“Iron and fire”: history and advances of mule shoeing
During the last decades in Europe and the United States there has been a renewed interest in the use of the mule. This review summarizes the scarce information available in the veterinary literature on the anatomical particularities and shoeing techniques of the mule’s hoof that have an important impact on the health and welfare of the animal. Compared with the horse the mule’s hoof has a distinctive upright dorsal wall angle and a broken forward hoof-pastern axis; the cartilages of the distal phalanx are much more developed towards the palmar/plantar parts of the hoof; the inclination degree of the hoof wall to the ground, at the toe, the quarters and heels is almost vertical; the sole has elevated moisture content in its deep layers and the horn tubules are more evident; the coronary dermis together with the large coronary groove are higher; the laminar dermis of the wall segment is less extended; the mule’s hoof is smaller, longer and narrower. The mule’s shoes display a web of greater and uniform thickness over their entire extension compared to the horse’s. The toe of the front shoe is rounded, fitted slightly wider and turned up; and its outline fitting is marginally wider on the toe and on the external branch. The front shoe coverage, therefore, is slightly wider at the toe, and gently decreases to the toe quarters, heel quarters and heels; moreover, the internal branch is narrower than the outside. The hind shoe shows the same characteristics of the front one, plus some distinct features such as a larger blunt toe, equal full outline fitting proportions, and identical branch coverage.