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Hoof Markup How-To (Image Intensive)
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AdamTill
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 Posted: Thu May 14th, 2009 12:05 am
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Hi folks,

Haven't had time to catch up on the threads lately, since I've been off at a wonderful clinic playing with horses. I did catch a request somewhere in there to explain what the lines on my markups mean, and I thought a step-by-step would be easiest there. This will be image intensive, but I'm hosting the photos elsewhere, so it should work out okay.

Okay, step one is to take photos of the hoof in question. There are two main ones - square on the side, and square on the bottom. Not "sort of square to the side because it's muddy" and "well it's sort of the bottom", but camera on the ground for the first one, and absolutely flat to the hoof for the second.

Next, resize the photos so that they're the same size. I use the extreme toe and the heel bulbs as reference. Rotate the sole shot so that the horizontal passes straight through the midline of the hoof.

I'm doing this in AutoCad by the way, but with a little playing you could even use a photocopier and drafting tools to do this the old fashioned way. Takes me about 10 mins per markup, but I'm on autopilot by now after a few hundred.




Next, draw a line that runs along the hairline from dorsal wall to heel. This is my Icelandic, and hair is an issue, but I've done this guy before so you'll have to take my word that the hairline is about right.

Find the spot on the outer (dorsal) wall, and draw a line that catches the first cm or two of growth. This is the spot that's most likely to represent the actual growth angle of the coffin bone (though not 100% of the time).


AdamTill
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 Posted: Thu May 14th, 2009 12:13 am
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Take your hairline, and divide it in half. Next, take that half of a line, and divide it again into thirds. The outer third is about the distance from the outer wall to the coffin bone dorsal wall, the middle third is the distance to the center of articulation (more on that later).

This is an old trick I pulled out of an AFA journal, and after a bunch of comparisons against xrays, it's pretty darn close as an approximation! I'll show some xrays later to show what I mean.



Draw a line from the true tip of the frog to the middle of the toe at the white line. Two caveats - try to find the actual tip of the frog, and the spot where the sole meets the inside edge of the white line.

The frog often overgrows at the tip, so dig around there with a hoofpick to get an idea of where the frog tip meets the sole.

For the actual edge of the white line, try to take into account any stretching due to lamellar wedge (I can explain that more if folks are unsure). If you don't, you'll get a more conservative trim, but won't make as much progress.

Divide that line in half. That's roughly where the tip of the coffin bone meets the centerline of the hoof.

Connect that line to the hairline as shown (the 1/3 mark). That's roughly the dorsal wall line for the coffin bone inside the hoof.

 

AdamTill
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 Posted: Thu May 14th, 2009 12:24 am
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Draw two more lines parallel to the one you just drew.

The green line is where the outer wall would be growing if it was perfectly connected. Any junk external to that is flare - here's a good example of what happens when you raise an Icelandic on rich pasture (he's been on a diet since I bought him 6 months ago, needless to say).

The pink line will make more sense later.



The solar plane of the coffin bone in a healthy foot is roughly 55 degrees from the dorsal wall. That changes horse-to-horse, but this is a good guess without rads. Use 65 degrees for a grade 1 or 2 club foot (TRUE club, more later).



As for how far to draw that line from the bottom of the hoof, use the collateral grooves as an example (those are the groves that run between the bars and the frog).

I have a little tool that marks off a 3/4" increment, then little bars that are an extra 1/4" long each. Most horses need about 3/4" of concavity at the tip of the frog (measured as depth compared to the sole at the edges). That means that my little gauge should sink up to the edge of the big 3/4" line. Most horses have WAY less than that, so the coffin bone at the tip is too close to the outside world.

Depth of the groove at the heel should be about 1/8"-1/4" more, so 3/4" to 1" deep.



Above bottom right is my gauge in action (this is two photos spliced, since I don't have three hands!). You can see that the green line that joins the 3/4" markers is at a huge angle (18 deg) from the actual ground line of the hoof. That's showing how far the coffin bone is tipped up, which is mirrored in the rads of the same hoof.

The other point to see in the above photo set is that the collateral grooves show just how deep the coffin bone is in the hoof. You couldn't possibly trim this very sunken hoof back into shape in one go, since the coffin bone needs to resuspend FAR higher in the hoof before that could happen. Does show how badly out of balance this hoof is, though.

Use the grooves and you'll never hit blood accidentally (save an abcess or something odd).

Last edited on Thu May 14th, 2009 01:16 am by AdamTill

AdamTill
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 Posted: Thu May 14th, 2009 12:32 am
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Back to the markup. Find the widest part of the hoof, or if the foot gets trimmed often like this one and the outer wall isn't all there, find the bridge of the hoof. If you don't know that term, it's roughly 3/4" back from the tip of the coffin bone.

Draw a line through that point, perpendicular (90 degrees) to the midline of the hoof (it's the new yellow line). Bring it up to the side shot.



From the point where the first line you drew on the sole shot meets the side shot, draw a line that's perpendicular to the solar line of the coffin bone. Continue that line to the point where it meets the blue line showing the dorsal wall of the coffin bone. That's about where the upper extent (extensor process) of the coffin bone lies.

The method here is that if you were to drill a hole through the bridge, you'll just clip the extensor process of the coffin bone.

In an ideal world, that point should be up at the hairline. If it isn't, the coffin bone is sitting too low in the hoof capsule. That's called distal decent.




AdamTill
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 Posted: Thu May 14th, 2009 12:38 am
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To find the proper groundline of the hoof, draw a line that's roughly 3 degrees from the bottom of the coffin bone (about right in a standing horse). Much more then that is probably rotated, and much less is probably negative plane.

This hoof was only trimmed a couple of weeks before this photo, so it's about right.




DO NOT INVADE LIVE SOLE TRYING TO GET THIS ORIENTATION. If your coffin bones are too low in the capsule, you'll never carve a healthy hoof out of an unhealthy horse. You need to see the future plane of the coffin bone, and let the bone resuspend itself naturally through movement.

Also, dropping heels too quickly can damage tendons.


AdamTill
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 Posted: Thu May 14th, 2009 12:44 am
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Most healthy hooves have a bit of toe rocker, which you or your farrier can add if you're comfortable and competent enough to do so.

To see that, find the spot where the line of the dorsal wall of the coffin bone meets the ground line. Draw a line from that point which is 10-15 degrees different from the groundline. Note that this is conservative - NB principles use about 1/8" from the ACTUAL tip of the coffin bone, not the projected tip at the groundline.




Find the spot where your green "true outer wall" meets the ground line. Set breakover back by relieving all excess wall from ground contact. I trim often, so I don't bother to thin the outer wall, but working in the lower 1/3 of the hoof capsule can extend a trim.



Mark the actual outer wall in red. The bit between the green and red lines is flare, or lamellar wedge. It will grow out if the hoof is fed, excercized and trimmed properly (in that order of importance).

 

Last edited on Thu May 14th, 2009 01:35 am by AdamTill

AdamTill
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 Posted: Thu May 14th, 2009 12:55 am
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Tindur was standing under himself a bit when I took the photo, so this might not be obvious, but you can evaluate the pastern angle if your horse is standing natually. I don't try to ever force a pastern angle, but use it as an indicator for how healthy the situation is.

Draw a line from the point where the yellow line intersects the ground line through the middle of the pastern (trust me here, there's hair in the way). That's the line of force as it passes down the hoof, and it will always come out somewere between Ducket's dot and the bridge.

If you compare that (orange) line to the yellow line (an extension of the pink line we drew earlier), you can see the change in the pastern angle compared to ideal. If the pastern angle is correct at rest, the lines should be parallel (ie not meet at an angle). As is obvious, it helps if your horse is standing squarely here.

Also note that I've approximated a symmetrical coffin bone shape on the sole here. It should become obvious that this is a left foot, and you can see how the distribution of area backs that up.




Here's a better example, where Tin was standing more natually (he's the far right hoof). You'll see how the yellow and orange lines almost line up, showing about the right pastern angle.



I used the example above to show someone how misguided they were in whacking off a bunch of heel from what is obviously a club foot. They misread how the coffin bone was shaped, and tried to trim the foot as if it wasn't clubbed (they assumed that it was as the blue shape, when it's actually probably more like the orange).

In a club foot, the COFFIN BONE IS A DIFFERENT SHAPE. You'll note from the before and after shots that the pastern angle is completely unchanged, and force is still passing down the limb in the same way it was before. The body is completely unable to support the trim, so the poor horse can't even load that heel. Horrible, horrible trimming mistake  the've actually created a negative plane coffin bone situation.

Compare that to my example of trimming a club. If you assume that the coffin bone is the blue lines, the trim makes no sense, yet it clearly works for the horse. If you realize the coffin bone is a different shape (go to vet literature for the backup here, if you'd like), it all becomes clear.

Last edited on Thu May 14th, 2009 01:25 am by AdamTill

AdamTill
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 Posted: Thu May 14th, 2009 01:02 am
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Here are a few examples. First, a founder, where the markup showed a 17 degree rotation (verified as 18 degrees on xray). Trimmed and fed properly, the pony was jumping 3 months later.


Here's a blowup showing pastern angles better. Note how the coffin bone is designed so that the line of force passes through the center of the ground plane...natural design in action.

Note that I drew the hairline too low on Tindur's photo below, before I remembered to account for feathers. This shows no distal decent (extensor process at hairline), where the markup we've been doing together shows a bit more.


For those that want to see if this works on a real foot, here's three shots of the same cadaver (the two sides are mirrors of the same hoof, one taken from each side). The method above shows you exactly what's inside.



Last edited on Thu May 14th, 2009 01:29 am by AdamTill

AdamTill
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 Posted: Thu May 14th, 2009 01:07 am
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Finally, the reason why the collateral grooves are so important again. Founder horse, rotated in all four. The difference here is that the rotation was in reverse, where the tip of the bone stayed about in place, but the extensor process fell inwards into the hoof (picture a reverse founder)

The standard landmarks fail and the markup would be deceptive, but checking the grooves always works. The depth of sole from the bottom the collateral groove to the coffin bone has been proven in vet literature to be a constant thickness - use that info.



Same thing, hind hooves. Someone was wondering about negative plane hinds...here's an example.




Time for bed. Hope this is what folks were looking for. I'll try to catch up on the threads later.

Tammy 2
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 Posted: Thu May 14th, 2009 11:13 am
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Wow Adam, thank you so very much for posting this !!!

What clinic did you attend ??

Tammy

 

 

Val
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 Posted: Thu May 14th, 2009 11:34 am
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Adam, you are awesome!

AdamTill
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 Posted: Thu May 14th, 2009 01:33 pm
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Thanks folks, glad it's useful. Tammy - can't actually post the name of the clinician, since she's not on the approved list.

Here's another example of using the collateral grooves to balance a hoof. When I was asked to look at this horse (same one as the sunken hoof above with the 18 degree standing angle), I could see why the farriers were having trouble with his hoof before. Not only was it sunken, but the heels were badly sheared, and were tending to go wry. Fairly straightforward case with the right tools, but those hadn't been used for a long time.

As above, the heels are high, but I don't correct more than 1/4" per trim. That way, I'm not endangering anything else in the body with too drastic an alteration.

On the photo below, I've marked a series of black lines. The top black line is a collateral groove depth of 3/4" which is where I would have like to have reached eventually, if possible. Each mark is an additional 1/4".

The heels are a mess due to an old injury (wire fence), and there is a fair amount of sidebone. Judging this balance visually is enough to give you a headache, but with a reference to the internal structures, it's not bad.

The trim used the future plane method above, with the added twist of needing to rebalance the heels to equal lengths. You can see how long this horse has been out by the fact that the heels stay put when unloaded, but load equally under pressure. By establishing the future plane of the heels, the reduced heel is slightly floated when standing, but will be loaded equally as the horse lands. Remember, this is the plane of the heel as it should be, so what it looks like at rest isn't terribly consequential.

Situations like this are tricky, since too much change at once can fracture the sidebone ossifications inside.



To my eye, the 3 degree rebalance still looks like it might need to go further. Looking at the xrays however, it shows a 3 degree opening angle between the coffin bone and short pastern, which means that the 3 degree change is all that was needed. Good old collateral grooves in action again!



Unfortunately the critter above didn't get to enjoy his new feet for too long. In a few months he was happily running around his pasture, but then his owner decided to shoe him in order to get a jumper trainer to work with him.

I don't shoe since I don't do this full-time, but I suggested a NB farrier be found. There are none in town, but one was found that said he could do the job (sure...). He obviously thought the toes were too long, so lopped a bunch of vertical toe height off before applying shoes and sole pack, and using a wedge pad to undo all the heel height reduction which had been working so well. Also undid the lateral rebalance, just to be sure that everything went back to the way it was before. Predictably, he drew blood at the tip of the coffin bone, and the horse was absolutely miserable.

Sigh.

I took the before photo the day before he was shod, since I was curious how this was going to work out. I wasn't there for the shoeing, which for the farrier's sake was probably good. Red line shows the junction between the pad and hoof, green line between pad and shoe.

 

Last edited on Thu May 14th, 2009 02:24 pm by AdamTill

AdamTill
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 Posted: Thu May 14th, 2009 02:48 pm
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Last ones and I'm done unless folks want anything else.

Straightening heel tubules by bringing back breakover. This horse maintained his heels on his own, but making sure to keep those back helps as well if they don't do it on their own (my Icelandic's don't).



Visual on what lamellar wedge looks like from the inside. Healthy horse on right, recovered founder on left (other photos are above in the negative plane example).

The pink lines show the inside edge of the white line, and the yellow lines show the thickness of the outer hoof wall. That means that the distance from the inner yellow line to the pink line is the "white line", and that everything inside that is either true white line as in the right photo, or displaced inner hoof wall material (ie lamellar wedge) as the hatched area shows on the left.

This is what I meant by "find the inner edge of the white line"...the pink line. The rocker can start from that line, and still be very conservative.


Last edited on Thu May 14th, 2009 02:49 pm by AdamTill

RobVSG
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 Posted: Fri May 15th, 2009 08:58 pm
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WooooooW!!!!! To say that that this info is priceless would be a huuuuuge understatement. Now if some of us can just put this into good practice.

Thank you very much for sharing Adam.

One question I have. I see how you determine the front side and bottom side of P3, and the top tip,  but the back side(3rd blue line) What angle does it come in at???

Most concise way I can think to ask ...is P3 overall isosceles (55*, 55*, 70*) or scalene (55*, ??*, ??*)   ????

I apologize if I missed the obvious. And come to think of it, that side may not be relevant to anything, I just felt like I was missing something there.

Thanks,

Rob

Last edited on Fri May 15th, 2009 09:01 pm by RobVSG

AdamTill
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 Posted: Sun May 17th, 2009 12:31 am
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Hi Rob,

I know exactly what you mean, and my answer is that it's a bit of an approximation. In reality, that line is fairly arbitrary, and just makes it easier for folks to see the coffin bone. As far as I know, knowing how far back the wings of the coffin bone extend isn't useful info while trimming, but I could certainly be wrong.

It's a bit like judging sole thickness from photos - there's some guesswork involved.

Cheers,
Adam

BTW - when I said the bridge was about 3/4" back from the tip of the coffin bone, I meant tip of the true frog. Typo.


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