Simplification or Mystification?

Everywhere you look, everywhere you go, farriers and barefoot specialists alike are talking about “protection” and about balance. Trimmers in particular are tied to the idea of dimensions – there is even a movement that issues little templates to determine the right heel height, or one that issues protractors for getting the toe-angle correct. Hoof mapping is “all the thing” in some quarters.
But not one of these ideas is based on sound scientific knowledge and evidence. On the contrary, most of them define the “mystique” of the horse’s hoof – even given that they are intended to help the owner trim himself.
Hoof mapping is probably the biggest nonsense, but followed very closely by the other two. Hoof mapping tries to determine the position of the P3 and by using a Terry clip to mark the correct outline of the hoof.
Sadly, the horse is not an insect and thus in no way a perfect mirror image – left and right are ALWAYS different as are front and rear. The shape of the hoof is not determined by a Terry clip but by the horse itself; some are longer, some are rounder. Most are absolutely not circular – and never will be however much you trim, since the shape of the hoof is determined by the shape of the P3 inside.The same goes for toe-angles and most definitely for heel height. Nobody can determine what the correct heel height is except the horse.
But probably the biggest mistake made by trimmers and farriers alike, is the supposition that the hoof wall is a weight-bearing structure – it is not! It is the adherence to this historic fable that ensures farriers and trimmers all pay more attention to that what they cannot change than to that what they can. It is impossible to improve the comportment of the horse by dint of adding shoes or by trimming asymmetrically – likewise, striving for an identical height across the heel of a foot is a utopia. None of these actions make the slightest bit of sense.
Why not? Because when we look at the horse’s foot it is static; but a horse uses its feet dynamically. Nobody can show which forces are active under the foot when the horse is in motion; the various experimental systems used all break down at their own functional level. Sensors affixed to the hoof – but carried in a metal structure which not only adds weight to the foot, but also increase limb length and thus altering locomotion; a pad laid in the floor – slightly more reliable but still with the problem that the pad is not a hard structure and thus does not give a completely accurate impression. And who has access to these things anyway – measuring dynamics that change with relation to surface, weight of the horse and even simply the speed at which the horse is travelling at the moment it is monitored?
It is important to realise that the hoof wall is nothing more than a protection for the underlying structures and a touch sensor. It is not designed to carry the weight of the horse and it is even less designed to carry the force of impact when the hoof lands. If we take time to study the shape, form and structure of the hoof from a physics viewpoint we can appreciate this argument much better. The horse is not an insect, there is no exoskeleton – the hoof wall is not a skeletal structure and is not connected to the skeleton. The forces applied during landing, support and departure are not centred on the hoof, not even the three phalanx bones, but rather in the cannon bone. We can draw a line down the cannon bone and see that the actual reception of energy on landing is very clearly in the digital cushion.
So, the hoof wall is simply there to protect the underlying structures, together with acting as a touch sensor. If we remove the hoof wall such that it is not making contact with the ground, we are not affecting the locomotion of the horse – on the contrary, we are helping the horse attain an ideal locomotion. Leaving hoof walls long or trying to “balance” the hoof is counter-productive; we CANNOT balance a hoof – that is a job for each individual horse. Thus the use of all manner of mysterious techniques, trying to determine P3 location and “correct” heel height is all really propagation of a farrier’s fallacy.
Time then to forget the nonsense and approach the subject scientifically. And the basis of all science is physics – biology answers to the laws of physics.

W(h)ither the Peripheral Cushion?

There are giant misunderstandings surrounding horse’s hoofs – even among barefoot practitioners. Vast numbers of trimmers are daily trying to balance off hooves, applying magical mapping templates, doing their best to ensure the heels are at the right height and allowing just the right length of hoof wall to protrude below the sole. They all pay homage to the reference manuals, instruction books, websites and fora that define this, describe that and advise on anything remotely resembling a hoof, be it “good” or “bad” – according to the prevailing wind!

blood vessels of the hoofBut in all this information, a small but key piece of anatomy keeps being overlooked: the peripheral cushion. In fact, you won’t find the peripheral cushion specifically named – it is a “made up” name, albeit accurate, and attributed to Pierre Enoff, the French hoof and locomotion specialist.
There are reams of drawings of hoof cross-sections; and yet not one actually fully depicts the sagittal dissection of a hoof. The peripheral cushion is clearly visible under the tip of the third phalanx (the coffin bone) and is in fact present around the whole of the periphery of the P3 – also being clearly represented in the casts of the circulatory system in the hoof. If we look carefully at Dr C. v. Horst’s now famous cast, we see a thickening up of the vessel structures just under the rim of the P3.

So what is this structure and what should it tell us?

Well, a look at that other well fed area might give us a clue – the digital cushion. As we (should) know, the digital cushion is a tremendously well fed area of the hoof designed to absorb, and retransmit, the impact of landing. It is this area of the hoof that is subjected to upward of 50.000 joules of kinetic energy when the -unshod – horse is in full flight. As anyone who has ever seen athletics and gymnastics will know, we need a very thick cushion to take up the impact of the pole-vaulter when he lands but the floor exercises only demand a thin layer since the landing is from a low height and the gymnast also needs to have sufficient purchase to make her/his figures.

We can thus conclude that this area is not intended to receive an impact of any great intensity whereas the digital cushion is. It is therefore of tremendous consternation that we see just where the impact of landing is concentrated in the shod horse. The digital cushion is rendered to all intents and purposes ineffectual – it cannot contact the ground and, if it should, it is not acting as a cushion but rather as suspended elastic which is not its design ethic.

Heel meter

Example of a heel template

It is basic mechanics but it is ignored by so many, owners, farriers, vets and, sadly, even a large number of barefoot specialists. Even among the last group, there are still many tied to the idea that the hoof wall is part of the weight bearing structure. They will try and “balance” the hoof to make sure there is even contact around the hoof wall, or try applying templates to “get the height right”. Pete Ramey states that the hoof wall should protrude about 1/16″ (about 1.6mm) below the level of the sole. Aside of the conceived ability to be so accurate, this is the application of the flawed insights of the farrier.

These insights are often also perpetuated by the equine specialists in the veterinary world. A reason for many people to point to these techniques as being “right” despite the majority of vets having only very restricted mechanical knowledge. Typically, the specialist clinics treating laminitis will suggest the application of special orthopædic shoes to support the hoof. When we realise that the susceptible, loose, laminitic hoof wall is now being used as the support point to aid healing, we cannot help but wonder about the teachings of veterinary colleges and farriers’ schools.