Horseshoes come in various sizes and shapes, and they typically attach to the hoof of a horse with nails that are hammered into the horseshoe and into the hoof wall. These nails hold the horseshoe in place but as the hoof grows, the nails get loose, and the effectiveness of the horseshoe is lost. This happens in average every six weeks. Once the nails become loose, the horseshoes need to be removed, the hoof has to be trimmed, and a new shoe reattached. The exact time between these removal and replacement depends on the type of shoe and the age of the horse.