Part 4 of Equine Foot Balance

In our last talk, we discussed how the dysfunctional loading of the upper body will affect the limb's loading and distal joints and that there has to be a neuromuscular response to these biological changes.

But how does that dysfunctional loading cause a change in the shape of the limb's distal structures, especially the equine foot?

It all comes down to the structure's tensile strength, its ability to carry and distribute a load, and the concessional forces of contact with the ground through the hoof capsule and ascending to the upper body.

When we look at it from the engineering point of view, we find that the dome structure requires its base or ground level to be supportive if it is to carry large amounts of weight through its centre. We also know that if the weight or loading forces are off-centre, the dome will sustain structural dysfunction and experience an upset in that structure's loading and shearing forces. The dome structure needs this design to be functional and maintain its constant shape when pushing on the ground and meeting these static forces. The engineers know the dome shape can be reinforced to carry these off-centre loading forces by adding extra reinforcing to its base, especially on the side experiencing the most compressional forces. 

The hoof capsule is no different, as it acts as the supportive structure or support beam for our dome, the pedial bone. When the forces on the pedial bone are not neutral, the body's way of enforcing its supporting structure of the hoof capsule is to add more structure first: it lays down more hoof structure by thickening its walls and then the base by adding more sole and/or a callus to the area of concern.

We see this every day in our equine feet, where the dorsal wall is thicker in one area than the other or the sole is thicker on one side more than the other. We also see the effects of structures like the sole and hoof capsule going beyond their structural capabilities when they have reached the tensile strength of that structure. Now, they move into the shearing stage as they cannot cope with the dysfunctional loading forces. You have all seen the dysfunctional white line, the sole pulling away from the white line, the flares on the hoof capsule, cracks in the external hoof walls, the pitting in the soles of the feet and the list can go on.

They are all signs that the biological structure has reached its limits of loading forces and is experiencing changes in its tensile strength and has now reached the shearing phase, and the structure has lost its structural integrity and ability to maintain its functional shape. The equine pedal bone is designed by nature to withstand the forces the horse faces every hour and every day, but when things go wrong or we decide to change the loading forces, the equine is pushed into biological changes that affect its loading forces and are seen in the shape of the external structures.

These same principles of engineering prevail in nature, as you can now start to understand. I would ask the question why we still think we need to change the laws of engineering and physics by requiring the equine pedial bone to be set at an angle of three to five degrees positive. It goes against all known principles of load-carrying structures to have a loading force that does not match the base of the structure.

In our next talk, we can examine other supporting structures of the distal interphalangeal joint and their complex loading properties while allowing the structures above the mobility to adjust to the terrain on which they have to work and support the body.   

Dysfunctional upper body loading will affect the loading of the distal joints.