Dissecting a Hoof – why would you benefit of it?

Written by Thomas Rast.

Last Saturday, 13th February 2016, we offered a course about the inside of the equine hoof – dissecting a foot. The first reaction of most people, especially horse owners is quite reserved. Some could never imagine to take apart the hoof of a horse, a once loved and respected animal. Some are afraid of eventual smell or the sight of dead meat/blood.

Let me share a different picture about it. I have done by now 6 dissections. I have been reserved in the beginning as well, afraid of the smell, of the sight, and of course it felt weird to take apart a hoof of a horse I once knew. But each single time I was fascinated, it was interesting and also beautiful. Each time I gained a deeper understanding of how the hoof functions. The Hoof is simply a stunning piece of nature’s engineering. Only by having a close look into the inside of it, I could truly understand it, get a clearer picture of how each single structure takes part in each step the horse takes.

Why should a farrier/trimmer/vet never cut into the live sole plane or carve out the sole to gain more concavity? During my first dissection I had a little shock on how thin even a healthy sole is – I knew that the horse was very sound when it was still alive. It is just about 10 mm thick! Imagining what would happen if it was thinned out, even just to remove the little layer of dead sole would cause the horse to be sore! Please don’t get me wrong, there are some rare cases where sole needs to be trimmed.

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Before going to the practical part of the day, I explained some basic anatomy and how the hoof functions.

Everybody is ready and curious.

The hoofwall is off. Here you can see the laminae. 

Everybody wanted to feel and take pictures.

Hoof capsule and and sole put together. Aren't the colors beautiful?

Here we peeled back the sole and frog. Each single time I am fascinated by these colors. 

Slicing off the lateral cartilages. The coffin bone is not extending all the way back in the hoof capsule. To illustrate better how much place the cartilages take within the hoof, I carfully slice of mm by mm until I hit solid bone.

Now we put the hoof back on the sole to show how much of the inside is made up of cartilage. This gives the hoof its flexibility and ability to adjust to uneven ground.

Here we cut off a slice of the frog in order to reveal the digital cushion above it.

Then I cut out the digital cushion itself. It is made up of fat and cartilage fibers.

Everybody wants to feel it again.

Here we cut the sole into stripes to evaluate sole thickness.

This was a healthy and sound horse. It was not in work though. Only 9 mm of sole! 

Now we take off the hide to reveal all the tendons and ligaments.

Fascinated faces. 

By pulling on the right tendons it is actually possible to make the foot move again. Like this the function of each tendon can be understood very easily.

Some people were not just fascinated but also a bit "shy"

Here you can see the back part of the foot, the frog and the digital cushion is missing.

We managed to seperate the hoof from the rest of the leg and put it back into the hoof capsule. You can see the joint surface of the coffin bone and the navicular bone.

Why is thrush painful to the horse? A horse with a sound foot will impact the ground with the heels and the frog first. Like this the weight, vibrations, impact energy are absorbed and cushioned by the frog, digital cushion and the lateral cartilages. These structures can be explored very nicely during a dissection. It is very interesting to see how the thickness of the digital cushion varies from horse to horse – congruent to the level of soundness. Thicker and denser on sound horses, thinner and softer on sensitive horses. During one dissection the frog had a deep sulcus thrush. We sliced the whole sole and frog in half – directly through the central sulcus. What this revealed was scary. There was literally just 1mm of tissue that separated the outside from the sensitive digital cushion. Hm…. When thinking deeply about this, what it might cause, I could easily come to this conclusion: If the frog has thrush and can’t protect the sensitive digital cushion anymore, the horse will be sore when landing heal first. So it will shorten its stride and land flat or even with the toe first. This can lead to a whole chain reaction in the horses’ foot and body. Tendons get over flexed, the digital cushion will degenerate because of lack of stimulation, shock is not absorbed as well and travels upwards through the horses’ leg and joints. The sole at the toe will get used too much; heels grow higher due to lack of use …. A bad cycle. My conclusion since this dissection: Always do my best to help my horse to have big healthy frogs – and also not cut them clean!

Even if it feels strange in the beginning – participating to a hoof dissection has always been a big learning experience for me.