Changes in pressure distribution of the solar surface after a single trimming event are associated with external hoof measurements in the equine fore foot.

Background: Trimming is critical for a functioning equine hoof. Pressure distribution provides information on loading; however, information on the effects of trimming on pressure distribution is lacking.

Objectives: To describe the pressure changes of equine fore feet following trimming.

Study Design: Cross-sectional cohort study.

Methods: Fifty sound horses were recruited. Eighteen external hoof measures of the dorsal, lateral, medial and solar aspects were obtained before and after trimming from 94 fore feet. Horses were walked over a pressure mat before and after trimming and pressure maps of the solar surface created. Percentage change in hoof measures were assessed. Factors associated with an increase in pressure in the frog region after trimming were entered into a forward likelihood ratio logistic regression model. Odd ratios (ORs) with 95% confidence intervals (CI) and area under the curve receiver operator characteristics (AUROC) were calculated. Sensitivity and specificity were calculated at a cut-off value of p = 0.5.

Results: Trimming resulted in a significant increase in pressure, topographically mapped to the frog region, in 12/94 (13% 95% CI 6; 20) feet. Percentage difference in bearing border length (OR 0.66 95% CI 0.51; 0.86), heel buttress to centre of pressure distance (OR 1.30 95% CI 1.10; 1.53), heel angle (lateral side) (OR 1.11 95% CI 1.04; 1.19) and heel length (medial side) (OR 0.92 95% CI 0.85; 0.99) were retained in the final model associated with increased pressure in the frog region following trimming. AUROC was excellent (0.94 95% CI 0.88; 0.99) with fair sensitivity (58% [95% CI 50; 66]) and excellent specificity (98% [95% CI 78; 118]).

Main Limitations: Subjective lameness exam; horse velocity unmeasured.

Conclusions: Measuring pressure changes over the solar surface of the equine fore foot after trimming identified that an increased pressure in the frog region was linked to specific changes in hoof shape.