LAMENESS EXAMINATION AND THERAPY


Historically, farriers have been taught to trim (lower) the heels to correct the distorted hoof capsule and promote weight-bearing in the heel area, but this type of trimming comes with a price. As the severity of the flexural deformity increases, so too does the shortening of the musculotendinous unit; therefore, lowering the heels directly increases the tension within the musculotendinous unit, and these stresses may lead to irresolvable tearing of the dorsal lamellae, widening of the sole-wall junction similar to that seen in the chronic laminitic hoof, and increased pain.18,19,25 The increased forces placed on the DDFT from this type of trimming also promote hoof capsule distortion and abnormal load- ing. Furthermore, if there is pathology present in the soft tissue structures of the palmar foot, decreas- ing the height of the heels is likely to place more strain in this section of the foot.


11. Farriery


Distinguishing between a foot with steep hoof angle and a true club foot is important. High hoof angles without phalangeal misalignment or with mild pha- langeal misalignment can generally be managed by adhering to good farriery guidelines for trimming such as using the hoof-pastern axis, the center of rotation, and trimming the heels of the hoof capsule to include the frog. It may be necessary with a high hoof angle or mild phalangeal alignment to gradu- ally trim the heels in a tapered fashion from the apex of the frog to the heels. This increases the ground surface of the foot and attempts to reestab- lish weight-bearing on the entire solar surface of the foot. Breakover is moved palmarly at the same time to compensate for any increased tension in the DDFT created by lowering the heels. This can be accomplished by rolling, rockering, or grinding breakover into the toe of the shoe. If improvement is noted, the horse should be trimmed/shod at 4 week intervals. Farriery to correct a high hoof angle accompanied


by a flexural deformity (club foot) becomes more of a challenge. Again, the object of farriery is to load the heels, compensate for the shortening of the DDFT, and improve the hoof-pastern axis. To ac- complish these objectives, farriery is directed at trimming the heels of the hoof capsule, but the amount of heel to remove can be difficult to deter- mine. In mild to moderate club feet, an estimate of how much heel to remove can be made by placing the thick end of a 2° or 3° pad under the toe of the foot and allowing the horse to stand on it10,19 (Fig. 9). If the horse does not resent the tension this places on the DDFT, this test allows the farrier to safely trim the hoof wall at the heels in a tapered fashion starting in a palmar direction from the widest part of the foot using the thickness of the degree pad as a guide. The toe is shortened by trimming the outer surface of the dorsal hoof wall with a rasp. The trimmed foot is fitted with a shoe that has the break- over forged or ground into it starting just dorsal to


Fig. 9. A wedge pad can be placed under the toe of a horse with a club foot, which will test the response when tension is exerted on the DDFT. The farrier can then determine the amount of hoof wall that can be safely removed from the heels of the hoof capsule.


the apex of the frog and tapering toward the toe to further decrease the stresses on the DDFT. There are also commercial shoes available that have a rockered toe that provide appropriate breakover. With the more advanced cases of club feet, the


heels should still be lowered to load the heels and unload the toe, but the addition of heel elevation following the trim is necessary to compensate for the shortening of the musculotendinous unit. The con- cept of lowering the heels with the trim then wedg- ing the palmar aspect of the hoof back up is often not understood. When the heels are trimmed back to the widest point of the frog, the load bearing surface area of the foot increases, and this is necessary for normal function of the hoof. However, the muscu- lotendinous unit must be accommodated and main- tained without excessive tension and pain. This is accomplished by decreasing the breakover and by adding elevation to the palmar aspect of the hoof. The degree of wedge that is applied often mimics the amount of heel removed, but in many cases may be less due to mechanical contributions made by rock- ering or rolling the toe of the shoe. The amount of heel elevation needed if necessary can be demon- strated following the trim by placing the trimmed foot on the ground 6 to 8 inches palmar to the con- tralateral limb. A space will generally appear be- tween the heels of the foot and the ground (Fig. 10). The author uses either a wedge shoe or places a degree pad or a bar wedge between the heels of the foot and the shoe to compensate for the shortening of the muscle-tendon unit (Fig. 11). This method al- lows the heels to be weight-bearing but at the same time decreases the stresses on the musculotendi- nous unit. Creating breakover in the shoe to fur- ther relieve stress in the DDFT, as described above, is essential. It is important to note that when the heels are elevated with a wedge shoe, the normal


AAEP PROCEEDINGS  Vol. 60  2014 69


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