I happen to support horse slaughter in the US for all the reasons Bubba has listed.
Stopping slaughter won't stop abuse. I think abuse will increase, quite truthfully. Already there are reports of people turning unwanted animals loose. The animal shelters will soon be full of horses, just like cats and dogs. And where then do they go? They're euthanized and sent to a rendering plant and turned into cat and dog food. Why is it okay for cats and dogs to eat them, but not people?
Here in the western US, the wild horse herds run the risk of being 'invaded' by domestics that people will undoubtedly turn out. In turn, that will cause greater stress on the environment and more tax payer dollars to support them. Which I find rather ironic, as Senator Burns from Montana slipped his little rider in which would have enabled wild horses to be sent to slaughter. It caused such an uproar (and he was voted out of office) that the wild horse community is largely supporting the ban on slaughter in an effort to save the mustangs. Now Mr. Burns will have twice as many horses to contend with should the ban pass.
No, the solution is more independently owned slaughter houses instead of banning them. Like I bring the lambs to, or the pigs. Places where you know things will be done swiftly and correctly, with little stress to the animal. It's unfortunate that it costs so much to euthanize a horse. At least sending an old one to become burger will be a swift end and feed a hungry mouth.
Baby horse shoes? I'd say it was unlikely, but then again, perhaps it was a PMU foal? Never know what some twisted folks are doing out there (not illegal to turn horses into clothing, is it?)