I don't consider horse racing to be abuse in and of itself.
I love animals of all sorts, particularly dogs and horses. I have since I was a wee tyke and I don't expect it will change in my lifetime. I don't anthropomorphise them, I admire them as they are.
My family has a dear friend; a woman who's been like a second mother to my brothers and me. Her family has been involved in Thoroughbred Horseracing for 3 generations. I assure you, they're not rich. From my experience with horseracing through these people I know that horses involved in racing are not tortured, beaten, starved, inbred, poisoned, drugged or made to behave in ways they're unhappy about.
The horses I've known have the same types of individual personalities as do many dogs and cats and human toddlers. They may lack the power of speech, but the do make their delights, fears and irritations known. I've never seen a horse cringe from a crop. They respond to them as though they weren't even there. But I do know that the horses want to run, just like I know that dogs want to poke their heads out the window of a moving car. (You possibly don't want to know the injury and euthanasia statistics on dogs injured doing this. I'm sure many would feel it abuse then, as well.)
The comparisons to cockfighting, dogfighting and the like are failed analogies to my thinking. In such spectacles as cockfighting and dogfighting, every animal who is engaged in the contest will be injured, probably maimed and one will likely die. I understand that the potential in horseracing is that 1 in a thousand race horses starting a race will sustain a life-threatening injury, and that is heartbreaking and appalling. It is however, nothing like the patently abusive statistics of cockfighting and the like. Further, it should be noted that the probabilities for a non-racing horse to sustain a life threatening injury is not substantially less.
The difficulty isn't with the Thoroughbred's speed, it's with the design of the horse. All horses, even the meaty Clydesdale are thousand-plus pound beasts on ankles not susbstatially larger than a human being's. And unfortunately, to heal an injury, a horse must stand on the injury.
Veterinary science has made great strides in it's ability to treat a horse's injury, in large part because of the vast sums of money put into equine medicine from the racing industry.
Contrary to your assertions, Polytrack is already making huge inroads in reducing stress fracture injuries and the severity of other types of injury in racing and is now mandatory in several states.
I very much respect the beliefs of those who feel this is abuse. I know they care about the beasties and that warms my heart. I just don't happen to agree that it's abusive to give a horse a safer, controlled forum for doing what horses do.
I have a friend who is a marine biologist specialising in Orca. We often bet amoungst ourselves as to which male Orcas will be selected for mating by a female. I don't consider that abuse either. Though, I do wish we made the waters of the world a bit safer and cleaner.
Peace. This is the last I'll say of this issue. Those who've attempted to *koff* persuade... me have employed some fairly ineffective techniques and while I appreciate emotional arguments more than most, I feel them not conducive to discussion.
I wish all those with a care for the creatures of the world the very best.