horseshoe
Curved metal band nailed under the wall of the hoof to protect it against wear, to absorb shocks and to provide better traction on the ground.
nail 
Pointy metal pin; its head lodges in the nail hole to attach the horseshoe to the hoof.
branch 
Each of the two parts of the horseshoe starting at the toe and ending at the heel.
nail hole 
Rectangular opening made in the iron to hold the head of a nail; there are usually six to eight nail holes.
heel 
Terminal end of each branch of a horseshoe; it is rounded and beveled to prevent injury.