Flat foot? Concavity and Health

Concavity, Conformation or Health?

By KC La Pierre

We often receive emails from horse owners exhibiting frustration over their inability to aid their horse in achieving concavity to their horses' hooves. Usually it is said that their horse is footie (tender over rough or hard ground) after months or even years of being barefoot. They go on to explain that they are frustrated, because they feel that they have been doing all the right things; created a natural environment, provided exercise, have addressed nutrition and done all of the other things that are said to achieve concavity and health to the hoof. Why then is my horse still footie over rough ground and why can't I get concavity!

The first objective when attempting to answer such an email is to determine the true conformation and the state of health of their horses' foot. Lack of concavity is not something that can be corrected by trimming, and a lack of concavity is not always the cause for a horse being footie (stay with me here). Concavity defines conformation and not health. Taking a simplistic view of the sole does not serve the horse. The sole, like the hoof wall cannot be viewed or treated as homogeneous (having the same make-up throughout). The sole is divided into two distinct structures, the Primary Sole and the Terminal Sole. Each is defined by its conformation and the property of its horn (tissue). The Primary Sole is the horn that has a foundation of bone (that part of the sole that covers the coffin bone). The Terminal Sole is that which has a foundation of cartilage and forms around the perimeter of the coffin bone. Being familiar with the "Hoof Wall Matrix" will help you to determine the current state of health of both the primary and terminal sole. As the health of the sole increases a matrix is formed creating a healthy transition from terminal sole to primary sole. This matrix is important to overall performance.

Terminal sole consist of horn that is made up of terminal tubules (tough horn that distorts without failure) and intertubular horn, terminal sole allows for needed distortion. Primary sole consist of primary tubules (hard horn that provides stability, resisting distortion) and intertubular horn. The function of each is determined by its foundation. The chief function of the primary sole is to protect the coffin bone (its foundation), not from concussion, but rather from torque (twist). The primary function of the terminal sole is to allow for distortion (also protecting the coffin bone from torque), and to provide protection from blunt trauma. In both instances the horn needs to be healthy, have depth, and have a strong matrix.

Lack of concavity to the primary sole in truth defines the conformation of its foundation, the coffin bone. It is not possible to increase this concavity. If there is little concavity to the distal dorsal (bottom) surface of the coffin bone, there will be little concavity to the primary sole. The Unified Sole Theory by Mike Salvoldi describes uniform thickness of the sole. However, concavity of the hoof capsule is not defined by the concavity of the primary sole. Concavity of the solar (bottom) aspect of the hoof does increase with an increase in the depth of horn of both the primary and terminal sole. Why? Take a look at the illustrations presented here. 

You will see that as the diameter and height of a concave structure increases the depth of the concavity increases (its center is further from its perimeter). The concavity (conformation) of the primary (center) sole does not change, but the conformation of the overall solar aspect does. The internal foot is in effect further away from the ground surface and better protected by healthier thicker horn.

Many of the hooves presented with lack of concavity are in fact exhibiting a lack of depth in solar horn and poor matrix to both the sole and hoof wall.

Is lack of concavity to the primary sole a cause for concern? Because function is determined by conformation and the property of a structure's tissue, a lack of concavity to the coffin bone can result in a diminished ability to dissipate the energies created during the stance (load) phase of the stride. Some horses can handle higher levels of energy and cope well with a flat conformation (within limits), where others are more sensitive to the energies resulting from a flat conformation. If your expectation is for high performance where the foot is exposed to high levels of energy, then conformation of this sort does become a concern.

How can we help the horse with such conformation? After all concavity cannot be returned to the coffin bone. As I mentioned earlier in this article depth of sole can be increased, that is if the conditions are right. Following two principles of Applied EquinePodiatry can help in developing a treatment protocol that can help in the development of a stronger hoof capsule (including Sole).

1.       Accepting that the horse does have the natural ability to heal itself, this provided the environment is conducive to healing.

2.       That correct force is the stimulus for correct growth

When examining environment you must take into consideration not only terrain, but also nutrition, exercise, and how the hoof is treated (balanced, trimmed/shod). 

Starting with a balanced hoof and exercising within the defined Spectrum of Usability for the horse are paramount to success. 

If you are dealing with less than ideal conformation of the coffin bone do your homework on foot function.

It is not possible to increase the concavity of the foundation, but it may be possible to increase the health of those structures that will supplement foot function.