Trimming for Concavity/Vertical Toe Height

by Frances Guthrie ©2006

No, you can’t create a healthy, sound hoof by carving the solar surface into a concaved form. Nor can toe height be created by trimming the heels even shorter.

Yes, you can use trim techniques that will enhance natural hoof form—such techniques are so successful that you might be tempted to say you “trim for concavity!”

I want to jump right in and tell you about optimal toe length, strong heels, thick soles, the importance of rounding the hoof walls, etc. But first—let’s consider the importance of solar concavity, which is only present when the hoof has vertical toe height. A hoof won’t have one without the other! (Naturally, there are always exceptions, and this article is not about extremely contracted hooves with full soles).

The Importance of Healthy Concavity

Simply explained, a hoof widens when it is weighted; as the walls move outwards, the sole of a healthy, concaved hoof draws flat. (A little or a lot—depending on the hoof, terrain, gait and impact). It is believed that in the widening phase of hoof mechanism, the sole of a “flat-footed horse,” is actually impacted by the coffin bone, with possible bruising of the sensitive solar/frog corium. So concavity is important for comfortable hoof mechanism, and the absorption of concussion.

When the toe wall of the hoof is too short vertically, the coffin bone position relative to the limb, and the ground, is compromised. Therefore angles, impact, shock absorption, hoof mechanism, circulation etc. are all affected by lack of concavity and vertical toe height. When any area of the wall is too short, the sole is often thin in that area, as well—which can be of little concern, or develop into a serious pathology, with the coffin bone exposed.

The connection of the hoof capsule to the coffin bone and sensitive tissues and coriums, is commonly referred to as “coffin bone suspension.” It has been noticed that the coffin bone is quite high within the hoof capsule of the feral/wild horse, somewhat lower in the domestic horse, and the flat-footed, thin-soled horse’s coffin bone is very close to the terrain upon which the horse is walking! The white line connection is critical for soundness—and concavity is a great indicator.

Left: This horse could not gain vertical toe height; every time the heels were over-shortened to create a better hairline angle, the horse would overweight the toe due to heel pain, and thus continue a cycle of toe wear.

Right: Same foot, 8 months later. Adjusted trimming technique helped this hoof gain substantial vertical toe height; hairline angle improved, concavity developed, and horse was now sound. The cycle of toe wear was finally broken.

The Trim Techniques

It’s pretty simple, really, and I don’t mean to sound like a smart ass!

Keep the heels comfortable, back up the toes, and add a mustang roll. The hooves will develop concavity, the soles will thicken, the toes will increase in vertical height, the frontal hoof wall surface will grow in straight and strong without dishing, and the horses will begin to walk over the rocks!

Maintain comfortable heels! Do trim to encourage natural, heel-first or flat-footed landing. If the heels are strong and comfortable, the horse will move confidently, hoof mechanism and healthy circulation will be optimal, and the horse will no longer avoid weighting the heels. (Horses that are sensitive in the heel area tend to shift their weight forward, and may wear the toe wall excessively short—see photo example above).

Be cautious of trimming the heels, bars and quarters of the hoof really short to obtain “correct” angles that will match the short toe. A hoof trimmed in this way has a shallow profile, without adequate height for concavity. The thin sole in the heel/bar triangle (seat of the corn) may be sensitive on all but the most optimal of rehabilitation terrains.

This may also mean that you are unable to trim the bars lower than the sole. In photos of wild horse hooves, the bars are usually quite short, and passive to the hoof wall, but I have noticed that they do not appear to be lower than the sole. Often the difference between heel comfort or not, is simply a lighter bar trim for protection from the pebbles.

Watch those toes—and those flares. The hoof capsule is a “cast” of the coffin bone, produced by the various coriums. If the wall is permitted to flare, it pulls away from the coffin bone, reducing the integrity of the white line connection. Long toes are forward flares, and they pull the hoof capsule into an elongated form, stretching the sole. When the sole is stretched, it is drawn flatter. FLAT = less concavity!

Trim to ensure the hoof wall grows out to the ground, parallel to the coffin bone. This might mean rounding the wall more, or rasping a little higher than last time; for some hooves, it may take a number of trims, but that’s okay. But know that when the hoof wall grows in straight, without bulges, flares, or dished areas, it will have a much better laminar attachment, increased vertical toe height and concavity, too! You can measure the coronet/wall angle as described by Dr. Strasser, the “healing angle” of the new wall growth that Jaime Jackson refers to, or perhaps Bergy Bergeleen’s 1/3 measurement. They are all similar!

And, round the hoof walls—yes, use some style of a Mustang Roll. There is lots of rain where I live, and when I study the bottom edges of a naturally worn hoof wall, it’s rounded, too—not unlike those of the horses in drier terrains. I find that rounding the hoof wall is very helpful to prevent flaring.

Don’t forget the sole—trim for concavity, by NOT trimming very much sole at all! Yes, really! Cultivate a strong, healthy sole that will flex on weight bearing, stabilize the hoof walls and protect the sensitive sole and frog from bruising.

Sound horses MUST have good concavity. This photo is an example of how to evaluate your horse’s hoof concavity.

About the author: Former farrier and graduate of Dr Strasser’s certification course (2002), Frances incorporates the techniques of many popular barefoot trimming methods in her work. When she’s not consulting or trimming hooves, Frances is often found teaching natural horsemanship; her students learn to ride bareback and bitless—on barefoot horses, naturally!

This article was printed in issue 23 of The Horse's Hoof Magazine. To order your subscription, please visit The Horse's Hoof Store

©2006 by The Horse's Hoof. All rights reserved. No part of these publications may be reproduced by any means whatsoever without the written permission of the publisher and/or authors. The information contained within these articles is intended for educational purposes only, and not for diagnosing or medicinally prescribing in any way. Readers are cautioned to seek expert advice from a qualified health professional before pursuing any form of treatment on their animals. Opinions expressed herein are those of the authors and do not necessarily reflect those of the publisher.