BACK TO BASICS: LAMENESS AND PODIATRY


should not be applied long-term because damage to the hoof wall is thought to occur from the heat gen- erated by the composite, and they have been shown to decrease expansion at the heels.18 Farriery for low heel conformation is often based


Fig. 10. A, A Colleoni® shoe with a heel plate and impression material across the palmar foot. B, A steel shoe with a spider plate that will redistribute the load across the solar surface of the foot.


steel or aluminum flat shoe with a wedge pad can be used to achieve the desired heel angle. Depending on the severity that the heels are damaged or com- promised, a load-sharing effect can be accomplished by using a straight-bar shoe with a pad or degree pad placed between the shoe and the foot. The author is reluctant to use a heart-bar show if the frog and digital cushion lack sufficient structural mass. An open-steel or aluminum shoe with a heel plate welded between the branches of the shoe or a plastic bar wedge placed between the shoe and the foot can also be used. Holes can be drilled in the heel plate or bar wedge and some form of silastic material placed underneath the plate or wedge to create a deformable interface to spread the weight- bearing function over all the structures in the palmar foot. The same effect can be achieved by placing a “spider” plate between the shoe and the foot. Impression material is placed on the ground surface of the palmar foot, starting in the middle of the frog and extending palmarly as far as desired. The shoe and pad or plate are placed on the foot, and the heel of the shoe is pressed into the impres- sion material, forming a slight wedge. Two nails are placed in the toe of the shoe and the foot is held off the ground until the impression material cures (Figs. 10A and 10B). Glue-on technology may be helpful to improve the structures in the heel but


on trial and error and combinations of various meth- ods but depends on assessing the structures present, the footing, the athletic pursuit of the horse, and client expectations. Any form of farriery for LT-LH should be accompanied by enhancing breakover. Moving breakover palmarly can be accomplished in a variety of ways, such as rolling or rockering the toe of the shoe or creating a rolled toe in the shoe by using a hand grinder where the breakover begins at the inner branch of the shoe. Moving breakover palmarly/plantarly decreases the moment applied to the DIP joint and appears to decrease the maximum tension in the DDFT, which occurs toward the end of the stance phase at the beginning of breakover (Fig. 11).1–7


6. Upright or Clubfoot Conformation


Flexural deformities have been reported as a cause of decreased athletic performance and chronic low- grade lameness in the mature horse.19–22 A club- foot is defined as an upright conformation of the foot associated with a flexural deformity of the DIP joint.19,21 It is characterized by a broken forward HPA, which is a reflection of a hoof capsule where the angle of the dorsal hoof wall is higher than the angle of the dorsal pastern. This broken forward HPA or flexural deformity is created by some degree of shortening of the musculotendinous unit (DDFT and associated muscle bellies), causing the DIP joint to be drawn into a flexed position. Biomechani- cally, as the tension in the DDFT increases, the COP moves dorsally in the toe (Figs. 12A–C).19,22 Examination from the lateral side generally re-


veals a broken forward HPA, the coronet assumes a more horizontal position, poor hoof wall consistency, a disparity of hoof wall growth with more growth at the heel than at the toe is generally present, and there will be some degree of a flare in the dorsal hoof wall. Looking at the ground surface of the foot, there will be disproportionate ground surface on either side of the widest part of the foot, with the palmar section showing less surface area, a thin


Fig. 11. Shows the biomechanical effects of moving breakover in a palmar direction. 358 2018  Vol. 64  AAEP PROCEEDINGS


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