Looks like it's for a front foot, and has caulks that were probably for ice traction, seem to be a bit thin for ordinary caulks used for traction on farm animals. There
are a number of reasons to use a bar shoe, such as correcting a foot problem or protecting the heels or helping to heal a foot disorder, or the foot -- hoof wall -- is
broken up and the farrier is unable to get enough sound nails. The rust makes it look like an early version, otherwise nothing different is happening to a horses hoof
that hasn't happened for centuries, and that style of shoe is being nailed on a horse somewhere every day. It's very difficult to say a horse shoe is from a time period
by looking at it. The best way to date a horse shoe is to find it in conjunction with other identifiable relics from that same site.