Underrun Heels Explained
Part 1

027 Underrun heels explained
Underrun heels are a very common problem (or pathology) with hooves. It’s so common to see underrun heels that many people don’t even realise that it’s not ‘normal’ for a hoof to be that shape.

You’ll often hear them called low heels, though I’d argue that you can have low heels without them being underrun, it looks pretty similar. You’ll also hear the terms, underslung heels, collapsed heels or, if people are getting really technical ‘splaty foot’ (used a lot with TB’s – they have an upright foot and a splaty foot; right?)


Lets define our terms. What are underrun heels?

Sometimes they are defined as when the tubules of the heels are at a more shallow angle than at the toe. But I don’t like that… I’ll show you why…

Here’s a diagram of underrun heels using the above definition

Underrun heels 01

Yep, that works fine. Only… here’s a diagram of the exact same heel angle but they wouldn’t be defined as underrun by the above definition.

Underrun heels 02

Why? Because the toe has ‘run forward’ too, as it very frequently does when you have underrun heels. I would love love LOVE it if the toe running forward cancelled out the heels being underrun. But alas it doesn’t, it just means you’ve got underrun heels AND a toe too far out the front.

I prefer to use the definition of the heels are further forward than the widest part of the frog.

Underrun heels 03

Widest part of the frog is the green line. Back of the heels is the orange line.

With the heels running forwards like this, the quarters can get pushed out to the side. This can be mistaken for flare, particularly if someone is using a photo to assess the hoof.

Underrun heels 04

I have no explanation for the pink tint on this photo, so please don’t let it distract you from seeing that flare! Granted, there’s not a huge amount of flare on this foot, it can get a lot worse where underrun heels are involved. This is how flare is commonly assessed, particularly if giving an opinion from a photo. But is it flare…

Underrun heels 05

This is a side shot from where I was holding the rasp to show the flare. The rasp is being held in the direction the tubules should be going if the heels weren’t underrun. You often don’t get to see it from this side and compare when you’re looking a photo.

Here’s how it looks when I’m holding the rasp in the direction of the tubules, which is how you should be assessing the flare

Underrun heels 06

You can see how the rasp is at the same angle as the tubules of the hoof wall.

Underrun heels 07

TA DA! Flare be gone! No trimming needed!

It really does depend how you look at things!
In the next part, I’m going to show you what’s going on inside the hoof with underrun heels.

How does it affect the laminae?
What happens to the pedal bone.
What’s going on with the lateral cartilage.
All the stuff you don’t see when the hoof capsule is in the way.

Underrun Heels Explained Part 2 is here

NB. Not for the squemish!

Underrun Heels Explained Part 3 is here

Does your horse have underrun heels? Are you not so sure now you’ve read this post?
Got any questions, comments or concerns…

Let me know in the comments box below, or over on the facebook page.


  • ouida says:

    That is a very interesting post! and just shows how different things can look by tweaking the equipment. I believe my boy has underrun heels and also flare which I have worried endlessly about and bought a rasp to tackle it but my trimmer says its really not that bad so the rasp was a bit of a waste of money as she sees no reason to do anything between trims.

    • Hoof Geek says:

      well as you can see here he might not have as much flare as you think.

      Trust your trimmer. It’s what’s going on on the inside that counts…

      Besides – trimming flare is really hard work, Use the time and energy to have fun with the fella 🙂

  • Sarah Jane Saull says:

    Great info thanks Debs 🙂

  • […] 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… […]

  • Glory Douglas says:

    My older barrel horse seems to have those kind of heels..What can i suggest to my horse shoer to get them started on a better direction
    he sometimes is lame when barefoot.

  • Rebecca says:

    I have a horse with under run heels, my main concern is the fact that I haven’t found a competent trimmer with experience, at at this point I asked myself why would it be better to shoe him, is there a shoe in the process that could help ? thanks for now !

  • Deborah says:

    Amen and amen. My farrier in America was very adept at keeping my horse, who has a very strong tendency to get under-run heels, balanced sound and happy for over a decade. I moved him to France permanently and have been going crazy trying to find someone who actually understands horses hooves and underpin heels – they just chop the toe off and call it a day….sigh…

  • Paige says:

    OMG! Best article I have ever seen in this! Thank you so much. A lightbulb just went off for me. My mare has bad underrun heels due to always keeping the heels a little long due to the central sulcus thrush that I am always fighting. I was told that if I take off too much heel, she will be lame and not move enough to stimulate her frog! I believe this to be somewhat true but now I think we are in a vicious cycle. Not sure which one takes priority.

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