Subjective analysis of exercise-induced changes in back dimensions of the horse: The influence of saddle-fit, rider skill and work quality.

Recommendations concerning saddle-fit are empirical rather than based on scientific information. A saddle needs to fit the horse in motion, but there has been no investigation of whether the thoracolumbar region changes in dimensions in association with exercise. The objectives of this study were to quantify exercise-induced back dimension changes and to describe the association with work quality, saddle-fit and rider skill. Sixty-three sports horses in regular work were assessed prospectively in a non-random, cross-sectional survey. Thoracolumbar dimensions/symmetries were measured at predetermined sites before and immediately after a 30 min exercise period; widths for two levels at each site were measured and the shape-ratio calculated. The work quality and rider skill were graded and the presence of lameness and saddle-fit were recorded. Descriptive statistics, univariable and multivariable mixed-effect linear regression were performed to assess the relationship between horse-saddle-rider factors and changes in back dimensions. The mean back width after ridden exercise was greater compared with before exercise. Mean changes were greater in horses working correctly vs. those not working correctly, in those with correctly-fitting vs. ill-fitting saddles, and in horses ridden by good > moderately > poorly skilled riders. Back-width changes were significantly associated with saddle-fit. The back dimensions of horses working correctly change transiently with work. If a saddle does not fit properly before exercise, this increase in size does not occur. Saddle-fit should be assessed both before and after exercise to ensure correct fit.