Top British show jumper Michael Whitaker has been found guilty of inadvertently doping his stallion Tackeray with the female hormone altrenogest after a mix up with feed buckets at La Baule.

He has been banned from competition for four months and fined CHF 200 (£125). Because Michael has been suspended since May he will be eligible to jump again on 25 October.

Tackeray tested positive for the prohibited substance at the Nations Cup competition in La Baule, France on 15 May.

The International Equestrian Federation (FEI) published the result of the disciplinary case today (24 September).

The FEI tribunal found that Michael had been “negligent” and was responsible for a mistake which led to the stallion being fed food laced with altrenogest, which is found in the product Regu-mate.

Mares are allowed to be treated with altrenogest at competitions, and Michael has applied in the past for his female rides to receive the medication.

In a statement his groom Cynthia Gurrie told the tribunal that she did not remember mixing up the feeds but it was the only explanation for the positive test.

“It seems inevitable that I either failed to wash the buckets properly or that I gave the wrong feed to the wrong horse on the first day or so that I arrived at the show,” she said.

She explained to the FEI tribunal at a disciplinary hearing in London on 11 September that she had a very tiring journey to the show as because of a storm in the Channel the ferry was cancelled. She no longer works for Michael.

Michael had asserted that the case should be downgraded to medication but this was not accepted the tribunal.

The ban meant Michael was not available for the European Show Jumping Championships at Windsor last month on GB Nations Cup teams.

See next week’s Horse & Hound for more on this story.