But Eight Belles was a tragic manifestation of a problem that is more pronounced every year. America's breeding industry is producing increasingly fragile thoroughbreds. They may not break down, but they have shorter and shorter racing careers before going to stud to beget even more fragile offspring.
The facts are irrefutable. In 1960, the average U.S. racehorse made 11.3 starts per year. The number has fallen almost every year, and now the average U.S. thoroughbred races a mere 6.3 times per year. Almost every trainer whose career spans the decades will acknowledge that thoroughbreds aren't as robust as they used to be.
There are at least two good explanations for this phenomenon. In earlier eras, most people bred horses in order to race them, and they had a stake in the animals' soundness. By contrast, modern commercial breeders produce horses in order to sell them, and if those horses are unsound, they become somebody else's problem. Because buyers want horses with speed, breeders have filled the thoroughbred species with the genes of fast but unsound horses.
As this change in the breeding world took place, the sport was allowing the use of pain-killers and other medications that are forbidden in most other countries. They allow infirm horses to achieve success, go to stud and pass on their infirmities to the next generation.