Tuesday, September 6, 2011

The hoof mechanism

Now that you know what the back of the hoof is made of you can understand how the hoof mechanism works. In a nutshell: When the horse weights a foot, that weight pushes down and expands the digital cushion which flattens out the live frog and pushes the lateral cartilages outwards. When the weight is taken off the hoof the live frog springs back to its original shape and the lateral cartilages move back in.

Makes sense, right? Check out Cheryl's collage below for a visual aid.

The hoof mechanism needs certain conditions to work correctly, for instance the foot must be disease free and the shape of the capsule (hoof wall) must allow the hoof to expand and contract. That means no thrush, no imbalance, and no contractions of the hoof wall- any of those will impair the hoof mechanism and will result in negative impacts on the joints.
  • If the digital cushion is too thin then too much pressure is placed on the live frog, it can't absorb all of it and transfers it to the heels, they can't absorb it either so they get crushed. At the same time, the shock that should have been absorbed by the digital cushion gets sent up the leg, creating joint pain all the way up to the back.
  •  If the live frog is weakened by disease it can't flatten and spring back into shape, this causes pain and doesn't adequately push apart the lateral cartilages, this will also put too much pressure on the heels. Again, this will increase the shock sent up the leg. 
 See how this all works together?

You know how they say that each hoof acts as an ancillary heart for the horse? I estimate that it is the hoof mechanism that serves that function. Remember how I said the lateral cartilages are full of blood vessels? The hoof mechanism essentially "pumps" those lateral cartilages, moving the blood up and down the legs.

"But but but," you say, "I thought that was the frog."

Not a chance, the frog doesn't have any blood in it so how could it pump any? Speaking of frogs, here's another bit of info that might blow your mind, it certainly almost caused a mutiny in Oregon: The callused frog, the bit that touches the ground, is not essential to the hoof mechanism. Chew on that for a minute.

Are you leaping around and shouting now? So were we. Cheryl's theory is that the callused frog, the bit that touches the ground, is only there for comfort and protection- it's the live frog that acts as a trampoline supporting the hoof mechanism.

This theory actually gave me quite a bit of relief. You may recall that I had to cut Coriander's frogs off after his awful thrush infection last fall. I was sweating bullets that I was causing him harm by doing so, except that after I did it he was instantly more comfortable. It makes sense now, I treated his live frog and healed it from the thrush and then I took off the uneven pressure created by the nasty remains of the callused frog. Voila! Sound horse, without any frog touching the ground.

Here's another thing that might shock you to read me saying: Shoes don't shut down the hoof mechanism, they only hinder it. There's a good reason why farriers don't put nails close to the heels, they know that they move outward and won't hold the nails. If you have your horses shod ask your farrier to show you the heel wear the next time your shoes are set, you'll probably see marks in the metal from the heels moving in and out.

Does that mean I'm rethinking keeping my horses barefoot? Nope. I still don't like shoes because of the added concussion landing on metal adds to the joints, that they take away the heels natural independent suspension, that they open up the hoof wall to fungus and bacteria via the nail holes, and mostly because they force the horse to stand on their laminae (via the hoof wall). Again, I believe horses should stand on their soles, not the hoof wall.

If this has piqued your interest, Dr. Bowker has an article you might want to read here.


  1. Very interesting about the frog. Well, really the whole post was interesting. Thanks for the information.

    I'd prefer my horses to be barefoot but right now Dusty does need the support of her shoes for her founder. She always went barefoot before and if her foot continues to do well once it is all grown out, she will probably be barefoot again.

  2. Super interesting! Dee is getting her sliders pulled for the season next time the farrier is out. I'll have to make sure I get to have a look at them.

    I admit part of me was wishing Dee had shoes up front this past weekend. The area between the barns and the show ring was so hard and rocky...I could tell it was uncomfortable for her. But maybe by next year her feet will be a bit tougher if we keep going the way we're going.

  3. GHM- if it ain't broke- don't fix it. It sounds like she's improving and that's all that matters :)

    Story, remember that hooves will adapt to the footing they live on. If she's living on soft, grass pasture then she won't be equipped to handle hard, rocky ground. I doubt that one or two days of it did her much harm though. Can't wait to read how you two made out!

  4. Yes, I was *internally* leaping and shouting!

    God, how did I go so long without learning about hooves? They are fascinating!! For most of my equine life, all I knew about hooves was, "That's the frog." Lol.

    I remember reading somewhere that they found shoes (and, in fact, all peripheral loading) causes the hoof to lose blood flow. For stalled horses with peripherally loaded hooves, there was a split second during every heartbeat where there was no blood supply from something like the fetlock down. Scary! SO glad my boy is barefoot!!

    Thanks for sharing all of this OSNHC stuff!

    Oh, and I thought you would like this -- I was on COTH and responded to a thread about farriers vs. barefoot trimmers. I said that I recommended OSNHC trimmers because I've had such great results with mine. The farriers were scoffing and saying that nobody could learn to trim from a 5 day clinic, etc. I said, "The proof is in the trim." I posted pics of Salem's hooves after my farrier had trimmed them, and then after Candy had trimmed them. Guess what? Not a PEEP from any of the farriers (and they are quite a vocal group!). HA!

  5. Well they do have a point, I now know what the hoof should look like when I'm done but it will take me lots and lots of hooves before I can do it reliably every time in a timely fashion.

    Those farriers, gotta love messing with their paradigm ;)

  6. "At the same time, the shock that should have been absorbed by the digital cushion gets sent up the leg, creating joint pain all the way up to the back." I'm afraid that's what has happened with Lilly... and it's just getting to the point where she can't tolerate the pain any longer which is why all these issues are showing up. :(

    Another good post I'm adding to my pile!

  7. Really interesting. Thanks for sharing.

    I am a science teacher and have completed more dissections than I can count, but I still get grossed out by cadaver hooves. How do you deal? ;)

  8. One of the things I always hear people complain about (and it's a common complaint from me as well) is that if you have horses, you likely live in a rural area. Which means it's hard for people to travel TO you to do things like fix a washing machine or trim a horse. Horse owners should all know a little something about hoof mechanics--we have to learn about feed and vaccinations and swap stories about what to do when the gnats are bad, etc. Why not learn some cool stuff about hooves, too?

  9. in2paints- you're welcome, I know that every bit of knowledge helps.

    Val- I've only handled two cadaver hooves so far so I'm not like an expert with them or anything- but it helps me to not think of them as coming from a specific horse that I would be sad about, I think of them as learning opportunities.

    Fetlock- exactly, I think that's why most people start trimming themselves. They are the ones who really need this knowledge. Hopefully some of them find this info and it helps them out :)

  10. Interesting hoofmechanism videos with cadaver feet under pressure from the swedish hoofschool: http://www.youtube.com/watch?v=fd77zwRRYLM