Part 6 of Equine Foot Balance

Now that we know that the pedal bone and the navicular bone are engineered to carry the weight of the equine to the ground under their feet, we have to look at how the distal limb structures react to the ground forces pushing back and still allow the movement of the involved structure to absorb the concessional and loading forces of both the animal's body and the ground they have to travel over.

Two other structures are part of this absorbing process: the digital cushion and the internal bars.

These two concessional absorbing structures have been engineered by nature to form what we know as triangle shapes, with the internal bar sitting higher at the palmar aspect of the foot and sloping down to its apex dorsally, forming a triangle shape and allowing it to contain the similarly shaped digital cushion within its internal walls. It is when the load experienced by the palmar aspect of the foot is dysfunctional, the digital cushion and the internal bars will have their strength and ability to distribute weight evenly across the palmar section of the foot depleted because the angle of their triangle shape has changed through external forces.

When the fundamental shape of the internal bars and digital cushion changes, we see the 3D truss structure of the triangle lose its strong and ridged construction, and the angle of where its opposing sides meet can no longer cope with the applied forces; we see the structure breaking down.

It is the same with the internal bars and digital cushion of the equine foot, as they tend to lose their shape of angles and straight sides that allow for the lower palmar aspect of the equine foot and that determines the articulation of the distal interphalangeal joint and shape of the hoof capsule.      

When we have a lower palmar (back of the foot) aspect of the foot, we overload the structure as the ligament structures of the navicular bone. We see it move into a dysfunctional alignment within the distal interphalangeal joint. It tends to set higher on the articulation surface of the middle phalanx. This dysfunctional alignment means its loading and articulation capabilities are completely changed; therefore, other supporting structures must take up the dysfunctional loading.

Other structures like the distal cartilage are now dysfunctionally involved and have an extreme influence on the vascular and neurological information entering or leaving the equine foot, for when the distal cartilage is dysfunctional and implodes inwards on landing or incorrect postural stance, the biological properties of the distal limb changes and the upper body must compensate for these changes. These dysfunctional changes also provide the perfect scenario for underrun heels, reduced digital cushion, low internal bars and other issues leading to the forward migrating hoof capsule.  

The body's act of dealing with an imbalance in the animal's centre of mass and the projected centre of pressure on the ground alters the break-over of the distal joints and limbs. The biological trick of the dysfunctional body is to increase the structure's tensile strength or add additional thickness to the structure to prevent the deformation of its body parts experiencing dysfunctional or abnormal loading characteristics.

Now, we see the dysfunctional effects on the break-over and shape of the hoof capsule and the supporting structures as they change their biological characteristics. When supporting the dysfunctional loading of the distal interphalangeal joint, the body's biological response is to add structure to support the imbalance. Hence, we have our hoof capsule imbalance and a change in the tensile strength of the supporting ligaments, tendons, and cartilage, and these are the structures that we must learn to comprehend to ensure correct hoof balance for our horses.

For these reasons, we must ask ourselves how we are changing nature's design when we alter the angle of the hoof capsule with our farriering process.

I will finish this group of blogs by letting you know if you like my hypotheses on how nature has bioengineered the equine foot. Then, in my new book, Equine Biology-Based Farriering, you can read more about this fascinating subject in its pages, which will be out very soon.

The next blog will be an article on the hoof angles of the horse's feet and the importance and maintenance of proper hoof angles.  

Do you know the true angle of your horse's distal joints?