February, 2022 -

Buttress~Heel~Switchback

A Buttress by any other name…
https://www.thoughtco.com/what-is-a-flying-buttress-4049089

The hoof as a whole is an amazing mechanism that is perfectly suited to it’s purpose. Everything on this earth that grows naturally has been engineered to it’s current form by the forces around it, and so, can be thought of using the terms of engineering. https://simplicable.com/new/material-strength

The buttress (and bar) structures serve as the lynch pin of the hoof.

Turns out, ‘lynchpin’ is very similar in meaning as ‘buttress’. Who knew…

This is not yet an optimal buttress, but it’s getting there. Note the laminar line is still a bit pointed. Note the increase in bulk.

Picture a hoof capsule without a buttress. It wouldn’t work. It doesn’t work.
When buttresses are compromised, the hoof is compromised. Full stop. Compromised being less than optimal.

And optimal buttress is more than the sum of it’s parts. Literally.

Buttress mass = Wall mass + Bar mass + (X)

But it’s more than just that. This fortified structures hold their respective heel walls and bars at a specific angle to one another. From each buttress, the bars point back into toward the center of the capsule, to the toe quarter on the side opposite. The buttress is pointed at its outside, posterior end and the yellow laminar line makes a graceful arch around it’s interior edge.

But here’s the thing . . . It’s not always easy to see when a hoof has a compromised buttress. But, there are some tell tale signs specific to buttresses not yet being all they can be, and that there may be an issue, bearing in mind that each foot distorts in ways specific and peculiar to their own internal weaknesses and external conditions:

Thin bars ~ Thin bars can happen when the hoof is run forward from behind.

Laid over bars/bars that wont ‘stand up’ ~ Bars stand up only by virtue of their solid attachment to the buttress structure, so if they’re not solidly attached, or if the buttress structure is no longer there, the bars by virtue of the horses weight and ground forces, can only lay over.

Cracks where bar ‘joins’ buttress ~ But when there’s a crack, that’s a sign that the bar is no longer joined to the buttress. This show up as a buttress is getting trimmed out of the foot, or as the foot is being rehabbed.

Bar abutting buttress further up the wall ~ This is the next step after a bar crack. First there’s a small dis-attachment between the bar and buttress. Then, in some feet, as the frog structures get pulled forward, the bars get pushed along forward in front of it.

Curves ~ Curved bars are a sign that the back of the foot will expand when trimmed in a way that will allow for this.

Kinks at the buttress end of bars ~ Kinks at the buttress end of bars are what happens mid way between curved bars and a dis-attached bar that is heading up the solar surface of the foot.

*Some examples below were found on the internet, not sure whom to credit.

Thin, curved bar. An optimal bar will be a bit more robust than this.

Kinks where bars become buttress. Bars look thin as well.

Bar kinks at buttress. Crack between bar and buttress. Bar also looks of different material than buttress where the bar currently butts up against the buttress-yellow arrow. Notice how the bar is grey and the wall a dun color. If you were to push the bar down along the wall to where the red dots would run in a straight line, the grey of the bar would match up with the grey of the caudal end of the wall there.

Buttress on left is scant in size with crack. Crack at bar/buttress meeting on right.

Distinct kink where bar and buttress meet. Crack started too. Bars curve before they kink when the back of the foot is being drawn down and forward.

Bar migrating up the inside of the wall. Bar outlined in red dots. Wall outlined in blue.

The Hoof As A Pump~Does the horse really have four hearts?

Do the hooves really serve as additional hearts? Is the frog a pump?

I’ve read recently in Pollitt’s book, that the veins in the horses hoof do not have valves to stop back flow as other veins do. If this is really the case, it highlights just how important movement is to the health of the horse. It is movement that unloads and loads the foot, and it is this loading and unloading that serves as the dynamic pumping action of the foot. Without movement, there is risk of stagnation.

I’ve read more than once the frog described as a pump. The importance of a beefy frog with ground contact upon weight bearing being the hallmark of desirable, which to me meant that others were thinking of the frog as a push pump. What I understand of biology is in line with the concept of the foot serving as a pump. But what I know about engineering showed me that it’s not that the frog is a ‘push pump’ so much as it is the whole mechanism of the hoof that works as a bellows pump, and the frog serves as the bellows proper.

A perfect Bellows Mechanism.
White-Bars, Aqua-frog wall, Blue-Central Sulcus Wall

Moving from the left to the right: the bar, outside frog wall, central sulcus wall x 2, outside frog wall, and bar wall all work together to form the bellows.

The wall, serves as the spring mechanism upon which the expansion and contractions of the foot acts, and that returns the expanded bellows to it’s un-expanded state, when pressure is released. When the foot is weighted, both the bellows and the wall expand. When the foot is unweighted, both the bellows and the wall contract. The degree of movement is nil at the toe, directly opposite the caudal foot, and increases in amount to where it is is largest, across the heel end of the frog.

Comme ca.
Don’t @ me. Desperate times call for desperate mock-ups.
1&8-wall/spring mechanism, 2&7-bar, 3&6-frog wall, 4&5-central sulcus wall

As you ponder these things, imagine what goes on inside a foot when a static shoe is nailed on to the expansion spring while the mechanism is non weight bearing, and so, contracted. Then imagine what happens to the forces put on that now fixed structure when is is weighted.

The Hoof Capsule

Moving around the capsule…

The hoof capsule is made up of the same constituent as our hair. This was recently brought home to me at a farrier convention while a horse was being hot shod. The smell of burning hair is too distinct to not recognize. The capsule is made up of tubules that are born and grow down from the coronary papillae, and fused together by an exudate.

The capsule includes the outside wall, buttresses, and bars.

The hoof tubules are longest at the toe, getting shorter and shorter as they round the foot toward the buttress. The wall capsule makes an acute turn at the buttress, and continues back toward the toe-quarter on the opposite side of the foot. The wall tubules continue to shorten toward the natural terminus of the bar, about half way up the frog.

Looking through the hoof capsule…

The outer layer is made up of hard, pigmented tubules. Inside this is a non-pigmented layer of tubules that are softer. And on the inside of this layer, are the insensitive laminae. These three layers make up the wall of the hoof capsule. On the sole plane, the wall is joined to the sole at the white line by the exudate of the terminal papilae of the sensitive lamina on the inner hoof. This exudate is most often referred to as the white line, though it’s yellow.

To map or not to map?

I’ve tried it. I’ve watched others map a foot while listening to their explanations for why they are doing what they are doing; different styles, explanations and thought processes. None of them were convincing enough to leave me confident that they were pit-fall-free. There were just too many slippery slopes. Too much about mapping is arbitrary. Some still, small voice in me said there was a way to see a hoof that was both more simple, and more clear, and would apply to all hooves.

Meanwhile, different aspects of the foot rattled around in my head. All parts of the puzzle. Sorting things out, one by one, bars, buttresses, central sulcuses, when finally…this photo crossed my path as if in answer, and the whole thing clicked.

Seeing this photo was the penny-drop moment for me. One glance at the picture below and I realized that an optimal frog is the hallmark of a healthy, balanced foot. This is a photo of the healthiest, most perfect frog I have ever laid eyes on. Complete with frog curtain.

The state of the frog reveals the state of the hoof. And an optimal frog looks a certain way.

The frog IS the map.

An optimal, and complete frog.

The hallmarks of an optimal frog:

1~ Healthy and not inclined to harbor thrush. Rubbery and firm when cut into.

2~ Straight sides.

3~Natural cleavage into two frog legs, each complete with its own very rubbery frog curtain. The frog curtain is an integral structure of a non compromised frog. It extends directly from the caudal end of each frog leg, over to the heel buttress on the same side. And it grows from the coronet, down to the ground surface. The frog curtain serves to occlude the caudal end of the collateral grove.

Yellow~Frog Curtain. Red~Central Sulcus/Frog Stay Aparatus. Green~Straight Legs

The frog curtain is a structure not often seen. It is the first thing to get compromised out of existence when the trim is off, and one of the last things to redevelop, along with a deeper frog stay, on a foot that is returning to balance and full size. Bracy Clark noted it’s existence on his hoof model circa 1820.

The frog curtain grows down from the periople across the back of the foot and has vertical striations, characteristic of curtains, hence the name. From a liquid dynamics pov, it can be postulated that the frog curtain serves to create a vortex of liquid/mud, when those things are walked or run through, and this resultant vortex flushes out the collateral grooves.

A deep and natural “V” shaped central sulcus is not so much a structure as a void left between fully developed frog legs. A true central sulcus does not need to be cut out , but serves as an indicator of a fully formed frog. The central sulcus opens out of the back of the foot in a ‘V’ when the foot is held in hand. The central sulcus is the underside and external extrapolation of the internal Frog Stay Aparatus, which extends up between the heel bulbs of the digital cushion.

If the frog is not optimal, the foot is not optimal. In an otherwise healthy foot, one not suffering something chronic, like founder or canker, if the frog is not optimal, the capsule is not yet where and how it needs to be. And the foot is most likely smaller than optimal. It is the capsule when trimmed incorrectly, that all to often causes severe compromise in the inner foot, and it’s the inner foot from which the frog and frog curtain grow. Most hooves I see do not have a fully functioning caudal hoof. Frogs are contracted, bars are curved or bent, heels are forward of where they should be, and the caudal foot is smaller than it should be. All of this can be corrected by maintaining proper break-over, and allowing the hind end of the foot to regrow.