Diagnostic accuracy of digital photography and image analysis for the measurement of foot conformation in the horse.
BACKGROUND
Rigorous evaluation of practicable methods for the objective assessment of foot conformation has not been performed.


OBJECTIVE
To assess the practicability, precision and accuracy of the process of obtaining measurements of horses' feet using photography and image processing software.


METHODS
Precision study: Lateral photographs of horses' feet were obtained twice by 2 veterinary surgeons (image acquisition - IAc). Photographs were analysed by 2 masked veterinary surgeons on 2 occasions (image analysis - IAn). Measurements were compared within and between operators for self and non-self acquired photographs. Agreement indices (AIs) and 95% limits of agreement (LOA) were calculated for the IAn process alone and for the combined IAc + IAn processes. Accuracy study: Measurements obtained from lateral photographs were compared with those obtained from lateromedial radiographs. AIs and 95% LOA were calculated for each measurement.


RESULTS
Precision study: Mean intra- and interoperator AIs for the IAn process alone were > or = 0.90 while those for the combined IAc + IAn processes were > or = 0.89 for all measurements. Similar mean AIs and 95% LOA were calculated regardless of image origin. The 95% LOA for hoof angle, heel height/toe height% and coronary band angle for all comparisons were within target values. Accuracy study: Mean AIs were > or = 0.89 for all measurements. The 95% LOA for heel height/toe height% and coronary band angle were within target values.


CONCLUSIONS
Excellent precision was identified within and between operators regardless of image origin. High levels of accuracy were also identified, especially for heel height/toe height% and coronary band angle, indicating that photography and radiography may be used interchangeably.


CONCLUSIONS
Acquisition and analysis of photographic images is an appropriate method for the objective measurement of foot conformation, both in clinical and, research settings.
White
J M
JM
Weipers Centre Equine for Equine Welfare, Division of Companion Animal Sciences, Faculty of Veterinary Medicine, University of Glasgow, Glasgow G61 1QH, UK.
Mellor
D J
DJ
Duz
M
M
Lischer
C J
CJ
Voute
L C
LC
D000818:Animals; D001696:Biomechanical Phenomena; D005260:Female; D005534:Foot Diseases / Q000175:diagnosis / Q000662:veterinary*; D006724:Hoof and Claw / Q000033:anatomy & histology* / Q000502:physiology*; D006734:Horse Diseases / Q000175:diagnosis*; D006736:Horses / Q000502:physiology*; D006801:Humans; D008297:Male; D015588:Observer Variation; D010781:Photography / Q000379:methods / Q000592:standards / Q000662:veterinary*; D011897:Random Allocation; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012984:Software