Did you ever have any break down?
During a race? Yes. It's a sick feeling. A real old horse named Walted.
I had some who came out of races with career ending injuries. That's a pretty sick feeling too. Most of the horses I trained had problems to start with.
I've had it happen after they've won. Sudden Secret aired at Waterford (called Mountaineer Park now) at 10/1 odds. The track was in terrible shape. Yankee Gunner was the last one. I didn't own him, but he might have been the best horse I ever trained. I was starting to get a few decent owners in my final year. Not exactly people like HH The Aga Khan lining up for me, but I got a few owners with horses that could run.
(Curly haired guy with the porn mustache.)
One breakdown that pissed me off was a horse named Shad Pac. I won four races with her that season. Near the end of the season, her form was tailing off and she wasn't sound at all. I sold her real cheap to someone that said they wanted her as a broodmare and wouldn't ever race her.
I believed them. Look her up on that BRIS CD.
(Shad Pac's only sibling was stakes placed and made over 75k. The dam of Shad Pac won 19 races.)
Instead of waiting a few months to breed to her, they ran her at Beulah Park once and broke her down:

That pissed me off, but I was ring-wise enough to know that it's hard to take any buyer at their word in those days. I had lied plenty of times when I thought it would help me get one bought for the right price.