Sorry if I did not give enough information.
1. This is a knowledgable family, they own many ex race horses, the father is a clerk of the course, the rider 18 years old is an instructor and very savvy.
2 Horse race career was finished, horse given to girl, they get a lot of ex racers so know the procedure. Her father knew the horse was quiet and was a 'looker' so took it as a show hack. They have done this many times.
3. Horse 'turned out' for a rest on pasture - turns yellow for about two weeks, nothing to do with a coat change!!!!!!
4. Horse is brought in for work, is now black and goes of its tree!! Nearly kills the girl, bucks like a bronco, shows no settled manners at all over several days!!
5. Horse is checked for soreness - all OK
6. Horse is brought in again, bucks like a bronco, heads straight for said girl, she jumps out of way, horse ends up smashing a roller door at the horse wash that is how crazy it is.
7. Horse sent to knackery!!! Just too dangerous.
We just want to know what could have been given to this horse to keep it quiet in its racing life, and why the black coat turned yellow for just a couple of weeks once brought off all feeds.