At my old yard, a lady I knew bought a horse, that cost her an arm and a leg. (£16000, I think that's about $8000) In his younger days he had been quite well known over here for dressage. (cant remember his full name, only his stable name which was jiffy). 17.2hh pure black, beautiful horse.
The only time that poor horse would wee or poo, was if you placed a large bucket in the middle of his stable!
He'd never lived out, and the place he came from was that prim and proper, they trained all horses to do their business in these large tubs/buckets. He lived in 24/7, except for exercise, so of course when he came to us, he didn't go to the loo for a day or two as no one knew he needed a bucket. It wasn't till his owner rang the previous owners, as he was getting so stressed bless him, that we found out. The relief on that poor fella's face!
He eventually stopped relying on the bucket, but it took a good few months. It took him a while to get use to playing out too, he was terrified.
I personally don't understand why he was kept like this with his previous owners. Makes me very sad, such a sweet horse, but he's having a super fun life now.