Sheikh Mohammed has been handed a six-month ban from riding in endurance races by the Federation Equestre International.
UK Racing Post reports the suspension comes after his trainer, Abdullah bin Hizaim, admitted to giving his horse, Tahhan, illegal drugs prior to races in Bahrain and Dubai.
Sheikh Mohammed’s wife, Princess Haya of Jordan, is the president of the Federation Equestre International, a vocal opponent of illegal drug use in equine sports.
Sheikh Mohammed alerted authorities to the failed tests in April after an in-house inspection by his staff. He has not taken part in endurance events since the results were discovered, and therefore is eligible to return to competition on October 3.