Proper hoof trimming has been my weakest area over the years.

A kind and generous farrier named June contacted me in May 2013 and not only helped me see the flaws in Robin’s trim but also helped me locate some resources for getting up to speed quickly on hoof anatomy.

I have been riding since I was 6 and owned a horse continuously since I was 9, and it’s embarrassing to realize how little I’ve known about horse feet. But not for a lack of trying.

My main resources now, in addition to June, are the websites of farriers Gene Ovnicek and Pete Ramey. These names are not new to anyone. These two farriers are highly regarded resources for providing instruction to others.

Using their concepts, I’ve tried to assemble what I hope is a quick guide to understanding the healthy hoof, as well as the laminitic one, and I will update this with additional information as I learn it. For more information, click the links within the text to go to the original material.

Ovnicek’s Hoof Mapping Protocol

Ovnicek’s ELPO (Equine Lameness Prevention Organization) Hoof Mapping Protocol provides guidelines for assessing the foot. I am shortening his guidelines to give you some very simple principles, but you can find the full protocol by downloading the PDF.

This is a screen grab of Ovnicek’s mapping protocol. Click it to go to the full protocol.

I found it helpful to mark the bottom of Robin’s feet with a marker to learn all of these principles.

A properly trimmed hoof should have the same amount of hoof ahead of the widest part of the hoof as it has behind the widest part (or even 60 percent behind the widest part). Sadly, most horses have 60 percent in front of the widest part. When I started this, Robin had at least 60 percent of his foot in front of the widest part. This would put too much pressure on his toe.

To evaluate your horse’s foot:

Step 1: Find the widest part of the hoof.

For me, the following instruction has been the easiest way to do this:

Measure the length of the central sulcus, the dimpled area inside the frog, with a tape measure. Double that measurement along the frog to get the true apex, or tip, of the frog. So, for example, if the central sulcus is 1 1/2 inches, measure from the front tip of the central sulcus 1 1/2 inches forward on the frog to arrive at the true apex. Mark the true apex.

From the true apex, measure 1 inch toward the heel to get the widest part of the hoof. Draw a line across the hoof at this point.

Step 2: Find the tip of the coffin bone:

The tip of the coffin bone is approximately 1 3/4 inches in front of the widest part of the hoof. Measure from the line you drew for the widest part of the foot 1 3/4 inches toward the toe and draw a new line across the foot.

Step 3: Find the approximate point of breakover:

This is 1/4 inch in front of the tip of the coffin bone. Draw another line for the point of breakover.

If you’re looking for shortcuts when you’re working on your horse, you can find the point of breakover by measuring 1 inch in front of the true apex of the frog.

Step 4: Draw a line where the toe should end:

I was mistaken earlier in saying this is one gloved finger width in front of the point of breakover. The toe should fall just beyond the point of breakover. There doesn’t seem to be a fixed measurement here, but one gloved finger width might be a good maximum. Since we want the white line area to be tight, it’s counterproductive to let the toe get long and stretched.

Step 5: Analyze your horse’s hoof:

If you have a lot of hoof in front of the line where the toe should end, you likely have some work to do.

Ramey’s theories on the dissent of the coffin bone

Ramey has assembled a page on understanding how and why the coffin bone drops in the foot.

He says the coffin bone often drops in horses, particularly sport horses, due to shoeing practices that force the hoof walls to bear all of the force of impact, creating more constant stress than the laminae were ever intended to withstand. Ideally, the hoof walls, soles, bars and frogs are supposed to work together to support the horse. Thus, the descent of the coffin bone is not just a problem for laminitic horses.

Ramey says the coffin bone can return to the proper position by moving higher in the hoof relative to the coronary band if the sole is allowed to grow properly.

Here are some of his concepts:

The sole grows from the bottom of the coffin bone. That’s it. The term sole is used inappropriately in reference to other parts of the hoof. Any hard material in front of the tip of the coffin bone is “intertubular hoof horn produced from cells migrating down from the coronet with the epidermal laminae.” It’s not sole. That intertubular horn should not be there. The coffin bone should be attached to the hoof wall.

Ramey says all horse hooves are very consistent in their distance from the bottom of the collateral grooves (along the frog) to the bottom of the coffin bone, so we can use the grooves to judge where the coffin bone is inside the hoof without radiographs.

He says to put a rasp or ruler across the bottom of the hoof. Using another measurement tool, measure from the rasp or ruler to the bottom of the collateral groove at the tip of the frog and again from the rasp or ruler to the bottom of the groove near the heel.

In healthy hooves, this measurement should be around 3/4 inch at the tip of the frog and 1 inch toward the heel.

If this measurement is only 1/16th of an inch at the tip of the frog, the coffin bone is very close to the ground.

I personally find this measurement technique almost impossible to pull off, but I do study my horses’ grooves, particularly in photos over time, and I grow more confident as the grooves get deeper.

For more about sole thickness, visit Ramey’s page on understanding the horse’s sole.

So, what to do about a dropped coffin bone? Don’t touch the sole when trimming. Especially, don’t remove any lumps in the sole. Ramey says the hoof will build calluses around the coffin bone as the horse tries to grow healthy sole, and farriers who trim this lumpy area in trying to create concavity are actually thinning the sole and causing the coffin bone to drop even more. The sole needs to be loaded and unloaded with weight to grow, so it needs to come in contact with the ground. When the sole becomes thick enough, it will drive the coffin bone higher relative to the coronary band. As this happens, the sole will become concave on its own, and this concavity will be appear all the way to the edge of the wall. The sole creates its own concavity. You cannot do this for it.

If there is flare in the wall, or a gap between the sole and hoof wall, this flared wall should be rasped off and the bottom of the hoof beveled, or sloped, from inside to out at 30 degrees, so only the inside of that bevel is touching the ground. If the hoof doesn’t have irreversible damage, this trim should allow the hoof wall to grow in with a tighter attachment. In the meantime, the horse needs to carry its weight on the sole rather than the wall and should be provided with boots with neoprene foam (according to Ramey) or insulation-type foam taped to the hoof (according to Ovnicek) to make it comfortable.

Ramey says he follows one big rule on how much to trim the hoof in the laminitic horse: He trims the walls and bars to 1/16th inch above healthy sole (assuming there’s healthy wall to trim), and lets the sole grow out.

Where I run into challenges is finding an appropriate heel height in Ramey’s principles.

I do understand that, in the perfect foot, the heels are low enough to allow the frog to touch the ground and expand and contract. Getting there is more challenging, since the laminitic horse often grows a ton of heel. How much can you take off and when, particularly if the coffin bone is dropped? I noticed over the summer of 2013 that every time I took Robin’s heels down a little bit, he was sore again, and this wasn’t due to the pull of the deep digital flexor tendon. What I believe is needed is the heel needs to be longer while you’re leaving the sole alone to push the coffin bone back into position. The hoof needs to be relatively level front to back. If you take the heel down, you’re lowering the heel too much and inflicting pain. You must wait until the sole becomes concave and then you can lower the heel to once again maintain a level foot.

With my new and still evolving understanding of the hoof under way, I now think passing a hoof quiz should be mandatory for anyone who wants to buy a horse.

Also, I should add, as I put all this knowledge into practice in the summer of 2013, I thought it was interesting, but Robin was too far gone to save. Nonetheless, I trimmed up his feet over several months and got them looking more normal. By November 2013, he was off bute and trotting and cantering. I am a convert. And, if I can do this, anyone can.