Hoof morphometry in a population of lame and nonlame working donkeys in Pakistan

Background: Hoof morphometry, conformation and shoeing practices have all been associated with lameness in horses. Hoof morphometry in working donkeys in Pakistan has not been objectively measured. 
Objectives: To quantitatively assess hoof morphology in donkeys, to identify factors underlying hoof morphology, and interrelationships between conformation, lameness, and shoeing status. 
Study design: Cross-sectional study. 
Methods: Donkeys were assessed in-harness using a modified five-point lameness scale by two veterinarians and digital photographs of front hooves taken alongside a grid. Factor analysis was used to examine the interrelationships among morphometric data. Associations between conformation, shoeing, age and lameness were assessed. 
Results: Sixty-one donkeys were examined; 28 were unshod. There were significant left–right hoof asymmetries between heel height (0.27, SD 0.92 cm; p = 0.02), toe-heel angle (2.97°, SD 8.85°; p = 0.03) and medio-lateral symmetry (0.5, SD 1.75 cm; p = 0.05). Ten percent of donkeys (n = 6) were sound and 64% donkeys (n = 39) were consistently lame. Conformational defects were seen in 41% (n = 25) of donkeys. Eleven factors were extracted, accounting for 83% of the variance encountered in the original variables. Shoeing, and asymmetry between or within feet were not associated with lameness in donkeys; older donkeys were more likely to be lame (p = 0.02). 
Main limitations: As a convenience sample of draught donkeys, most of which were lame, the study may not reflect nonpathological hoof morphology in working donkeys. There are no validated objective lameness measures for donkeys and donkeys were in harness when assessed. 
Conclusion: This study represents a snapshot of hoof morphology and lameness in a single population and under various limitations. Further work should use larger datasets and more homogenous samples to discriminate between ‘normal’ and ‘abnormal’ feet and how these might contribute to lameness. Factor analysis highlighted the clustering of hoof morphometric features in donkeys, suggesting the potential for targeted studies in the future. © 2022 The Authors. Equine Veterinary Journal published by John Wiley & Sons Ltd on behalf of EVJ Ltd.