The successful repair of fractures faces several major problems. Horses often weigh 500kg or more, and the implants necessary to support this weigh do not exist for many bones, and are prohibitively expensive in others. The need for the horse to be immediately weight-bearing after surgery also means that implants must take the full load of the horse for a considerable period of time, and they are prone to fail due to cyclical loading. (This is the same way that a piece of wire can be snapped by repetitive bending back and forth until it snaps).>
One of the biggest problems is that the lower limb of horses has no muscle coverage. This means that the only source of a blood supply is in several large vessels that run down the back of the leg. These are often damaged during the initial injury, and this lack of blood supply can doom any repair to failure. The lack of muscle coverage means that there is only skin to cover the implant, and this limits the thickness of the implant that can be used. Thus even though larger implants could obviously be made to compensate for a horses large weight, the skin could not then be sutured closed over the top of them.
Never-the-less, many fractures in horses can be successfully repaired, and some, such as fractures of the pastern and some cannon fractures are routinely undertaken.