The effect of foot imbalance on point of force application in the horse.

This research investigates the effects of foot imbalance in horses, by using wedges attached to shoes to alter horse foot balance, and evaluating how it changes force application points, using thoroughbreds as the sample group. The results indicate that horses cannot compensate for an abrupt foot imbalance, which may further lead to detrimental effects on the hoof structure and horn growth.

Methodology of the Study

• The study used thoroughbred horses as subjects. Their front feet were modified using wedges attached to their shoes, to purposely create an imbalance on either left or right. The wedges used had angles of 3.7 and 5 degrees.
• The research aimed to measure the point of force application during weight-bearing and evaluated how it altered when trotting. This observation was made using a force plate system, a device used to measure the ground reaction forces during walking and running.
• A minimum of 4 horses were recruited to provide data for each experimental condition while a total of 8 horses were studied overall.

Research Findings

• The results of this study showed that, when a standard steel horse shoe is applied to a balanced foot, it has minimal effect on the force trace – that means the sequence of force applied over time – throughout stance, implying the horse’s ability to withstand minor perturbations in balance without significant shifts in force distribution.
• However, when the balance of the hoof was intentionally altered, the point of force application shifted by approximately 10 mm, in the direction of the wedge. This suggests that an acute imbalance in the horse’s foot may significantly affect how force is distributed during weight-bearing activities.
• The study also found that the heel’s elevation delayed the unloading of the heel – the process of removing pressure from the heel during locomotion – and increased the application of force to that region. Conversely, raising the toe led to the advancement of unloading, thus reducing the force applied to the toe.
• The researchers reassessed the horses 24 hours after shoeing and found minimal changes in the force trace. This suggests that the horse’s inability to compensate or redistribute the load under its foot following an acute imbalance was ongoing, and that the altered force distribution was not just a transient effect.
• This conclusion leads to the concern that higher loads in the elevated region could have a destructive effect on the hoof structure and horn growth of the horse.

Conclusions and Implications

• The findings demonstrate that an acute foot imbalance can lead to significant shifts in force distribution during locomotion in horses. The inability of the horse to re-distribute the load underfoot may lead to increased wear and potential injury in the area taking the additional load.
• The insights from this research underscore the importance of proper hoof balance and shoeing in maintaining the health and performance of horses. It also throws light on the possible detrimental effects of incorrect shoeing techniques which could lead to foot imbalance and a number of related problems.