If a horse has been receiving any kind of treatment for the hooves, such as thrush solutions, the hoof should be kept away from dogs. Those medications are often toxic if ingested by a canine.
Large pieces of trimmed hoof and small dogs are not a good combination. A greedy dog could easily over-eat on a stable’s worth of hoof trimmings. Think Corgi here!
Remember that horse hooves are walking around in manure. If you have dewormed shortly before a farrier visit with any ivermectin product, the hoof trimmings could be contaminated with manure containing some ivermectin. Ivermectin can be toxic to many breeds of dogs (see January 2012).
Hard, brittle hoof trimmings are not safe for dogs. Just like brittle cooked bones, they can splinter internally, crack teeth and cause intestinal damage.
If you feel your dog needs (basically wants) some hoof, limit it to fresh trimmings and small pieces. Then clean up all the rest of the trimmings and dispose of them safely where your dogs can’t get to them.
Deb M. Eldredge, DVM, Contributing Veterinary Editor