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 orthop├Ždic 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.

What does the vet know?

It’s worrying, but how often do vets actually know what they are talking about when it comes to hoofs and feed?
Most veterinary colleges are geared up to small animal and/or livestock work these days and the specific equine knowledge is still rooted firmly in the late 19th / early 20th century. True, we have a vast range of antibiotics, anti-inflammatories and pain killers these days but even those are often applied in a surprisingly unscientific way.
Only this week, I came across a horse which, according to the vet, had been trimmed (by a regular farrier) too short… There rests the first question, what is too short? If you mean the sole has been cut away, yes, but trimming back to sole level is not “short”. Prescribing Phenylbutazone (bute), he showed even less knowledge – you cannot relieve contact discomfort with an anti-inflammatory.
Furthermore he prescribed avoidance of hard ground for at least 4 weeks and soaking in soda at least twice a day. What a horse needs in these circumstances is quite the opposite – movement will stimulate the regrowth of the hoof and also harden off the soft sole tissue that is so sensitive. Soda will only keep this tissue soft and sensitive.
In this case, the owner believes implicitly in the vet (and the farrier is no longer welcome!) who has now changed his advice… Because the horse was refusing to leave his stall yesterday (banged up for 14 hours) the vet came and looked him over again and decided it was equine exertional rhabdomyolysis (ER), also known as azoturia or Monday Morning Disease. The treatment for this is vitamin E and plenty of movement.
I don’t blame the vet for changing his advice but it does rather make a mockery of his first diagnosis and treatment…
What this all boils down to is don’t just believe every word your vet says. He is not an expert in every field of veterinary medicine and furthermore, his horse-related education is very restricted. If your horse has problems after trimming, call the trimmer first. He probably knows as much about horses feet as all the local vets put together. If you use a traditional farrier, at least give him a chance to come and see for himself what has happened (the training for farriers, not dissimilar from that of vets, also sadly remains stuck in the early 20th century).