If it helps, bear in mind that Eight Belles was not in pain. This happened as she was slowing after the race, like IMMEDIATELY after running 40 miles an hour amongst 19 other horses crowding for position. She was still on an adrenaline high. When she broke her ankles, she most likely didn't feel it, and she was put down immediately so adrenaline didn't have time to fade and pain to kick in.
There are problems with the sport, mostly centered around breeding. Eight Belles in point, her sire is Unbridled Song. Hardly any of his foals made it past 7 races (Eight Belles was running her 10th race). They eventually sprain an ankle, break a cannon bone, pop a splint, get quarter cracks or foot bruises, and before you can say "and they're off!", the horse is off to the breeding shed, retired because he "has nothing further to prove." Which is a joke, btw. A win in one stakes race. Apparantly that's all it takes before a classy horse gets shipped off to breed more unsound horses. "Veterans" these days haven't run more than 10 races, when in the past, they'd run 10 in one year (and in the old days, like from the 60's and earlier, they'd run the 10 races, maybe 20, in a short span and then take a rest. They'd run a race, rest for 3 days, run another race, rest for 2 days, run another, rest for 5 days, run another, and so on and so forth until winter and they'd spend the next season or two just frolicking in the fields and growing). There's a theory going around, that I agree with, that the reason horses these days are so unsound is because they don't actually WORK. They do nothing but train, and then race every 2-3 months. It doesn't strengthen the horse; on the contrary, it weakens the bones because they're not being used. It certainly does fit when you think back on the horses of old.
On the plus side, I can't think of a single racing fan who doesn't love Curlin, because he's now 4 and he's STILL racing. He just won the Dubai World Cup a couple of months ago, and most owners would have retired him after he finished 2nd in the Belmont last year. And even more would have retired him after his win in the Dubai World Cup (it's THE international place to be for dirt horses), but nope, he's slated to run in the Stephen Foster in a couple of months, and he's going to continue running this year. We need more horses like him in the sport. And when he eventually retires, he'll be an asset to the breed, as he'll add in some longevity and soundness. Horses like Unbridled Song and Storm Cat and AP Indy should be banned from the breeding shed. But even though their foals race so little in so short a time before getting injured (and being whisked to safety to breed more unsound foals), their foals show absolute brilliance, so people just keep breeding to these stallions.
In the Ruffian: Burning From The Start book, there was a quote that's soooo true. It says that fast horses always get hurt. The slow ones don't run hard enough to do themselves any harm. On that Ruffian note, her trainer, Frank Whitely, died on Friday at the age of 93. He was one of the great trainers, and not because of the great horses he trained. It was the WAY he trained them. Grass and oats. He didn't rely on drugs, only used the vet's assistance when necessary, stuck with one farrier who had proven his worth, iced his horses legs every day (even though they weren't hurt), etc. He was one of the great ones, and even though he's been retired for a long time, we've lost a great trainer.