In a statement released by the FEI:

The Canadian horse Victor, ridden by Tiffany Foster, has been disqualified under the FEI’s hypersensitivtiy protocol due to an area of clear and obvious hypersensitivity on the front of the left forelimb.

The Veterinary Commisson have stated that the horse has an area of inflammation and sensitivity on the left forelimb just above the hoof. There is no accusation of malpractice, but the horse has been deemed unfit to compete by the Ground Jury.

The Canadians have filed a protest, but a decision by the Ground Jury on hypersensitivity is not appealable.