Here’s a question from Jess, multi-part questions in fact.  I like multi-part questions 🙂

If you consistently trim away flare does it cease to grow back? Or does the mechanical stimulation from the rasp trick the hoof into thinking that it is wearing away fast and therefore the hoof grows faster resulting in more flare?

Is there any evidence to suggest that the mechanical separation at the white line caused by not trimming is painful for horses?

Firstly, let’s define flare.  For me, flare is simply where the wall has got thicker.  I think many people look at a wall stretching away from the internal structures and call it flare.  From the outside it looks identical, but in terms of how you’d address the problem, they’re very different, and in terms of what’s happening to the internal structures they’re very different too.

If a wall is simply thicker than it should be, you’re unlikely to do any harm removing the excess and making the wall straight again.  I should point out, that while it’s not doing harm, and it is likely to improve the look of the hoof from the outside, it’s not necessarily addressing the problem either.

If the wall is the same thickness all the way down, but bending outwards or stretching away from the internal structures, noticeable by a stretched white line, then trimming the wall so it’s straight is making the wall much thinner than it should be.  This means you’re making the wall weaker, where it’s already weak.

Flare will only stop growing when the stimulus for it to grow has been removed.  

Seems a facetiously obvious thing to say, but none the less it gets regularly overlooked, as obvious things often are.  Anything that’s happening in life will only stop happening when the cause has been removed.  Simple concept – can’t fail… except for the part where we need to define the cause that is…

There is a school of thought that suggests that flare grows due to the pressure caused by the thickened wall.  This means flare is causing the flare.  If this is true, then removing the flare will indeed stop it from growing back.  By removing the flare, you’ve removed the stimulus for more flare.

But…  If flare is the cause of flare…  How did the flare start?  There has to be a primary cause for the flare to develop in the first place.  This means that removing the flare is, at best, removing the secondary cause of your flare.  You’re still missing the first piece of the puzzle.  You’re treating a symptom not a cause.  (and I remain unconvinced that flare really does cause flare anyway)

Considering that trimming flare away is fairly hard work and treating symptoms, while often necessary, is a little like chasing your tail, I’d much rather find the primary cause, and deal with that.  It can be a little more frustrating for the brain – but so much easier on the back…

Hoof Growth 101 – Pressure stimulates growth

If pressure stimulates growth, and you have more growth than you want, then you have more pressure than you want.

So what causes too much pressure in or on a hoof capsule?

If it’s internal pressure, the pressure is coming from too much fluid in the foot.  That could be odema (poor lymphatic drainage) or blood (poor circulation).

If it’s mechanical, then it means the hoof wall is too thin to take the mechanical pressure.  But as I’m talking specifically about flare here, and flare is a thickening of the hoof wall, then it doesn’t seem like mechanical flare is a realistic option.  There’s no way to have a too thin thickened wall.  (rejoice one and all – mutually exclusive problems!! yay!!)

And if mechanical pressure isn’t a realistic cause, then is a mechanical intervention (ie trimming) a realistic solution?

Seems like we’re coming back to good old internal health again.  Everytime I try and think through a problem I always land back here!  Isn’t that how recurring nightmares work!!! 🙂

Does the mechanical stimulation from the rasp trick the hoof into thinking that it is wearing away fast and therefore the hoof grows faster resulting in more flare?

I don’t think so.  I don’t believe that the rasping stimulates much of anything in the hoof.  The amount of time the hoof is rasped for is fairly small.  Maybe 10 minutes out of 6 weeks?   Compared to the amount of time the hoof is being weighted, walked on grass, sand, tarmac, concrete, stood on rubber, shavings, etc the rasping is negligible.

I think the hoof responds to the forces that act upon it.  To me those forces include, but aren’t limited to, blood flow – which will include nutrition, toxins, hormones, hydration, pH etc not to mention restriction of blood flow, lymphatic fluid (builds up while horses are stood in stables), ridden work, turn out, standing still, playing, limping if lame, uneven pressures if compensating for any sort of stiffness, discomfort or conformational abnormality, shoes, boots, hoof balance, weather, uneven ground, hills, concussion, hoof landing patterns, gait abnormalities and many more…

There’s no research into this particular issue, but I’m not sure how you’d even go about researching that.  You’d have to remove all those other variables…  It would be complicated, for sure.  Probably complicated enough the results wouldn’t be very useful.

My opinion:- no the trimming of the hoof doesn’t result in more flare – if we’re defining flare as a thickening of the hoof wall.

But – if we’re talking about the wall stretching away (which is also bending the hoof wall) from the internal structures, then thinning the wall by removing the ‘flare’ would be weakening the wall where it’s under the most pressure, which would cause more bending of the wall.  This will make the hoof look more ‘flared’ from the outside.

Which leads us very nicely in to:

Is there any evidence to suggest that the mechanical separation at the white line caused by not trimming is painful for horses?

This mechanical separation of the wall from the internal structures is viewed from the underneath of the foot as stretching of the white line.  When stretching of the white line becomes very serious, we call it laminar wedge which means founder – the laminar attachment between the hoof wall and the pedal (coffin) bone is failing.

To me, this isn’t flare.  It’s looks very much like flare when you look at the outside of the hoof wall, but it isn’t flare in my  mind.  The reason I keep these things very separate in my mind, even though we’ll end up back at health of internal structures by the time we’ve talked this through, is because if you trim it like flare, you’re going to make the problem worse not better.

Unfortunately it is possible for the wall to thicken and stretch at the white line at the same time.  I’m sorry about that, it doesn’t make it easy for the purposes of identification, but I don’t make the rules, so I can’t change that.

What I will do is talk about the separation as if it’s not happening with thickened wall to make it easier to understand, and you’ll just have to remember that the 2 problems aren’t mutually exclusive.  Sadly not many problems are mutually exclusive (see my earlier rejoicing over too thin and too thick wall).

In fact, it almost seems churlish to call flare a problem.  It’s extra thickness to the hoof wall.  A bit of extra structure isn’t a huge problem…  It means you need to trim more off, or maybe your hoof boots or shoe doesn’t fit as your next trim/shoeing date approaches, but compared to very thin, collapsing walls, or failing laminar…

Stretching White Line

I’m not aware of scientific papers that prove that mechanical stretching of the white line is painful.  This doesn’t mean there aren’t any – if anyone knows of any please post the link in the comments box below.  I’m equally unaware of any papers saying that it’s not painful either.

I personally doubt how significant mechanical forces alone are in creating separation.  I feel that you need some internal inflammation of the laminar to cause separation.  I think with healthy internal structures, the hoof is strong enough to withstand the mechanical forces applied to it.

Stretched white line is often seen in retired horses, arthritic horses, lame horses, you know, horses in very little work.  If mechanical forces alone are the primary cause of the hoof wall stretching away from the internal structures, then it would stand to reason that most cases would be seen in show jumpers and 3 day eventers.

Surely it would be unheard of in horses just mooching about the pasture, whose most stressful event (in terms of pressure to the hoof capsule) was trotting across the field to greet their owner for a cwtch, a scratch and a feed.  Yet it’s the other way round.

Now’ inflammation in a horse with arthritis – that’s high.  Arthritis is an inflammatory condition after all.  One that causes increased mechanical stress on the hoof – true.  But I don’t think restricted movement in a joint causes more mechanical stress to the hoof than jumping a 5ft jump or banging round Badminton.

Which means mechanical stress is a problem, only when there is inflammation present.  Which means it’s the inflammation that is the problem that needs treating, not the mechanical stress.  Though obviously it tells us that when inflammation is present, you want to try to reduce mechanical stress.

Now, in terms of the question: Is there any evidence to suggest that the mechanical separation at the white line caused by not trimming is painful for horses?

I’m not sure that not trimming is in fact a cause of  mechanical stress.  When I’ve trimmed horses abroad who get no lush grass, mostly dry dirt paddocks, if they get turn out at all, they don’t get flare, or separation.  The hooves just get taller and taller, like coke cans.  The separation isn’t there.

Inflammation, which causes separation can be painful, whether the increased mechanical stress contributes to that I’m unsure, but here’s an observation based on my experience.  When trimming a horse with stretched white lines, I don’t think I’ve ever seen them more comfortable from relieving the mechanical stress from the leverage on the wall.

If I get the trim right, then they’re about the same after the trim than before it, which is why I don’t think the mechanical stress is more significant than the inflammation when it comes to what’s causing the discomfort.

I’ve never seen them improve from relieving the leverage on the wall – which could be taken as a slur on my trimming abilities  I suppose (can I slur my own abilities?!?!?).  I have seen their comfort increase dramatically from environmental interventions, with no trim applied at all.  Which again suggests the inflammation is more significant that the trim or lack thereof.

I would still relieve the leverage on the hoof wall where necessary, to reduce the stretching on the laminar, and help the attachment grow through tighter, but the question was is it causing pain.  I don’t think the mechanical stress in itself is causing pain, but it is likely to be perpetuating the problem of the wall being pulled away from the internal structures.

Wow!  That got wordy, I hope that helped Jess!

What do you think?  Has that given you some answers, or prompted more questions?
Put your 2 cents in and tell me in the comments below or on the Facebook or Twitter page.


The Healthy Horse: Feeding and Nutrition

We Are What We Eat

It's easy to see why diet is so important. The body is always regenerating, it needs good nutrition to be able to build healthy cells. Nutrition is such a confusing subject though!

There's so much advice, and so many different choices, how are you ever supposed to figure out what's right for your horse?

About the author

Debs is a practicing Equine Podiatrist with over 15 years experience, author, and educator.

She’s here to show you how to simplify your horse’s management painlessly so you feel in control and have a straightforward system that works for you.

When she’s not working you can find her playing with her own horses, watching geeky sci-fi or baking epic cakes.

  • Excellent article! Sound reasoning applied to thorough knowledge of underlying biological and biomechanical principles.

    • I haven’t seen your horse. I couldn’t possibly tell you what the cause is.

      Find the cause then remove the cause = solution

      There is no one singular cause or singular solution.

      This isn’t a article on how to trim your horse. It’s simply trying to help you understand what might be going on, so you have a better idea where to look for the problem. Sorry it didn’t help you

  • May I recommend that you look into excess or “pooled” bar material with regard to flare? They go hand in hand. A long hoof wall means long bars. If the bars are neglected, they “pool” under the ground pressure and begin filling the hoof capsule with excess material, this leading to the flares.

  • My horse has EMS VERT ACUTE AS HE GAS TO BE MANAGED TIGHTLY. NO PASTURE HAT TESTING 10% or less WSC and starch. Nothing with sugar. Supplements or grain all low or no sugar. Still each summer he sinks I do my best keeping flares down and trimmed to optimal every two weeks in summer. He has stretched white line. Gains concavity in winter sinks in summer.

  • Can you clarify for me When you say you’ve never seen them improve from relieving the leverage on the wall are you talking about stretched white line or pain? Because then you go on to say you do reduce leverage to reduce stretching…
    And how do you reduce leverage?

  • My mare’s unshod back feet stopped flaring (or stretching?) after I took her front shoes off. That suggests to me a big change in the way she is moving and also some mechanical impact, even if nutrition and exercise are key.

    • The same happened to my mare, though I think that was due to the changes I made, and I had a different hoof care practitioner. One who thought all 4 feet were equally important 🙂

      It can change the whole way they hold their body though. Interesting isn’t it 🙂

  • I agree with most of what you say, however, after trimming my two thoroughbreds for several years now I know their feet pretty well.

    Both had very thin walls, thin soles, contracted frogs, no heels, long toes and flares.
    So the pressure was on me when my trimmer stopped working due to pregnancy.

    I went very slowly on both when trimming just making sure I kept the walls off the ground with a mustang roll. Everything improved except the flare on the eldest, which was the one that had been shod the longest and been in flat racing the longest. the flare only improved when I removed the cause and it was the Bars that were that cause. His bars on the one hoof that had the worst flare were flattened and growing into the sole and towards the outer hoof wall. I also noticed that he weight beared on that front leg the most, both when grazing and when ridden. This weight bearing was the cause of the bars to grow into the sole outwards. I kept the bars to the correct angle and the flare improved dramatically so that now I hardly have a flare to rasp at all.

    They both have white line separation in winter only. I have put this down to them being in soft ground, therefor not receiving the normal pressure or wear on the foot. If trimmed weekly during this wet weather the walls are receiving the stimulus they require and do not separate.

    I would like your opinion on my observations.

    Regards Lesely

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