Understanding the mechanics of the hoof
The hoof wall grows down from coronary band and has a vertical grain [hoof horn] This is wrapped around pedal bone to the heels. It turns at the heels [heel buttress] and continues forward each side of the frog to become the bars. This is a continuous little wall, which forms the hoof capsule.
The entire hoof wall is attached to the p3 [pedal bone] by the laminae. This is a two part organ, like velcro. The outer [insensative] laminae is attached to the inner hoof wall, and grows all the way to the ground and gets worn or cut with the hoof wall. The inner [sensitive] laminae [blood filled] is attached to the bone and interlocked with the insensitive laminae.
The sensitive laminae, also grows down with the insenensitive laminae -but stops at the bottom of the bone. In it’s place it sends down a material we call the white line. Therefore the depth of the white line is the depth of the sole.
The sole grows in horizontal layers, as does the frog. These are not attached to the underside of the bone by laminae, as the attachment need not be so strong.
Sole and frog grow from a blood filled corium. The bars are hoof wall under tension to hold the capsule from bursting outward.
When a hoof is contracted and there is no outward pressure, the bars can become bent. The digital cushion is a sponge like material, which stores the arterial blood pumped by the heart to the foot. Under load the entire solar foot spreads and deflects down, this action forces pastern bones down onto the digital cushion - the ground in turn pushes up through the frog and digital cushion, this squashes the digital cushion and forces blood through the lateral cartilages, p3 and the laminae.
If this is restricted in any way, you have restricted blood supply, leading to poor quality unhealthy foot. The foot will also drop in temperature and become numb, this will give the impression that the hoof is now tougher etc, BUT in fact the horse can’t feel his feet, as it has an anaesthetic effect. Sometimes when the hoof is liberated the return of all functions can cause temporary pain.
In hard frost, shoes and nails freeze and so does the moisture in the nail holes.
The properties of steel do not unfortunately conform to the action of the foot.
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Illustrating damage on hind foot. After removal of shoe the unhealthy state of hoof is clearly visable! Please click on images to enlarge.
 Another damaged hoof.
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