Frog -

Time Walker

This horse came to me with flat frogs that had only a hint central sulcus. As his feet have restored his frogs have gone through cyclic changes with the central sulcus going back and forth between somewhat open to pinched. In April of 2021 I saw indication on this frog that this cycle was coming to an end* on this foot, with the hope of his feet being restored to full size and balance a real possibility. They’re not there yet. But stay tuned.

*May 2025 edit: The cycle was, as it turns out, just ramping up. They’re still not fully restored, but they’re so very much better. Better looking to me, and better feeling, as per the gentleman himself.

This is where this foot started, or at least…where it was when he came to me just coming six.

His soles were hard and dark grey, and very thin. His frogs were hard and dark grey as well. He was walking on his perioples and hairlines at the caudal ends of his feet were all on the ground. He was uncomfortable on all but soft pasture. His hamstrings were rock hard, and his stance was camped under. I’d noticed too that when he walked, he would not extend his hind legs past vertical, always walking under himself in back.

I’d been taking pics on and off for a few years, but these snow scrubbed feet re-piqued my interest and hope. And holy skew, Batman.

That spot in the crack at the back of his ‘heel bulbs’ was so odd. It looked very much like what is sometimes found being held onto by oysters.

The periople turns white when waterlogged. The dots follow the growth lines of the periople and highlight how the back of the foot had been pulled down and under from where it should be. The skew in the foot is almost all worked out.

More waterlogged periople. And awkward growth at the fissure between the ‘heel bulbs’.

The fact that periople turns white when waterlogged is very helpful in seeing better what is going on with these feet. You can see how it is unfolding out of the back of this foot.

When I uploaded and edited this pic, and saw the ‘marker’ that is traced in yellow dots I got SO. very. excited. At this point I’d been training my eye to see the movement in the structures of the foot as regrowth occurs and this contiguous line told me that we were finally, maybe, in the home stretch of waiting for the soft structures of the caudal foot to grow back out from where they’d been pulled under.

This central sulcus was deeper than it looked. I could get my thumb in there half way up my nail when treating for thrush.

A bulge? You do you, boo.
You can trace the growth lines in the periople around the back of the foot up around the front of that false central sulcus. It’s not totally unlike watching a hot air balloon unfurl.

Another thing that changes is the amount of ‘flesh’ within the periople. Eight months earlier that area was much thinner, less ‘full’ looking. The skew is back a bit on the lateral (right) side again.

All the while his frogs have been sub par, to say the least. When I first got him they were hard grey/black, unforgiving, unfriendly wedges of nothing-that-seemed-alive or vital.

Every time I look at this pic that pattern of grow out there in the central sulcus reminds me of crab mandibles. And look at the space building along that center line between the bulbs. Also, that bit between the periople and the ground surface, that’s frog curtain. It’s not all it is meant to be, but another unexpected, delight-inducing realization.

See those two flaps there in the crevasse of the central sulcus? I’ve seen those on so many feet. I’d opened up the central sulcus to more easily be able to treat for thrush. And because I was curious what was going on under there.
This was the last time I trimmed anything away from the central sulcus. I wanted to watch to see how it would change without intervention.

It boggles my mind just how much movement, growth and change can happen in a foot in just a few weeks. Look how deep in that CS is. And how much more plump the bulbs are than in the previous pic.

Look at that central sulcus opening up. And at that frog stay growing in, back, and up.

I put this in as the shadow fleshes out a bit more the depth of the thing. That there is the frog stay. It will continue to grow in and move up to it’s rightful place between the heel bulbs at/in the hairline. There’s so much here that still has yet to unfurl.

I heard once that pigs grow bone then flesh then bone then flesh. I’ve since seen similar patterns in other things. In the past week, it looks as if these heel bulbs there at the periople have plumped out. And just look at how wide the area proximal to the frog stay is. And much thanks to a rainy day for highlighting exactly where the periople is. Notice how it is no longer shooting up between the buttresses.

The heel bulb/periople area is nowhere as thick as a few months ago. We’re coming into new coat season, and I’m thinking that between the minerals that demands from the body, combined with the growth that’s going on in all four of his feet (his hinds hoof walls have lost quite a bit of color over the past few months) I’ve decided to go get a bucket of Frank Lampley’s minerals, as it’s a stellar product and he’ll eat it straight if he needs it.

At this point he’s had three days of the Frank Lampley’s. I write that as a ‘let the record show’ as I’m not keeping track anywhere else. I’m always a bit bummed when my pics are not clear, but it’s still clear that there is some plumping going on in his caudal hoof there under the stretch of periople. The clefts around that protrusion don’t seem as deep and there’s more room between it and the hairline.
He’s got these back-of-central-sulcus-clefts going on on all his feet at this point. His hinds are bringing up the rear, with his off hind furthest from good, but it’s both interesting and heartening progress.
It’s alarming to think just how small some horses are having their feet trimmed.

Periople has thinned out considerably since this past September. Central sulcus has deepend and thinned, both from the caudal foot at the hairline growing out.

The staining and frog changes here are due to it being “stand around the hay manger in urine soaked hay and poo” season. I’m glad it’s coming to an end. There seems to be chuncks of heel and bar growing in there on his lateral (left of pic). Tubules newly uncovered often first regrow with less pigment at first, and darken up later.

Heels look long, maybe true, but given how drawn forward the caudal
hoof is, as indicated by the shape of the frog, heels are growing down
from where the heel quarter would be in a fully expanded foot. Dropping
these heels would strain the bony column and the system of softer fascia
supporting it.

Quite a crack there on the lateral heel/heel quarter…

Of interest to see how much has fleshed out there were the central sulcus/frog spine is regenerating. Interesting too how the periople gives way when grown out of (at the lateral heel).

Not sure what insult took that medial heel out. Pics like these that make my eye twitch, and have me out addressing balance the next day.

More growth at center caudal… Still has that crumbling medial heel buttress. Check out the fold in the periople where the heel buttress comes through.

And now…expansion there at the back. And if you zoom in on that white bit of buttress growing down from the lateral periople, you’ll see that it’s new growth.
New growth wall often first comes in with little to no pigment. See too how when the periople (on the lateral) thins out during this phase of regrowth that it leaves the heels looking even more high. Granted, this is pre trim, so they are a bit high…on the lateral, anyway.

Poochin out at the central sulcus again. And low the bit of new (unpigmented) buttress continuing to grow down on the lateral.

So clean…

It’s fun too, to watch the hairline change…

Still with the lateral heel buttress growing in un-pigmented.

I feel like that there is a whisper of a naturally open central sulcus…

Still more unpigmented sole there on the lateral. And check out the change in trajectory mid way down the buttress.

There’s a lot more creamy sole coming in…

Wondering here if we’re not about at the end of what has yet to grow out at the central sulcus…

Well, I guess the answer to my wondering is “Not quite yet.” But again, check out the flap there along the inside of the central sulcus. That’s looking like a natural terminus to me. Again, love the water soaked periople shots for added clarity. And appreciate again, in water logged clarity, how much more creamy sole is growing back in.

Bonus sole shot. Again, look at those triangular flaps at the central sulcus. Those aren’t cut out. Those grew that way. I’m pleased as punch with the improvements in these feet. Everything’s improved. Not 100%. I’m not sure if 100% is achievable given how early he was shod and how bad his feet were. Time will tell…

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.

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.