German dressage rider Isabell Werth, a three-time Olympic gold-medal winner, was suspended by the FEI after her horse Whisper, owned by Madeleine Winter-Schulze, tested positive for the antipsychotic drug fluphenazine. The sample was taken at a show in Weisbaden, Germany, on May 30, 2009.
The vast majority of upper-level competitors obey doping laws, but this positive turns up occasionally as it is a long-acting tranquilizer effective at extremely low doses. The effects may last for four to six weeks. There is no legitimate medical use of this drug when sedating horses for routine procedures.
The drug has been used to sedate horses on prolonged stall rest, but there are multiple reports of severe, potentially fatal, side effects involving the nervous system.