Northern Ireland showjumper Jessica Kurten has confirmed that one of her top horses has tested positive for a banned substance.
Ireland's Jessica Kurten is ranked number four in the world
The world number four from Cullybackey said she had not given the mare, Castle Forbes Maike, anything.
The positive sample was taken at the Longines Grand Prix in La Baule in May where Kurten rode Castle Forbes Maike to success in the £100,000 event.
If the B sample is also positive, the case is likely to go to a tribunal.
Kurten could face punishment from the International Equestrian Federation, including suspension and the loss of prizemoney from La Baule.
"There is a positive dope test but there is absolutely nothing to ground this. I did not give the horse anything," Kurten told the Irish Times newspaper.
On Friday, Kurten qualified for Sunday's individual final in Mannheim, Germany, while partnering Castle Forbes Libertina.