Actually, there is an article by a VERY well-known vet that talks about the actual science behind how work DOES strengthen bones in race horses. If I can find it, I will post it.
I know this is an older thread with a couple newer posts, but I'll add to in anyway. Horses break down at the track, just like horses break down in OTHER horse disciplines. It happens...it goes with the territory. Do I like to see break downs? No, of course not. I'm an avid horse race fan and handicapper, I go to the track alot and have yet to see a break down. People get up in arms when they see it on live TV, when it's a daily occurence in the general horse industry. A friend of mine who kept her show horse at my trainer's, a really nice WP paint mare....paint mare was turned out in the indoor due to inclement weather, she was racing around feeling good...took a bad step and broke her ankle. It happens.
Another case in point is Hickstead, he died immediately after a jump round in Canada, just recently. He had a heart attack, and dropped to the ground....the stands full of people. It's sad, but it happens. These horses are athletes but they are not infallible.
Of course accidents happen, in every sport, at every age. However, not only are we talking about breakdowns necessarily. Thoroughbreds off the track can have a miriad of problems, due to their joints and other parts of their bodies not being developed. I have many problems with the racing industry, but I do not think it wise to go into that.
YES horses die, accidents happen, and they get hurt. However, racing a 2 year old, in my opinion, is like riding a motorcycle at 180 on a busy Chicago highway at rush hour. You're asking for it. You could easily say accidents happen in Chicago, every day in fact. Do people still commute every day? Yes. Do people still get hurt? Yes. BUT that does not mean you should push it by being the one on the motorcycle. I see racing in the same light. Why push it?
I would love to see the article though. It sounds like an interesting read.