Is each horse unique and unrepeatable? An explanation through morphometric and statistical analysis of the limb bones

Horses went through functional differentiation during their evolutionary and reproductive development, however, some body parts continued to improve their specificity for speed. Regarding this, we evaluated by morphometric analysis the relationship between limb section (LS) differences in the appendicular structures of horses. Two hundred and seven (n = 207) adult horses of different breeds and sex were selected. The limb section was measured by identification of topographic palpable skeleton landmarks with a measurement tape (centimetres). Quantitative variables (limb section) were analysed with PAST Paleontological Statistics Version 3.16. Spearman's ordinal or non-parametric correlation coefficient was used to study the relationship between the limb section of each variable (p < 0.05), with a low coefficient of variation (<30%). In 45 analysed correlations, 35 were statistically significant and 10 were discarded because p > 0.05. These results show that most variables were correlated with each other. As a result, we can imply that some LS of the horse's limbs are correlated with each other, positively or negatively and to a different degree. In conclusion, the correlations between LS lengths determine the size and shape of each horse, making individual horses unique and unrepeatable.