What we do depends on how we each view the foot

[Phil Armitage]

When I very first started learning about the feet, I understood the hoof wall to be the primary weight bearing structure. I focused on that when I was trying to figure out how to prevent flares, dishes jamming the hairline, prevent qaurter cracks, toe cracks (butt cracks :) only kidding). Anyways as time went on I started to suspect that maybe the hoofwall is not the weight bearing structure but primarilay a protective structure. I would notice that any horn past the sole always wants to distort or break away. As I studied more and attended clinics and trimmed and shod more horses I began to realise that the sole, frog and bars and internal structures and tissue is the primary weight bearing structures not the hoofwall. This is the way I see it now and it impacts how I view products, trim and balance the feet. I believe one of the maine reasons for so many different views and debates on principles, methods and products is based on how one understands the form and function of the feet. Why do some believe the hoofwall is the primary weight bearing structure, if it is why does it stress, crack and flare as soon as it grows past the sole?

[calshoer]

I think folks believe that (as I used to or tried to despite the contradictions I would see) simply because the text books said it and we believed our teachers who believed the texts. And unfortunately the texts statements about the hoofwall were based on assumptions from just observing the sort of conical form of a hoof, (domestic hooves that had taken on man made parameters) , but not fully understanding how the insides worked. I never quite got over the fact that even though I was told the wall was primary weight bearing, how come all the barefoot domestic horses I was called to shoe in the spring were walking on the soles and frogs just fine? And how come the old texts, despite telling you the wal lwas supposed to bear weight also told you that the frog had top be on the ground.....I always saw that contradiction and never figured it out until I realized the wall was not really supposed to be the primary load bearer.
Just a load SHARER, and only the inner hoof wall, not the perimeter. A recent lecture on hoofwall cellular anatomy helps clear this up..the outer, pigmented layer (stratum externum) is more brittle than the inner unpigmented (stratum medium) and has a different cell shape and alignment pattern. So the two layers have different fracture patterns. This allows the outer layer to continualy break away while the inner layer redirects the fracture and stops it. Which is exactly how a bare foot wears. It rolls off the stratum externum and the horse is left walking on the outer edge of sole and stratum medium. Iam attaching ap ictur of a foto that the light happened tohit just right so you can see how sharp the demarcation is between the two layers of hoofwall. And in case anyone wonders, No it does not get darker more toward the inside just because it is thicker..if that was the case the darkening would not be such a sharpline. ..it would be gradual. That outer layer is SUPPOSED to wear or chip off.at the ground surface. Patty

[Gary_Miller]

When you pickup a hoof and see all the dirt packed in the sole it stands to reason that the whole hoof shares in the support of the weight of the horse.

So what is the purpose of sole relief and why is it so important when applying a shoe?


Gary
Still learning

[Phil Armitage]

Thanks Patty for that explanation. It really makes a lot of sense when you think about it. Funny you mentioned what you saw in the Spring, I noticed the same thing after horses were barefoot for the winter and wondered how they made it through the winter on hard frozen ground and outer wall was chipped and rolled past the sole without any problems. Gary, that is a good question I do not think sole reliefe is needed unless the sole that is contacting the ground or shoe is soft. This brings up another reason for the importance of shoes. That sole and inner hoof wall can become too thin if the foot is trimmed too short or wears off on abrasive footing or it could be weak geneticly, this can cause all kinds of problems. Shoes will protect this from excessive wear, however the shoeing method should be done in a manner that it does not place the sole and frog too far from the ground or frog support should be used. If you have a thin or sore sole situation sole reliefe is required, but provide it in the shoe not the foot. One of my favorite methods is to seat out the foot side of the shoe by hammering it out or grinding it, then use a leather rim pad on a wide web shoe. This works great for me and then after the sole regains thickness you can go back to a regular shoeing or barefoot. On a healthy foot and sole, I would think knifeing out the sole and invadeing something that is provideing structural support to provide sole reliefe is not a good thing. I recently attended a clinic and the Farrier doing the clinic is very experienced and stated that the hoof wall is the primary weight bearing structure, he gave no explanation and wasnt really open to discussing it. He also slammed Natural Balance and asked if anyone used Natural Balance I was the only one that raised my hand. A couple of people asked about the sole calouse and he replied he did not know of any sole calouse or what it was. He did balance the feet by useing the apex of the frog and said use common sense when removeing sole. He likes to start by trimming the toe, remove the flares and take a measurement from the apex of the frog to the toe and trim the heels so that they end at the same measurement. The problem I have with this is that it leaves a lot of unanswered questions about what is too much or not enough sole to remove. The sole thickness and hardness is probably the most important part of the whole job in my opinion.

[Dave Purves]

Good topic Phil. I believe that the hoofwall is the primary weight bearing surface. And the bars, frog and sole are secondary meaning they do not take the brunt of the stress of weight bearing. At home we all see the feet that are full of mud and dirt that does not come out until the foot is cleaned by human hands. However, I would bet that in the wild, horses travel so much, over such varied terrain that the mud and dirt would work it's way out on it's own. Like everytime the horse went to a stream or pond to drink, the mud and dirt would wash out. The domesticated horse doesn't have that option. Further more, if the sole was a primary weight bearing surface, then why seat out the shoe? Even the NB shoes our seated out. Why is that? If the sole is a primary weight bearing structure, then why do horses get rock sore? The reason that we trim horses is to keep the integrity of the hoofwall strong. Our domesticated horses don't get to wear down the hoofwall and that may cause distortions. But I've seen plenty of domestic horses that were two or three inches too long and still no distortion, and no chipping. The foot was perfectly healthy other than it was too long. I also believe that it depends greatly on where the horse lives. If you live in a really wet environment, that may change the way sole pressure acts on the hoof than if you live in a really dry environment. You do things alot different in Maine, than they do in Texas. I think it really depends on your style. I don't leave any sole pressure in any shoe that I nail on. I've done it in the past and the horse was sore. That is how I shoe a horse, you may never put your knife in the sole that is how you shoe a horse. I don't think it makes either one of us wrong, as long as the foot is healthy, the horse is happy, and the owner pays us. I also wonder why the sole is cupped. You would think, that if nature intended the sole to bear weight it would be flat and always at the level of the hoofwall.
Dave Purves CF

[calshoer]

As to the question of why sole relief..well, sole "loading"is quite different from sole "pressure". Loading is a give and take that allows blood flow. ....the sole is pressed as the horse places weight on it, then releases as it is lifted. It is a natual dynamic function. "Pressure" on the other hand is non-yeilding..it smashes the sole and keps it smnashed. Cuts off the blood flow. So when you are going t onail a meatal object to the foot it HAS to be so the sole is not pressed down by the shoe as it is nailed on.
I will address Dave's belief that the wall is indeed a primary weight bearing srtructure and that the dirt that packs in the sole is not really a support factor. He says that those feet wi self clean. Sory, but observations hve shown otherwise. In feral horse studies, by not only Gene but by other researchers, horses that live on the hardest driest ground have the hoofwall worn off all around the foot and literally walk on soles and frogs. And soundly. As well even those very short footed horses still have dirt packed hard into the commisures to fill the void. In the group of feral horses Gene studied that came from from hard rocky ground, the said the dirt in the commisures was hard to pick out. There was no place for dirt in the front half of the feet because there was NO hoofwall there to hold it in. Those horses who have no dirt available (living basically on rocks) have large spread out frogs that effectively fill the commisures. And in barefooted horses on softer ground, (including those in swampy areas like the east coast), the sole and frog are STILL supported because the longer unworn hoofwall either spreads /flares out of the way, or sinks into the ground until the SOLE takes up the support. In other words there is no way the hoofwall can be primarily bearing the weight unless a farrier shoes it and takes the frog and sole off the ground and somebody then regularly cleans the supportive dirt out of the feet.
Add Dr. Bowker's studies on the importance of coffin joint support upward through the frog and digital cushion ,and several other studies on sole callous structure and function and I find it hard to dispute that the frog and sole are not as (or more) important than the hoof wall.
And just to add a bit more fuel to the discussion, think about how foundered horses manage to survive and recover after the so called 'primary supportive' hoofwall completely fails. The horses utilize frog and sole support for ALL the weight bearing as the wall grows back in. Patty

[Phil Armitage]

This is a great discussion and it is a great topic. I believe it is a topic most Farriers don't want to go there. Dave I totaly agree with you on enviroment playing a huge role on feet. We have four different extreme changes when we go into our four seasons here in Maine and I can see how each change drasticly affects the feet. We can go from very dry hard ground to very wet and muddy very quickly, no way for the foot to adapt. Just to add to Patty's comment on foundered horses, what about the ones going through white line desease. I had one case last year where it started as Whitline in all four feet in a mare from down south that came up here. She then foundered rotated 14 deg. in the front feet. She is recovering and her right front was severly damaged. The whole time she went through this she was barefoot and all she would let me do is trim her. She would kill you if you tried nailing a shoe on, working with her was a challenge. I started with Foam blocks and all of the weight bearing has been on her frog and sole. The Vet insisted that I remove more sole in the toe, I never did and I explained to the owner that if I did, there would be a big problem. We soaked her feet in White lightning to kill the fungus and removed as much infected horn as I could, did nail on one shoe on her RF had to sedate her becuase there was a lot of hoof missing. I do think the feet weaken if the dorsal wall becomes too thin or is removed, it is definately a supportive and protective structure, but not like we think it is. There is definately more going on than meets the eye. This case and many others have taught me a lot and have raised many questions in my mind.

[Dave Purves]

Ok, I can see what you're saying Patty, however, how many times during any of those studies did the researcher pick up the same horses feet? Did they do it once a day, once a week or once a month? How about every couple of hours? Everytime I pick up a foot unless it's been cleaned before I get there it is packed with dirt and such. I also know that if that dirt and mud never comes out, I end up with thrush problems, and we all know how bad untreated thrush can be, so how do the wild horses deal with that? Some laminitic horses can go fine barefoot and bear weight on the sole, and frog and bars, however more often than not, they can't. We have to life the sole off the ground so the pressure on the sole at the apex of the frog doesn't hurt the coffin bone. Then we add support to the back of the foot to make up for the lack of support from the front. I worked on a pretty bad laminitis case a couple years ago, the mare is barefoot now, with alot and I mean alot of sole depth, but in the begining she was dead lame barefoot, with the sole bearing weight. I certainly think we can learn alot from wild horses, but I don't think that we can actually take enough data, often enough to be too reliable. The horses I work on, do just fine with primary weight bearing on the hoofwall, and secondary weight bearing on the sole, frog, and bars. It works for me. The other thing is, I understand about static and dynamic weight bearing, but when you seat out the shoe, do you know for sure, that the sole compresses enough to touch the shoe, and then bear weight? And If the entire sould should be bearing weight, than why are shoes open in the middle, I mean why don't we just nail on plates? And I still don't understand why the foot is cupped? I think we will all agree that a healthy foot is cupped, and most of the time a flat foot is not healthy, why is that if the sole should bear weight? I've seen the results of the sole calluse bearing weight dynamically, and it always ended in bruising. Maybe no lameness but definite have moon shaped coffin bone bruising in the sole. I know horse that if left with enough sole, would be fine with no hoofwall, I also no enough horses that are thin soled, and can barely walk barefooted with alot of hoofwall. I think that if the sole was designed to be a primary weight bearing structure then all horses could go barefoot, and we know that's not true.
jmo
Dave Purves CF
Don't mis-understand me, I do believe that the frog, bars, and sole are secondary weight bearing, with dirt packed absolutely. But the primary weight bearing surface of the foot is the hoofwall. If the good lord intended the sole to be the primary weight bearing surface He would've designed it so dirt did not have to be present in order for it to work.

[Bill Adams]

Hey Gary,
I wish I had been asking questions like you are when I started out. Keep it up.
Hey Dave,
I think the Lord may have forseen that horses would be walking on dirt, as He saw that beavers would need to bite trees or their insisors would grow too long and they would die.
Some horses are thick soled and some are thin, some are cuped some are flat, some have strong hoof wall and some weak some live to twenty five in the wild but the advarage age is seven (BLM census). Some get tursh real bad and some don't and they live in the same pen.
I think that (here it comes) the whole foot is the primary weight berring part of the leg. Different parts of the hoof handle more load than others as we see the quarters flair and break first. the sole is thicker in the calous and is much weaker just in front of the apex of the frog. We have to treat it like it all works together. Just recently I quit triming off the burnt sole around the wall before I nail the shoe, no problems. Good suport not pressure. Pressure would be when the sole is too thin. Then I seat out the shoe, but by the next day that space is filled with stuff or the sole has droped to the shoe. For years now Ive only taken the dirt off the sole unless it has a couple of layers from neglect.
On friday I shod three horses on a large cattle ranch that had been turned out on several thousand acers since last fall. Mostly their hoofs were below the sole (or above I should say) anyway the shoe only touched hoof about half the time.
The problem was they were sound as sound could be. We shod them because they had to go to work packing the cowboys over the hills chasing persective BBQ victims.

My $0.02,
Bill

[Dave Purves]

Hey, thanks for your input Bill, I understand where you're coming from. And yes, the whole hoof compliments itself during weight bearing. My only problem with this is stating that the "sole of the foot, is the primary weight bearing surface." I beleive that it is meant to bear some weight, but that it plays more of a secondary role, more passive weight bearing. Just like the ranch horses that you shod, I've done the same thing, and they are perfectly sound. However, I've also tried to do it to other horses that were lame from the sole pressure. Just because a few horses can do it doesn't mean that the sole is primary weight bearing. Like I said before, I think the hoofwall is the primary weight bearing surface, and the frog, bars and sole are secondary. In fact, I beleive that the frog, and bars are more primary in weight bearing than the sole.
jmo
Dave Purves CF

[Gary_Miller]

I beleive the sole is concave so dirt can be packed in to provide traction. Dirt against dirt provides a whole lot more traction than a slick hoof wall would. Is that not the sameway horseshoes work dirt packs around the groove where the nail holes are.

Also I beleive the reason wild horses would not have a problem with thrush because the environment is much cleaner than where demesticated horses are stored (stabed). Good dry dirt is cleaner than wet horse manuer.

Gary

[coreen harris]

Hey all, I've missed a lot! This is an interesting thread. Just today I brought in my nav mare - I had forgone trimming her over hte hard part of winter as we had mushy mud that froze into a terrain harder on their hooves than any rocks. I could now see removing any hoof at all from anyone with the ground like that. Today was trim day for her, finally. What really surprised me was the hardpack in her hooves. It was a dirt version of ice***** that they get in the snow. Man she was comfortable like that too. She was walking literally on the middle of that hard pack with an ideal rocker. I kind of felt bad robbing her of that, but she had started to show vague soreness in her "bad" hoof... well there is a good old fashioned bruise there. dang. (BTW, this mare is navicular disease on rads, plus syndrome due to contraction) No wonder she looked better this morning than she did yesterday, she had that nice pack there.
As to concavity, I can't even remember where I got this, its been eons, but someone out there thinks it has something to do with how a horse knows where it is and when other horses (or other types of critters) are there by acting as a sort of tympanic structure.

I think the weight bearing activity of the sole varies horse to horse. I do only trimming at this point (hoping to be in farrier school this summer) so that's what I get to observe. Some horses seem to like to have active weight bearing on the very outer edge of the sole, some like to involve the toe callous or whole sole callous, and some are no-sole hooves. I have not seen any correlation yet between this and frog size/texture - that seems to be more dictated by overall hoof health and terrain.

Coreen

[Bill Adams]

Coreen,
Are you saying that someone said that the hoof is cuped so that the horse can "hear" something comming?
No wonder this horse wispering thing never worked out for me, I was using the ear, of all things, what a dope I am.
I hope you didn't spend a lot of money to hear that. (grin)
It would probably work well with a T-Rex on your trail but I don't know about a mountion lion.
Bill

[cowboy_bc]

Hi all,

"Are you saying that someone said that the hoof is cuped so that the horse can "hear" something comming?"

Bill

Lets just keep that quiet next thing you know they will be saying that horses with shoes can't hear with their feet and we don't want those barefooters useing that as another reason against shoeing, hee hee.

Kevin