Evaluation of a plastic shoe

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Hoof-related lameness in horses is common; however, very few critical studies have been performed to evaluate the ability of different shoes to reduce lameness. Dr. Chris Kawcak, with Drs. David Frisbie and Wayne McIlwraith, worked with Val Perino, an MS student, to develop a project intended to compare horses that were unshod, shod with steel shoes, and shod with plastic shoes (Dynamix shoes) in both balanced and controlled, unbalanced states. The specific aims of the study were to compare clinical lameness, ground reaction force, and hoof strain in unshod, traditionally shod, and Dynamix shod horses in both balanced and controlled, unbalanced states. This led to the hypothesis that Dynamix shod horses would have less clinical lameness, increased ground reaction force, and less hoof strain than unshod and traditionally shod horses. Six horses, ages 3 to 5 years, were chosen for the study and treated in accordance with ACUC protocol. The first groups of measurements were on hooves that were trimmed for normal balance. The left front hooves of all horses were then trimmed in an unbalanced manner starting on week 18. Lameness was graded in each horse at a jog according to a subjective lameness scoring system. Each horse was also jogged across a Tekscan sensor mat at a controlled speed. The force, pressure, and contact area were determined for each hoof. Rosette strain gauges were also applied to the prepared hoof at the medial and lateral quarters in both parallel and perpendicular fashion. Data were analyzed by using a mixed model analysis of variance and least squares mean when appropriate. A P value less than .05 was considered significant. Horses were significantly more lame when they wore Dynamix shoes without the clips compared with clips. The controlled, unbalanced model induced a level of lameness that was appropriate for seeing the effects of treatment. It was also found that the horses were less lame in Dynamix shoes compared with when they were unshod in both balanced and unbalanced states. Ground reaction force was highest in the Dynamix treatment group compared with the traditionally shod group. However, the force was higher in the unshod and Dynamix treatment groups when the hooves were unbalanced, which does not correlate with the increased lameness seen when the hooves were unbalanced. The controlled, unbalanced treatment significantly reduced lateral coronary band compression as seen by a reduction in lateral transverse hoof strain. In conclusion, the Dynamix shoe appears to reduce lameness in both balanced and unbalanced states; however, the clips appear to be an essential component of the design. This is the first time that the Tekscan technology has been used to assess abnormal hoof conformation and the investigators are currently planning to further evaluate the Tekscan system against a force plate to determine the meaning of these data. (From Colorado State University Orthopaedic Researach Center Laboratory Report. The complete study was published as: Perino, V MS Thesis. Colorado State University. 2002.) Copyright 2002, Elsevier Science (USA). All rights reserved. 0737-0806/02/2208-0008$35.00/0 doi:10.1053/jevs.2002.37110 Fig 1. (A) Natural Balance shoe, (B) Egg Bar shoe, and (C) Dynamix shoe.