The horse’s leg below the fetlock joint is similar to the human finger; the long pastern bone, short pastern bone, and coffin bone are comparable to the three segments of a human finger. The hoof wall is made of the same material as our fingernails–keratin (a type of protein that forms hair, skin, and horny tissue). This specialized, tough shell protects the bones, nerves, blood vessels, and tendons inside the foot.

The hoof horn grows continually to compensate for wear and broken edges, growing down from the corium of the coronary band at the hairline. Just beneath the fringe of hair at the coronary band is the periople, a narrow strip similar to the cuticle on a human fingernail. It is a waxy, varnish-like substance that covers the outer surface of the hoof wall to protect it and prevent excess drying. When footing is soft and wet, the hoof becomes softer. When the ground is dry and hard, the hoof becomes drier and harder and can chip and crack more easily.

The hoof wall is made up of tiny tubules running down from coronary band to the ground, giving some elasticity to the wall so it can compress and expand without splitting. The tubules carry and hold moisture, but have no blood supply or nerves.

On the inside of the hoof wall, tiny leaf-like structures called insensitive laminae interface with sensitive laminae that contain a blood supply and nerve endings.

This interlocking attachment is what anchors the hoof wall to the coffin bone. If this attachment is disrupted by laminitis (inflammation of the laminae), the interface can come apart and the coffin bone might drop at the front or even completely sink within the hoof (founder).

The tough, outer covering at the bottom of the foot consists of the sole, frog, and bars. The latter are a continuation of the hoof wall, serving as braces to keep the heels from contracting. The V-shaped frog in the middle of the sole helps dissipate concussion. The sole a