Factors influencing the occurrence of hoof thrush in horses

The horse's hoof is a crucial element that affects the individual's health and its further use. This study aimed to assess the degree of dependence between the occurrence of thrush and the horse's size, and age, and to evaluate the impact of hoof shape and trimming on the occurrence of thrush. A total of 44 horses were included in the study, and 176 hooves were evaluated. A methodology for assessing the occurrence of thrush in horse hooves based on its intensity on a scale ranging from 0 to 5 was developed. For objective evaluation of hoof shape, the Frog Width Index (IFW) was created, which correlates the width of the frog and the circumference of the hoof: Frog Width Index = (frog width ÷ hoof circumference) × 100. Based on this index, the risk of thrush occurrence in the hooves was evaluated. In narrow hooves with IFW = 10, an extremely high incidence of thrush can be expected, with an average of 2.5 in this study. Hooves with IFW ≥ 14 had an average thrush grade of less than 1. A positive correlation was statistically confirmed between the occurrence of thrush and chest circumference, withers height, estimated weight, and age. The dependency of thrush grade on IFW was fitted with a polynomial trend line with the equation thrush grade = 0.02 IFW2 - 0.89 IFW + 9.15, R2 = 0.98. This is a decreasing function, where a sharp increase in the risk of thrush was observed when the IFW value dropped below 14. A higher average thrush grade was demonstrated (P < 0.05) in shod hooves (1.34) compared to trimmed hooves (0.67). Based on this study, any horse owner can evaluate the shape of their horse's hoof using IFW and determine the risk level of thrush occurrence.