The disease spreads very rapidly so vaccination is often compulsory for horses entering competitions. You should make sure your own horse is fully protected before it mixes with new animals.
New born foals should start their flu vaccinations from four months of age, although young animals may require more initial vaccinations than an older horse due to the persistence of antibodies that they received from their mother. The initial course for an adult is two injections given 4-6 weeks apart, and a first booster is required 5 months later.
Following this first booster, the manufacturer’s recommendation for subsequent vaccination should be followed, normally every 12 months. For most governing bodies this is sufficient for competition. However, some organisations are now insisting on a minimum period of 6 months between vaccinations for competitions. Be careful to check the rules of any competition before you leave for an event.
Please note many competitions abide by FEI rules, whereby a first vaccination (day zero) is followed by a second 21-92 days later, and then a third within 6 months plus 21 days of the second. Many competitions accept third vaccination falling between 150 and 215 days (source:Liphook) after the second, and we try to use this rule in practice. The booster should be given within 1 year, after which the competitions rules will likely require a horse to restart the course. It is of utmost importance that you check when your horse is due vaccination and book in to have it done. While we aim to provide reminders, this is as a courtesy only and should not be relied upon.
If any, there are usually only mild side-effects to a flu vaccine. Sometimes, horses can feel off-colour for 24-48 hours following the vaccine and, if this is the case, they should not be worked in the following days. If more severe reactions occur, then you should always contact your veterinary surgeon.