Irish riders Denis Lynch and Billy Twomey were disqualified from competing in the penultimate leg of the lucrative Global Champions Tour series in Rio de Janeiro, Brazil, on Sunday night following positive hyper-sensitivity tests on their horses.
The results of the tests, which include clinical examination and the use of a thermography camera which detects abnormal heat patterns in the skin, were confirmed yesterday by the international equestrian federation, the FEI.
One further horse, ridden by Simon Delestre from France, was also disqualified. The FEI stated that, while there was "no indication of malpractice", all three horses were considered "unfit to compete".
British-based Billy Twomey told the Irish Independent last night that while his horse, Romanov, had some "genuine soreness round his left knee", he believed he was fit to jump.
"When they're on long flights like that they often get little knocks, nicks and and scrapes," he explained. "His left knee did get a bit sore-looking with a bit of dermatitis around it, but I thought he was fine to jump."
The news of the disqualifications has sent a shiver down the spine of the Irish equestrian sports community in the wake of the last two Olympic fiascos.
Both Twomey and Lynch are members of the Irish squad travelling to the European Championships in Madrid next week when Ireland will be battling for one of the last qualifying spots for the London 2012 show jumping team competition.
The governing body for Irish equestrian sport, Horse Sport Ireland (HSI) said in a statement last night that, while the disqualifications were "a major blow for the riders... if the veterinary surgeons present felt the horses should not compete then that has to be respected".
A spokesman for the Olympic Council of Ireland said it would be consulting with HSI in relation to the Rio incident.
Testing is focused on the front of all four legs, with particular attention paid to the area between the fetlock, or ankle joint, and the hoof.
When hyper-sensitivity is found, video evidence is taken and presented to the ground jury which decides if the horse should be disqualified, and no appeal is permitted.
In April 2010, there was a furore when the super-mare Sapphire, ridden by American McLain Ward, was disqualified following a positive hyper-sensitivity test during the closing stages of the World Cup final in Geneva when looking well set to take the title.
FEI veterinary director Graeme Cooke pointed out yesterday that horses can be hyper-sensitive for a number of reasons, including infection, a rash or "malpractice".
"There is no doubt that a horse with excessively sensitive legs may want to jump higher," he said.
Cooke recalled that another of Lynch's horses was disqualified in Aachen during the summer because it had a skin infection that cleared up so quickly that the horse was passed fit to compete the following day.