Yes, race horses, polo ponies, and show jumpers die in training, and on the job. It's sad to see, and sadder still to witness directly. As a former polo player and stable employee. I saw several horses die, some from heart failure, some as the result of fractured legs. I had a horse which, from time to time, had to use pain-blocking medication in order to be able to play polo. There were other horses which were fine animals, yet a bit small for their riders, who succumbed to over-use in hot weather, and died of heart failure. Eventually, my horse, given to me for Christmas by my employer, had minor surgery on his forelegs to remove broken splint bones. His pain thereby relieved, we continued to play polo for years. Horses, by nature, are more fragile than we like to admit. They spend their lives walking and running, on the equivalent of their middle finger nails, pounding the ground, piston-like, on narrow legs, with complex bone. tendon, and ligament structures. The horses in the Triple Crown series are babies- three years old - and most live long, healthy lives. I personally played polo on horse that had been played for 20 years before being "retired" to riding classes. They were beautiful, affectionate, and hard-working animals, but horses are not pets. They are working animals, sometimes engaged in strenuous or even dangerous activities. Yes, they live, work, and die, sometimes needlessly. That's no reason to ban racing. That's another reason to train and use them lovingly and ethically. Horse racing is heavily regulated, as are equine sports in general, and unethical owners, rider, grooms, and trainers can quickly get not only bad reputations, but can also be driven out of the business by their peers.