Research has shown that the Norwegian rider Johan-Sebastian Gulliksen is not guilty of using doping with his horse Arakorn (f. Cantos). The horse got a positive doping test last year and because of that the FEI decided to suspend Gulliksen until they had more information about the substance that caused the positive test. The substance causing the positive test was democolocine, used in medicines against cancer. It however looks like the substance came from contaminated hay that Gulliksen gave his horse.
The substance is known for sometimes showing up in hay.