What was the biggest scandal in equestrian sports?

In Sweden, the multiple winner of the race – a stallion named Propalshn – was stripped of all his regalia. It turned out that the secret of his success was in a special operation, in fact, in doping. Now the owners of the horse will have to return not only the awards but also tens of millions of crowns in prize money.
A special operation was carried out in America before being sent to Europe. This is legal in the United States, and American horse traders claimed to have notified the Swedish Tribal Association in writing prior to sending the animal overseas. The letter really exists, only for the time being, for some reason, no one paid attention to it. The horse’s coach Danielle Radan said he hadn’t known about denervation.
Deprived of all the regalia and prizes won in Sweden, the stallion returned home to the USA, where he will work there as a producer. By the way, Swedish breeders refused to issue documents to foals received from a fake champion. In other countries, this decision was not supported – Propalshn was approved for breeding in Norway, Belgium, Denmark, Finland, the Netherlands, Germany, and Italy. And in France they decided not to deprive the horse of titles at all.

Source: horseracingsweden.com