Ok massi. - there is an awful lot of drivel and misinformation put out by the anti-horse racing crew and this is one of them. Horses have always had to be "put down"since the year dot if they fall and break their legs, esp. the front ones.
Actually, one of the positives of horse racing is that funding is being made to see if they can alleviate this situation through horse-medical research......surprisingly, says he ironically, just like any horse owner, it hurts like mad when a horse has to be put down - the owner, the trainer, the jockeys, the stable boys. You don't want to be around a stable when it has happened.