All I know is what I read in the American Farriers Journal; I didn’t get my copy in the mail so I had to confiscate one, here are the highlights:
In ‘Understanding Hoof Shape’ an article from the ‘Hoof of the Horse’ by Simon Curtis, here are some notes; “plastic deformation is the semi permanent change in shape caused by compression and bending of the horn. Hoof distortion is frequently a result of a conformation fault which caused an external influence upon the hoof capsule.” what he’s getting at here is that the weight of the horse over the foot has an equal and opposing force which is the ground. He goes on to say “Laterally alters stance and loading of the hoof capsule which in turn changes shape so that we no longer have a pair of hooves.” this is important and a lot of people don’t get this so let’s explore. Look at any horse from the front and notice the size and shape of the shoulders from one side to the other, one side is more developed than the other. The bigger side has more muscle-tendon length, let’s go on; “Tendon tension or the lack of it changes loading on the sole and hoof wall bearing boarder, pulling, bending and compressing horn.” So there you have it, Curtis described the three things that influences the foot; weight over the capsule, ground reaction force and how much lift or lag there is from the deep flexor tendon, BOOM. When you learn how to manage this through the line of action of center of rotation through palmar P3 is when farriery begins.
In ‘Shoeing for a Living’, farrier Kalan Blessing says he doesn’t use a whole lot of different shoes, he can modify what he has for the desired mechanics he needs. I guess that’s what hammers and anvils are for. If he has a bad spot in a foot he will shore it up with Superfast. This is a practice I use all the time with great results. Blessing says he would rather give a horse some vertical depth and then roll or rocker the toe. He says this makes the foot “happier”. He’s right on, the biggest problem I see is in feet is not enough hoof and it can’t roll forward.
In the article ‘Correct or Maintain’, Jacob Butler brings up some good points; each horse has it’s own conformation combination. Conformation influences growth and wear of the hoof. The shape and angle of the foot are the effect of the horse’s weight on the hoof. This is what Curtis was talking about. He says that the farrier could become the scapegoat of excuses or be blamed for something they have no control over. Sadly this is true as that is the first person to blame. This is why education, especially to you farriers is so important. When you can stand in front of a veterinarian and or owner and tell them in an educated way how the cow ate the cabbage on biomechanics of the foot, things will get real quiet. They might still fire you but that’s on them because they know that you know.
In Biomechanics there is an article ‘How Ground Surfaces Influences Performance.’ All of this is interesting but at the end of the day to survive different footings, a horse needs to be as balanced as possible.
In ‘A Step by Step System for Using Radiographs to Plan Shoeing’, Swiss shoer Stefan Wehrli transfers radiograph data to the foot. His guidelines: DP balance about center of rotation, break-over, palmar angles, sole depth and mediolateral balance. If he could have tied palmar angles into the hoof-pastern axis and moment arms about center of rotation, he really would have nailed it. One thing I really liked was that all of his case studies were shod in a rocker shoe.
In Doug Russo’s article ‘Beware, Radiographs Can Lie to You’, it is true that when done improperly radiographs can be misleading but when properly with paired limbs positioned at 90° on blocks of correct height with a wire on the foot surface, there is no better way to evaluate balance. Standing a horse on foam is going to forgive palmarodorsal, mediolateral and craniocaudal imbalances because the foot is going to give to the deep flexor pull. To balance a foot a person needs to reference ventral depths, break-over mechanics, the line of action of the tendons among other things. The palmar angle produced by a foot standing on a foam block may not be totally correct. How are you going to get these measurements to the foot? Are you going to shoe the horse on a foam floor? I appreciate Doug thinking out of the box but this doesn’t work.