Locomotor characteristics of horses with navicular disease

OBJECTIVE: To determine whether force-plate evaluation of horses with navicular disease would reveal an abnormal gait that persists despite loss of sensation to the palmar foot region, which may predispose such horses to navicular disease. ANIMALS: 17 clinically normal Thoroughbreds and 8 Thoroughbreds with navicular disease. PROCEDURE: Data on ground reaction forces were obtained in trotting horses, using a force plate. Force-time curve variables for clinically normal horses were derived from 4 points at the beginning and 4 points at the end of the vertical and craniocaudal horizontal plots. Principal component analysis was undertaken separately on beginning-of-stride and end-of-stride data, and the first 2 components were represented graphically. Rotation matrices were applied to equivalent data for horses with navicular disease before and after disruption of sensation by administration of a palmar digital nerve blockade. RESULTS: Prior to nerve block, horses with navicular disease differed significantly from normal horses for beginning-of-stance phase and end-of-stance phase variables. After nerve block, horses with navicular disease maintained the same significant differences from clinically normal horses only for variables at the beginning-of-stance phase. CONCLUSIONS AND CLINICAL RELEVANCE: Horses with navicular disease have abnormal limb-loading force patterns that are not altered by loss of sensation in the palmar region. These abnormal patterns were detected in a horse without navicular disease. Some horses are predisposed to navicular disease as a result of an inherent abnormal gait pattern. Analysis of gait patterns could be used for detection and appropriate management of horses susceptible to development of navicular disease.