Cracks Part 1: The Real Cause of Hoof Cracks

Hoof CrackHoof cracks seem to cause a lot of worry and stress for horse owners. Even tiny little ones. I think there’s a number of reasons for this:

1. You can easily see them as they’re visible without having to pick the foot up
2. They look bad, particularly on a white hoof
3. No matter how little you know about a hoof, you know a crack looks wrong
4. Many people seem to like something to worry about
5. As a hoof gets longer, so does the crack
6. If you don’t know why it’s happening, it seems out of your control and potentially dangerous.

So why do cracks happen?

The short answer is IMBALANCE.

The longer answer is also imbalance, but I’m going to explain what I mean by that…

Any imbalance can cause a crack. An imbalanced diet, an imbalanced hoof capsule, an imbalanced hoof landing, imbalanced posture, imbalanced internal systems – like digestive, circulatory, lymphatic, endocrine or urinary system problems.

So yes, it’s imbalance – but that doesn’t necessarily mean it’s caused by an unbalanced hoof capsule, nor does an unbalanced hoof capsule necessarily mean that there’s been an poor trim (and I’m referring to barefoot trims as well as trims followed by the application of a shoe).

Lets look at possible causes of an imbalanced hoof first, then we can talk about why cracks develop and what we can do about them.

We all aim to achieve the best balance we can with a hoof, but sometimes it’s just not possible. Say you have a hoof where one side is short, and the other side is even shorter. Yes you can achieve medio-lateral balance by trimming the short side to match the even shorter side. But that’s balance in only one dimension in only one position.

What will happen as a result of that, is you’ll unbalance the hoof capsule by making it too short. Yes I consider a hoof that is too short to be unbalanced. You will have unbalanced the nervous system – by causing pain or discomfort due to lack of structure, and interfered with the proprioception .

This in turn is going to cause a change in the gait as the horse tries to adjust, which will not only cause an imbalance in the way the hoof lands, causing the concussion and stress the hoof receives when moving to be unbalanced, but it will also unbalance the muscular system.

It may also affect posture, meaning that the pressure the hoof capsule receives while the horse is standing is unbalanced – remember pressure stimulates growth, so then your hoof capsule will be growing in an unbalanced way.

The bodies first response to a problem is to send more blood to the area to assist in healing and protection. Sounds like a good plan, but this is the hoof capusle and the sending of more blood is also known as inflammation.

Inflammation in the hoof is going to cause a circulatory problem, though in all honesty, it also creates pressure, so the hoof capsule growth rate will speed up, which is a good thing in this particular case where the problem is caused by the hoof being too short. The down side is (see above) it’s going to increase the speed of unbalanced growth.

(Not to mention, laminitis as a method of increasing hoof growth rate while effective, is fairly undesirable. I believe it could be considered a ‘shoot the dog’ method!)

That’s a brief rundown of why trimming a hoof with that problem into medio-lateral balance might not get you the result you wanted, and there’s a lot of information there so you may or may not have noticed the really important bit that’s missing. Wood – trees anyone?

There’s a question that should have been asked way before any (hypothetical) trimming (of our hypothetical horse) happened…

Why is the hoof unbalanced? ie Why is one side short? Why is the other side shorter?

Answers will fit into 3 categories:

1. It grew that way
2. It wore that way
3. It was trimmed that way
(4. a combination of the above)

Number 3 is the easiest to fix – give it time to grow and don’t trim it that way again – problem solved. Easy peasy.

Number 1, it’s not possible for a foot to grow too short, but it is possible for it to be growing too slowly, and even more slowly on one side. In which case it’s a growth rate problem primarily with a secondary imbalance in the gait and posture. For growth rate problems see the series of articles on conditioning. For imbalance in gait and posture see a good bodyworker.

Fix the growth rate problem first. You’ll find the imbalance in the hooves is contributing to the gait and posture imbalance. Once you’ve fixed the growth rate problem, you can minimise the hoof imbalance problem with regular trimming, while you address the neuromusculoskeletal problem (gait and posture) that’s causing the hoof growth imbalance.

If you don’t fix the growth rate problem first you’ll be setting yourself up for a long, frustrating (and possibly expensive) journey that never quite gets you to your goal.

Number 2 is almost certain to be a factor. It’s likely to go hand in hand with number 1 but in rare cases it can be the sole cause. (I’m vaguely wishing I’d used A’s and B’s instead of all this talk of number 1’s and number 2’s but we’re here now so lets work with what we’ve got!)

The rare cases where it’s the sole cause of the issue is when a horse has received an unusually high amount of wear, with an unusually imbalanced gait. ie something happened to cause your horse to get out of the field and go galloping down the roads.

Like I said – rare but possible. I’ve seen it once in the last 7 years. The solution is much the same as if the hoof have been trimmed too short. It has been trimmed too short. I believe in some circles it’s known as Asphalt Trimming. I suppose it would be a Tarmac Trim in the UK which has a much better ring to it now that I think about it!

Almost solely in this category would be an injury that’s causing an unusual wear pattern, but in this case you should be able to notice the problem and provide some sort of wear protection for the hoof before it gets too short.

Also the injury would reduce the amount of work the horse receives making it more manageable, so hopefully you have one side ok and one side longer – which is much more easily corrected than short and even shorter. You’re probably already treating the injury – so once that’s healed things should go back to normal, whatever normal was.

If you have imbalanced wear, the the way the hoof capsule is interacting with the ground is imbalanced. This means you have an abnormality in the gait. It may be conformational, in which case, get used to it – conformation can’t be changed.

I mean – by definition, conformation can’t be changed. It could be worth speaking to a good bodyworker though as many things that are thought of as conformation issues are in fact muscle imbalance, which can be improved and treated. While I say ‘get used to it’ do confirm it’s not correctable first 🙂

Conditions such as arthritis and old injuries that have caused restriction in movement could also fit into this category where there is a gait abnormality causing unbalanced wear.

In all these gait abnormality cases as long as the growth rate isn’t too slow, and you have regular trimming the hoof capsule imbalance shouldn’t cause too much of an issue, but may cause a crack.

There’s a bit of a kicker to hoof wear/growth patterns related to gait abnormalities, regardless of how long or short the hoof is. It’s in the physics of it. Dredging up my A-level knowledge, which was a very long time ago now, there’s this formula which for some reason I remember…

I = Ft

Granted not the most complicated formula to memorise 🙂 Impact = Force x time.

This means that the longer it takes a moving object to slow down, the less force is placed on that object. Think of a car slowing down. If you break sedately it’s comfortable. Drive into a brick wall and you stop really rather fast, receiving enough force to wreck your car and cause injury to yourself. Also it’s why drivers can often survive the most dramatic looking crashes in car racing, the longer the crash takes the less force their body is under (assuming it’s not spinning etc)..

What has this got to do with hoof landing? Stick with me here and I’ll tell you…

When a hoof lands correctly, it should land (subtly) heel first. The 2 heels won’t be exactly together, but it’ll be close. The heels slide along the ground just a little bit as the rest of the hoof makes contact with the ground during the stance phase of the stride.

The slide is important, it reduces the stress on the body, it’s why studs cause so many issues for both horses and humans, the foot stops too fast putting too much force on the body.

This means the heels slide along the ground the most, thus receive the most wear during landing. (the toe receives more wear than the heels during breakover, so it evens out as long as the stride is balanced)

Lets use an example of a horse who lands to the outside quarter of the hoof capsule, which is a common gait abnormality that often goes unnoticed. When it’s mild, it barely affects your life, if it’s severe then you’re probably aware your horse’s hoof grows wonky.

I’ve seen this cause a hoof an inch imbalance over a 6 week period, so decide for yourself what’s severe. (the horse was still in work and perfectly happy – he had the growth rate to deal with it and trimming every 3 weeks – for obvious reasons)

So we have a hoof landing on the middle of the outside wall. The part of the hoof capsule that lands first slows down more gently, and receives more wear. The part of the hoof that lands last slows down more abruptly, and receives very little wear.

This means the inside (medial) wall of the hoof capsule is receiving more force than the outside (lateral) wall. Force is proportional to Pressure, and Pressure stimulates growth.

The kicker = the outside gets more wear, the inside gets more growth

Awesome!

Poor posture can also cause imbalanced hoof growth. When a horse is standing perfectly square, then the hooves are receiving relatively even pressure. Standing base narrow, or pigeon toed however, tends to cause more weight to be placed on one side of the hoof than the other. As does favouring one foot over another.

Pressure stimulates growth, so the side of the foot that is receiving more pressure, is going to grow faster.

In the next post, we’ll talk more about different types of cracks.

What do you think?
Put your 2 cents in and tell me in the comments below or on the Facebook or Twitter page.
Debs

Want to read the rest of this series?
Part 2 http://hoofgeek.com/cracks-part-2-the-shock-of-it
Part 3 http://hoofgeek.com/cracks-part-3-are-you-cracking-up

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