Irish trainer Gordon Elliott faces a disciplinary hearing on Wednesday over a positive drugs test for one of his horses at last year's Cheltenham Festival.
Zanahiyr finished third behind Honeysuckle in the Champion Hurdle.
But the horse tested positive post-race for 3-hydroxylidocaine and could now be disqualified.
The substance, a metabolite of Lidocaine, is often used in racing stables as a local anaesthetic.
Elliott will face an independent panel after the case was referred by the British Horseracing Authority.