Cian O'Connor disqualified for dexamethasone

The event took place three months ago. In the CSI2* Tour of San Miguel de Allende, Mexico, Cian O’Connor rode the now nine-year-old Rhineland gelding Pegasus, a Checkter son who began his career with Manuel Feldmann and Tobias Kuhlage under the name “Checkmate”. Cian O’Connor has been riding the gray since mid-2025.

During the routine doping control in San Miguel de Allende, where Pegasus had his first outing in a 1.45 meter Grand Prix, the substance dexamethasone was found, a potent anti-inflammatory that falls under the category of “controlled medication”. This includes substances that are generally allowed to be used in the treatment of horses, but not at competitions.

If the horse tests positive for a substance from this category for the first time, the “Person Responsible” – the rider, in this case Cian O’Connor – has the option of using the FEI’s Fast Track procedure. In this case, the pair will be disqualified from the competition at which the positive sample was taken and a fine must be paid. However, no ban is imposed on either the rider or the horse.

Cian O’Connor chose this option. The horse was disqualified from the competition and fined 1,500 Swiss francs (just under 1,620 euros) and reimbursed 1,000 Swiss francs (just under 1,100 euros). Should the horse test positive for a substance from the “Controlled Medication” category again in the next four years, the matter will go before the FEI tribunal.

Statement O’Connor

Cian O’Connor says he cannot explain how the substance got into the horse’s body. He told the Irish Independent: “I have stated categorically to the FEI that neither I nor my team administered any such medication to the horse.”

He sees external circumstances as a potential cause: “In recent months, I have traveled a lot from continent to continent to take part in various competitions. I have often used local feed, bedding and transportation that did not belong to me or was not under my control.”

“I would like to firmly emphasize once again that neither I nor any member of my team administered such medication to my horses during this time.”

We have asked O’Connor’s Karlswood team once again whether they have made any further progress in investigating the cause and will add the answer here as soon as it is available.

Cian O’Connor, rider, entrepreneur, prevented Olympic champion

Cian O’Connor has been a mainstay on the Irish show jumping scene for decades. He has competed at four Olympic Games and won individual bronze with Blue Loyd in London in 2012. He has also competed in four World Championships and six European Championships. In 2017, he was part of the winning team at the European Championships in Gothenburg, where he also won bronze in the individual competition.

In addition to his own career, Cian O’Connor also trains other riders, including the Wachman siblings from the famous Coolmore racing stable and gallop stud, which is now also known as Coolmore Showjumping.

O’Connor has bought several horses for himself and his students in recent years, including some from Germany. For example, David Wills C Vier switched to O’Connor after the 2021 European Championships and rode with him at the 2022 World Championships. The Holsteiner Cardento son was then sold on to Isabella Russekoff, who competes for Israel.

O’Connor took over the OS stallion Chacco’s Light, bred by Ewald Brüggemann, from Maurice Tebbel in the fall of 2023. He was nine years old at the time and had already enjoyed considerable success with Tebbel, including a victory in the Nations Cup in Brussels. When O’Connor brought the Chacco’s Son son into his stable, he was renamed Fermoy after an Irish town where Coolmore Stud has branches. Fermoy is now also listed as a gelding. In 2024, O’Connor placed with him in Rotterdam, Hickstead, Dublin and Calgary, among others. In 2025, the gelding only rode half the season, was placed in Rome, but has not competed since June. He is not yet registered with the FEI for 2026.

Cian O’Connor was already highly successful as a junior and young rider. His first senior championship was the 2002 World Equestrian Games in Jerez, where he competed with Waterford Crystal. The team finished in seventh place. They came fifth at the 2003 European Championships in Donaueschingen. In 2004, they were nominated for the Olympic Games in Athens and jumped to victory there. However, O’Connor cannot call himself an Olympic champion, as he was stripped of the title after Waterford Crystal – a Holsteiner by Landgraf I – tested positive for the banned substance fluphenazine during a doping test. This is an antipsychotic used in human medicine to treat schizophrenic disorders and the like.