The case involved the horse Castlebar Contraband, ridden by Sheik Abdul at the CE1* in Fontainebleau, France, on Oct. 15, 2016.

Castlebar Contraband suffered an open fracture to its front right cannon bone during the event and had to be euthanized. Blood samples collected from the horse post mortem revealed the presence of the controlled medication substance xylazine, which is used as a sedative, analgesic and muscle relaxant but is prohibited in competition. The substance, which is rapidly excreted from the body, is known to be used in endurance to lower the heart rate. No valid veterinary form, the equine equivalent of a therapeutic use exemption, exists for this substance.

Source: Chronicle of the horse