Determining the validity and reliability of a novel hoof photography template in shod equines

Abstract

Background

Valid and reliable field tests may enable the equine health team to accurately assess and monitor hoof conformation. This study aimed to assess the validity of a newly-developed template to capture a true lateral photograph of the equine hoof, compared against a latero-medial view radiograph and an estimated true lateral photo.

Materials and methods

Two veterinarians took radiographs (RAD) of both forelimbs and measured the dorsal wall heel angle (DHWA) and heel angle (HA). Two Investigators captured photographs of each forelimb: one with the template (TEMP) and one estimated true lateral sans template (PHOTO). Concurrent validity was determined using intraclass correlation coefficients alongside Spearman’s rho. Agreement was assessed using non-parametric Bland Altman plots. Reliability and inter-observer reliability were calculated through intraclass correlation coefficients.

Results

Good concurrent validity was found for the DHWA across all methods (ICC= 0.85; p < 0.001, Spearman's r = 0.88, p < 0.01, whereas moderate agreement was observed for HA (ICC= 0.65; p < 0.001, Spearman’s r = 0.8, p < 0.01). Comparing methods, Bland-Altman plots revealed good agreement between RAD-TEMP, RAD-PHOTO (median difference= 0°; −0.4°, respectively) for DHWA. For HA, good agreement between RAD-TEMP and RAD-PHOTO was discovered (median difference= −1°; 0.5°, respectively). Further, widespread scatter was present on all plots. Reliability between RAD-TEMP and RAD-PHOTO for the DHWA was excellent (ICC= 0.92; p < 0.001, ICC= 0.90; p < 0.001, respectively). Moderate reliability was found between the RAD-TEMP (ICC= 0.63; p < 0.001) and RAD-PHOTO (ICC= 0.73; p < 0.001) for HA.

Conclusions

Mobile photography of the hoof shows promising validity and reliability when using the novel template and when taking an estimated true lateral photograph.