I hadn't thought of it before, but when our horses get their feet trimmed, the dogs (a 100lb Shepherd and a smaller Shepherd mix) love to gnaw on the trimmings. Hoof trimmings are basically really thick fingernails.
They'll gnaw on them for hours. Wonder if there would be a market for it.
Dogs will eat anything. One of my GSD's almost died after eating about a third of a blanket. His xray looked down-right scary, with this ball in his stomach. We were very close to having to have surgery to cut him open to remove it (which would have been very dangerous and very expensive). Somehow he managed to vomit the thing out in large chunks. We all dodged a bullet on that one.
So, yeah, it doesn't surprise me that they would eat horse hoof trimmings.
If you were to productize something like that you'd have to make sure you run through some testing to ensure dogs won't be harmed. The product liability element in products that people and pets eat should not be ignored, particularly in a litigious society like the US.
They'll gnaw on them for hours. Wonder if there would be a market for it.