I've been involved in this game as a fan and as a player for 30 years now, and I've seen this happen a number of times. That doesn't make it easier for me to understand.
In the 6th race at Santa Anita today...the #2 filly, Twistnthenightaway, was loaded in the gate and pretty promptly went down. You could see legs thrashing everywhere underneath the gate. While it's terrifying for us to watch, I can't even imagine what it's like for the poor horse. She was, of course, immediately scratched.
My question to those of you that are involved much more closely than I am is....how on earth does this happen? You have a 16-hand 1000lb animal led into a space that's barely wide enough to accommodate both the horse and the jockey's legs on either side.....how can they fall down? I certainly know that they can get fractious in the gate and all that, but it's just such a confined space that it would logically keep them from falling down.
Like I said, I've seen this happen many times over the years, but I guess this one just prompted me to ask the question...how.
Dumb question maybe, but if you don't know, you ask.