A quick Google search shows a number of accusations of poisoning horses: https://www.espn.com/moresports/news/2003/0709/1578661.html https://www.espn.com/moresp

A quick Google search shows a number of accusations of poisoning horses: https://www.espn.com/moresports/news/2003/0709/1578661.html https://www.espn.com/moresports/news/2003/0709/1578661.html https://www.telegraph.co.uk/news/2019/06/21/dressage-poisoning-scandal-horseowner-alleges-stallion-targeted/ https://www.telegraph.co.uk/news/2019/06/21/dressage-poisoni... Plus apparently a huge amount of drugs given to their own horses trying to cheat.