If a horse falls in a race it usually is extremely bad. The rest of the horses will keep running but the horse or horses that have fallen most likely are to badly injured and have to be humanly euthanized. There are some cases where the horses do survive and can be healed but to tell you the truth there aren't many.
it all depends on the race.
any at all
A total of 48 horses will be counted in all four horse race.
Large races like the Kentucky Derby allows 20 horses. The average number for smaller races is 8 to 10 horses.
To compete in a race with Thoroughbred race horses the min age is 16. see: http://www.vrqha.com.au/pdf/Race%20Day%20Regulations.pdf for all the rules and regulations 2008-09
the people in the top box have a sheet with all the names and numbers of the horses
Race horses only have a couple of speeds, fast and faster. During a race the horse uses the fastest gallop he has. Lope, canter or gallop, they are all a three-beat gait.
August 1 in Australia and January 1 in the US and most other parts of the world.
All the races use dressage.
Its ok if all the horses are not being ridden, but they will have to be ridden later.
Usually horses teeth wont fall out, unless the horse is very old, or has had an injury that makes his/her teeth get knocked out. I would say about 30+ years for a horses teeth to just fall out, if they fall out at all.
No, all horses are trained to fall and alot of the scenes are done with special effects.