The Pony Club: leading a revolution?

Any vet doing equine work has had that awkward moment at a visit when the booster vaccination for equine influenza (EI) is a couple of days late and you casually enquire whether the horse competes.

When this predicament, and the need for a restart, is pointed out to the owner, it usually incites a range of excuses – such as “but I didn’t get a reminder“ or “no one has ever told me it needs to be within the year“ – to try to manipulate you into either (a) vaccinating the pony and back-dating the passport, or (b) offering to shoulder the cost of the extra vaccinations needed to restart the course.

According to The Jockey Club‘s rules, horses should receive a course of three initial EI vaccinations (first vaccination followed 21 to 92 days later by the second, and the third vaccination 150 to 215 days after the second) followed by annual boosters within 365 days. It is also well known it is not only The Jockey Club that sticks strictly to these guidelines, but also affiliated bodies (such as the British Showjumping Association, British Dressage and British Eventing), all pony clubs and most riding clubs.

So, when little Johnny’s 12 hands high pony is due to go to The Pony Club camp next month, and you announce it needs to restart its vaccination course before it goes, the aforementioned scenario happens. This sometimes induces a very stroppy client – or worse, as happened to the author last year, the pony and child were not able to go to The Pony Club camp at all. Cue the tears.

As you get older and wiser (or maybe less affected by difficult clients), you become very adept at explaining why neither option A or B is viable. Firstly, as a professional, false certification should never be considered. The RCVS views false certification as grounds for suspension at least, and several high-profile cases have discouraged the rest of us from back-dating vaccination records. Therefore, it is just not worth your career to do so. Also, as often mentioned to owners, most vaccination reminders are computer-generated and are a helpful bonus offered by most practices for owners, but these cannot be guaranteed.

I often say to owners they need to make a note of when their horse’s vaccination is due as it is their responsibility.

New rules

The Pony Club released new rules in 2018 that allowed two weeks‘ grace on EI booster vaccinations and relaxed the initial protocol, albeit with caveats – for example, at the discretion of the veterinary officer.

In a practical world, surely this can only help us first opinion equine vets. We all seem quite confident a pony’s immunity to influenza extends over 365 days, and a slightly late booster is enough to stimulate an adequate immune response for the following year, like in small animal vaccinations.

But are we sure our population of equids will remain protected if the rules relax? Does the literature support the use of influenza vaccinations in this way?

Many studies have been done collecting information about antibody response to EI vaccinations. It has been shown if a horse starts its influenza (and indeed, tetanus) vaccination course at six months of age, and complies with the initial course on the data sheet with annual boosters, then, as the horse gets older, the number of antibodies to influenza virus increases with age after each vaccination. Therefore, the horse’s immunity to EI increases with age provided data sheet protocols are followed¹.

Interestingly, studies² have shown using different vaccine products for the initial course of three vaccines produces a better immune response than using the same product and, it is thought, the different adjuvants improve the immunological response.

The question is do horses still have good immunity to influenza at day 365 post-third vaccination of the initial course – that is, at the annual booster and at subsequent boosters? If that is the case, The Pony Club can safely relax its rules by 14 days, and be comfortable, at day 379, the ponies have a similar immunity, and the annual booster will stimulate the immune system to increase the antibodies back to sufficient levels.

The literature^1,2 has shown horses have good serological change at these boosters, and that it is likely to continue for at least two weeks on from this point. Therefore, we should be able to relax and take the practical approach, and know our “slightly out-of-date“ vaccinated ponies are protected from the really nasty clinical symptoms of full-blown flu.

Outdated protocol

It has also been noted most horses, when first vaccinated as youngsters, have a period of time between the second and third vaccination in the initial programme (12 to 20 weeks post-second vaccination), where their antibody titres fall below the adequate number required for an effective immune response to an EI viral challenge³. Not only that, the data sheets for all available UK influenza vaccinations⁴ stipulate the second vaccination should be four to six weeks after the first vaccination, so why do The Jockey Club rules allow the second vaccination to be done up to 92 days after the first?

It appears, therefore, our protocols for the initial course of influenza vaccines do seem to be a little outdated. It appears best if we give the second vaccination four to six weeks after the first, and then the third vaccination 12 weeks post-second vaccination, rather than five to seven months later^3,5.

Zoetis states in its data sheet for Equip F or FT that booster vaccinations can be given at 12 to 15-month intervals⁴. So, having reviewed the literature, The Pony Club appears to be leading the way. It has finally taken the plunge and these ponies are allowed to go to camp or rallies. Who knows whether the affiliated bodies will follow suit. An argument definitely exists these more professional groups should not relax their rules, but, perhaps, the vaccination companies and The Jockey Club should be updating their protocols.

Practically, the riding clubs should probably join The Pony Club. Equine vets all over the UK will, no doubt, thank it as we are far less likely to upset our clients and not be asked to jeopardise our veterinary careers. This can only be a good thing.

Despite this, I can still imagine, on day 383, an owner saying “but it’s only a few days over“. You’ll never change some clients, I guess.