Locomotor characteristics of horses with navicular disease

Objective-To determine whether force-plate evaluation of horses with navicu lar disease would reveal an abnormal gait that persists despite loss of sen sation to the palmar foot region, which may predispose such horses to navic ular disease. Animals-17 clinically normal Thoroughbreds and 8 Thoroughbreds with navicul ar disease. Procedure-Data on ground reaction forces were obtained in trotting horses, using a force plate. Force-time curve variables for clinically normal horse s were derived from 4 points at the beginning and 4 points at the end of th e vertical and craniocaudal horizontal plots. Principal component analysis was undertaken separately on beginning-of-stride and end-of-stride data, an d the first 2 components were represented graphically. Rotation matrices we re applied to equivalent data for horses with navicular disease before and after disruption of sensation by administration of a palmar digital nerve b lockade. Results-Prior to nerve block, horses with navicular disease differed signif icantly from normal horses for beginning-of-stance phase and end-of-stance phase variables. After nerve block, horses with navicular disease maintaine d the same significant differences from clinically normal horses only for v ariables at the beginning-of-stance phase. Conclusions and Clinical Relevance-Horses with navicular disease have abnor mal limb-loading force patterns that are not altered by loss of sensation i n the palmar region. These abnormal patterns were detected in a horse witho ut navicular disease. Some horses are predisposed to navicular disease as a result of an inherent abnormal gait pattern. Analysis of gait patterns cou ld be used for detection and appropriate management of horses susceptible t o development of navicular disease.