines are designed to teach your horses’ immune system how to fight a particular disease by fooling it into believing that it is being attacked by the organism causing that disease, inducing the production of protective antibodies and stimulating other immune mechanisms.
Usually, we will give your horse a primary course of injections followed by regular boosters, the frequency of which depends on the type of vaccine and the duration of immunity induced.
A ‘naive’ or unvaccinated horse exposed to a new disease is vulnerable to infection. For example, almost 100% of naive horses exposed to the flu virus will develop symptoms of the disease. Furthermore, flu is an adaptive virus that changes its character over time. Vaccine manufacturers routinely update their products to protect against new and emerging strains.
Are vaccines safe?
Decisions about vaccination should be the result of careful assessment of the risks and benefits to your animal. Although all interventions carry some degree of risk of an adverse reaction, in the case of the core flu and tetanus vaccines, refusing vaccination leads to a higher risk of harm than vaccinating does.
Diseases such as distemper in dogs and flu in horses are now relatively rare, and this is in no small part due to the success of vaccination. But that is no reason for complacency. In 2007 Australia experienced a devastating equine influenza outbreak, with large numbers of horses falling prey to the disease and suffering greatly. The Australian national equine industry was shut down for months and incurred millions of dollars worth of damages.
Nonetheless, some horses are not good candidates for vaccination, for example the chronically ill or the very young. In this instance, the concept of herd immunity is essential – if 90 percent of the population in a herd is vaccinated, the remaining 10 percent will clearly have some protection conferred on them as the disease is denied the opportunity to circulate.
Vaccines are not usually covered by insurance companies, but they are relatively inexpensive – especially given the cost of treatment for vaccine-preventable diseases – and some may be specifically required for travel and/or competition.
What if I know my horse does not respond well to being vaccinated?
Some horses develop transient reactions when they are vaccinated, such as a sore neck. In general such reactions resolve within 24hrs. If you know your horse suffers from this type of reaction, please tell us when you book your appointment so that we can minimise your horses’ discomfort, for example by changing the type of vaccine, our choice of injection site or by giving an anti-inflammatory injection at the same time as the vaccine.
In the small number of cases where significant adverse reactions occur, robust procedures are in place to allow front line vets to inform manufacturers and their regulatory bodies, ensuring the risk of repeated events are minimised.
How soon can I ride after a vaccination?
You should try to reduce stress such as heavy exercise for 24-48 hours after vaccination. This will further reduce the very small chance of an adverse reaction. In most cases very light work such as a short hack can continue uninterrupted.
Equine Influenza (flu)
Equine flu causes fever, depression, lethargy, coughing and a watery or snotty nasal discharge. Disease spreads quickly between unprotected horses as the virus can travel great distances in the air. People travelling from infected to naive horses can also transmit infection by carrying virus particles on their hands, clothes or equipment. Although it is possible for vaccinated horses to become ill, the course of the disease is usually significantly shorter and the symptoms much less severe.
For competition purposes horses must have at least their first two injections and cannot compete within 7 days of any injection.
It is important your horse has its booster vaccination within 365 days of its previous booster otherwise the whole course will need to be re-started. There is no leeway for competition. The office will be happy to work out dates for you and reminders are sent where possible, but responsibility for ensuring compliance remains with the owner.
Vaccinated pregnant mares should by given a tetanus booster in the last 4-6 weeks of pregnancy, which will provide their foals with passive protection through the mare’s milk for the first 6-12 weeks of life.
Horses are particularly vulnerable to tetanus but it is readily preventable through vaccination – every horse should be protected in this way. Tetanus is caused by a soil-dwelling bacterium, Clostridium tetanii, found readily in the environment. The bacteria invade the body through cuts and grazes, and horses often acquire it through puncture wounds such as penetrations of the sole of the foot.
The bacteria multiply in the body and produce a toxin that causes a progressive rigid paralysis of the horse’s muscles. The horse becomes stiffer, adopting a rigid stance with an elevated tail head, and may also appear anxious and become sensitised to sensory stimuli such as touch, sound and light. Ultimately the horse has trouble eating, standing and breathing and even if treatment is instituted most will succumb to respiratory failure.
Vaccination is arguably medicine’s greatest triumph. Take advantage of it by working with us to design a schedule that suits you and your horses.