Hannah Burnett tested positive for Amfetamine at the Ocala Jockey Club 3-Day Event.

Top US eventer Hannah-Sue Burnett and two other riders were provisionally suspended by the FEI on December 21 after testing positive to prohibited stimulants.

All three tested positive to Amfetamine at the Ocala Jockey Club International 3-Day Event in Florida last month, where the CIC3* was won by Burnett and Harbor Pilot, owned by Jacqueline Mars.

Alyssa Phillips also tested positive to Canrenone (a steroidal antimineralocorticoid commonly used as a diuretic) and Jennie Brannigan to Methylphenidate and its metabolite Ritalinic acid. The medical use of Methylphenidate is for treating attention deficit disorder and narcolepsy though it is also classified by the DEA as a Schedule 2 narcotic, alongside amfetamines and cocaine.

It is extremely rare for a human doping violation to come before the FEI Tribunal – it has not heard any such cases since October 2015. The riders face a minimum two-year ban unless mitigating circumstances are proven.

The FEI has notified WADA (World Anti-Doping Agency) and the United States Anti-Doping Agency (USADA) of the positives.

The riders will remain suspended until the FEI Tribunal renders a decision, unless they successfully apply for the lifting of the provisional suspension and ask for testing of the B sample within 21 days.

No further details are being made available β€œin order to maintain the integrity of the ongoing legal process,” said a FEI spokesman.