The hoof mechanism and how it works.
A conditioned barefooted horse’s action is effortless and glides over all terrain with ease, extending so the impact is minimal from heel to toe like a tire rolling over the ground. In this way, it is very fluid and has no peek impact. The hoof mechanism aids optimal blood flow and helps the heart in its function. As the weight of a horse descends, the back of the foot expands, causing a flexing of the hoof wall and as the hoof lifts off the ground it snaps back into place. The flexing draws blood into the hoof and the snapping shoots it back up the leg like a hydraulic system.
Dr Bowker discovered that blood doesn’t only provide nutrients to the foot, in conjunction with the digital cushion it also helps with shock absorption. The hoof mechanism draws blood from under the coffin bone into the digital cushion and the blood works like the gel does in training shoes dissipating energy.
As the bulbs, frog, and the heels flex on the initial impact the slowing down of a horse’s weight into the foot ‘the braking’ is performed by the digital cushion. The lateral cartilages are designed to absorb some of the impact as well and after the descent has been slowed down the actual stop is performed by the bars, it then dissipates this energy into the lateral cartilages.
The suspensory apparatus which supports the fetlock joint acts like a sling preventing hyperextension and limiting palmar flexion. However, a little-known fact is a conditioned barefooted horse with a well formed back of the foot also acts as a stopper. The digital cushion not only helps to stop ligaments and tendons from over stretching but also cushions the descent of the fetlock. Wow, now we see how important this mechanism and its development is and how any interference with its function will be detrimental to a horse’s performance.
Effects of shoeing on the hoof mechanism:
Shoes affect the hoof mechanism in several ways. They stop the hoof mechanism from working correctly by restricting hoof expansion and lifting the frog off the ground. Thus restricting blood flow in and out of the hoof and this causes poor quality hoof horn and puts extra strain on the heart especially during exercise. Shoes also have an anaesthetising effect on the foot caused by this restrictive blood flow, so when a shoe has been removed the damage caused by shoeing will leave the hoof more often than not tender and sore and the horse will feel this tenderness as the blood flow returns. Shoes also cause contraction which also stops the hoof mechanism from working correctly. Quarter cracks are common in shod horses and not in barefoot horses. This is because the hoof expands all the way to the front of the hoof, so if the front half is held rigid by a horseshoe using three nails each side and the back tries to expand then stress will be applied at the quarters. If a fourth nail is used in the shoe this will stop most if not all the expansion in the back of the hoof and the crack will appear further back towards the heel.
© Copyright 2015 Chris Simpson