What’s happening to the internal structures in a horse with underrun heels and how do the forces on the hoof capsule help or hinder the recovery?
In part 1 we looked at the hoof capsule,
In part 2 we looked at the position of the internal structures,
Now let’s look at how they go together…
When the heels have underrun the laminar that grow the hoof wall are pointing forwards more than they should be. This causes the heel purchase (bit the horse should be landing on) to be further forwards. In part 2 I showed how this has a negative effect on the pedal bone, but what does it do to the other internal structures?
I’ve rotated and marked up the photo of the foot with the horn at the heels missing to show what affect ground forces may have. The yellow line shows where the ground level usually is for a horse with underrun heels. Obviously it’s not exact, it will depend how long the heels get.
The blue arrow is showing where the direction of pressure is going for the horse who is landing correctly and while standing. You can see how the pressure will actually be pushing the heels further underrun (but just a little bit more).
While this looks bad, if you can get a correct landing, and provide enough healthy stimulation to the frog, and thus the digital cushion and lateral cartilage, then you’ll find the heels will recover in spite of the slightly less than ideal direction of pressure.
The important part is getting the healthy stimulation on the soft structures. While they are soft – they’re also remarkably strong and hold the shape of the hoof together far more than we give them credit for!
If a horse is landing more heavily on the heel, and it’s highly likely they are, then there’s going to be a problem. Often the easiest way to spot an excessive heel first landing is when a horse is walking towards you. They’re flicking their toes in the air just before they land. (sometimes this is mistaken for good extension or ‘floaty paces’)
Look at the hooves, if you can see any sole or a dark shadow under the foot as they land, then they could well be landing excessively on the heel.
The orange arrow shows the direction of force on the hoof when there is an excessive heel first landing. It’s easy to see how this will crush the heels underneath themselves, thus causing and increasing underrun heels.
You can feel this for yourself, if you like. Right now! Stand up. Yep, I mean it! Up on your feet give this a go – I promise it’s not going to be like an exercise video, or anything 🙂 (though now I think about it, the idea of a bunch of people all over the world standing up and jumping about while reading this post makes me smile!!)
You need to be wearing shoes for this. Walk a few steps normally with a slight heel first landing. You’ll feel your foot slipping forwards very slightly in your shoe, or your shoe is being pushed backwards. That’s normal heel first landing and stimulates the heel structure just how we want it.
Now walk a few steps, but just before your foot reaches the ground, flex you ankle as much as possible so you land more to the back of your heel. You’ll feel your shoe pressing up against your heel and your shoe is being pushed forwards.
If your shoe were a hoof capsule, it would be underrunning.
There’s a number of ways of trimming underrun heels to correct them (allegedly), most of which involve taking the heels lower than they should be. For me, this raises a number of questions…
1. If the problem is caused by how the horse is walking, how can it be fixed with trimming?
2. The lower you take the heels, the further back the heel purchase is, so you’re putting the pressure on the back of the laminar, increasing the crushing effect, so how are you helping?
3. What caused the problem in the first place? What have you done to address it?
4. Your solution should address the cause of your problem… If your solution is to trim the heels lower than normal, then the problem you’re addressing is that the heels weren’t trimmed lower than normal… Does ‘lack of the heels being too low’ cause underrun heels?
So some of those questions sound fairly ridiculous, I know that… But they’re kinda valid… Just because something is being done all the time, doesn’t mean it’s well thought through!
I completely believe underrun heels can be fixed, I just don’t think it’s achieved by trimming tricks. A good trim is essential, of course, but that doesn’t mean the trim is the driving force behind the hoof recovering. Similarly I don’t think shoes improve things all that much.
Stimulating the frog, digital cushion and lateral cartilages in the right way, by using a balanced trim, exercise, nutrition, and correct movement is what I think is going to get you the results you’re after. The really good news, is 3 of those 4 things are completely in your control…
Let me know in the comments below Debs
Do you know a horse with this problem?
Has this post helped you understand why it’s happening?
Let me know in the comments below
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