If the defect (hole) in the part is small enough or the path length for the leak is long enough, it will be almost impossible for the fluids to flow through the hole (leak). The fluid properties that affect flow are pressure, temperature, and viscosity.
Though the answer seems to be correct, but when taken from that perspective, one will not keep focused on the real reason. The main reason why we shoe horses is for work, which then determines the style and the type of shoeing for the individual working horse. Various types of historical horseshoes.
Horseshoes were originally made from iron, which may also account for the superstitions that are associated with this object. Iron was considered magical because it was able to withstand fire and was much stronger than other metals. The superstitions for iron are thought to originate in prehistoric times.