Horses: Dumb Design?

We’re in those few weeks of the year when the ancient and royal “sport” of horse racing bubbles up into public consciousness. That, combined with me wondering recently if I broke my finger playing basketball, has led me to wonder why racehorses have to be euthanized when they break a leg.

There are some unsurprising answers and some surprising ones. The unsurprising ones are that breaks suffered by racehorses can be quite catastrophic, due to the extreme race forces their legs are subjected to. The fractures can result in shattered bones or, as in the case of Eight Belles in last year’s Kentucky Derby, compound fractures that quickly can involve infection due to dirty race track getting into an open wound.

The surprising answers stem from the follow up question “Why can’t they just let them heal?” And sometimes they can. But apparently, horses aren’t great at sitting still, and moreover, adult horses are so bulky that if they lie down for too long, it puts too much pressure on their internal organs. They have to stand, and with a broken leg, their weight is distributed unevenly, leading to a condition (generally in the leg opposite the broken one) called "laminitis." It's basically the destruction of the tissue connecting the hoof to the leg. Once laminitis sets in, that leg is lost and the horse is completely immobilized.

At that point, it's a question of the horse's quality of life, such as it is, and given the rampant anthropomorphism in horse establishment, I think we can safely count on owners not to dispose of horses too cavalierly. (Although there is unquestionably an economic component to euthanasia - if a horse can no longer "produce" for you, and you think you can't even get any stud fees for it, you may not want to waste money keeping the horse alive - something like this looks expensive.)

Is it possible that ancient wild horses pretty much died every time they broke a bone in their lower legs? I guess so, but that's pretty dumb design, especially for an animal that reproduces so rarely (generally one offspring, and gestating in something like eleven months). More likely, domestication - generations of it, designed to make horses (leg breakingly) faster and (organ smushingly) stronger - is to blame here.

UPDATE: Accidentally published too early. I was going to explain/add that I'm not anti-domestication, and that if you have to tolerate a few public horse executions in exchange for powering the past 5,600 years of human civilization, that's a bargain.