[sweetwater]

My sister works at an equine facility (university veterinary hospital) and the vets maintain that humans trying to breed a faster horse have compromised the animal's basic structure, particularly skeletal development. Combine that with heavy training, running while carrying weight, and their immaturity spells doom for some of those animals.

Of course, the vets generally only see horses that are harmed by racing, but I tend to believe that they are sincerely concerned.