Preliminary Investigations Into Photogrammetric Measurement of Hoof Shape

An investigation into different measurement techniques to assess equine proximal hoof circumference

Equine hoof conformation is integral to equine performance and soundness. Consequently, it is a major area of interest within the field of equine health. Researchers have measured several hoof shape parameters to study the hoof conformation. Proximal hoof circumference (PHC) is a primary hoof shape parameter, and its assessment may help to recognize the early stages of the development of changes in hoof morphology or poor hoof shape. Previous studies have mainly used a measuring tape to measure PHC. However, some doubts still exist regarding the reliability, repeatability and accuracy of measuring tape in this context. The current study conducted a technical comparison between the measuring tape and two alternative methods of 3D scanning and photogrammetry to measure PHC. Five equine limbs were collected from five adult horses, and the PHC of the limbs was measured using these three methods. The 3D scanner method was considered to be the highest accuracy and the reference for method comparisons. Pairwise correlations between the 3D scanner and the other two methods were conducted using a linear mixed model. The measuring tape and photogrammetry tended to overestimate the mean PHC compared to the 3D scanner by 0.96 mm (P > 0.05) and 2.2 mm (P < 0.05), respectively. In addition, an excellent interrater and intrarater correlation coefficient (ICC) index was reported for the reliability of the tape measurements. The variation of the tape measurements was +/-2 mm, which justified the use of measuring tape for PHC measurements in various clinical and horse management applications.