Modifying the Surface of Horseshoes: Effects of Eggbar, Heartbar, Open Toe, and Wide Toe Shoes on the Phalangeal Alignment, Pressure Distribution, and the Footing Pattern

• Surface modifications of the shoes show their main effect on penetrable ground.
• Bar shoes cause an increased palmar angle (PA) on penetrable ground.
• No consistent data assessable for the alignment of PI/PII regarding to a changed PA.
• Pressure peaks occurred underneath the supported region of the hoof capsule.
• Modifications altering the surface show no distinct influence on the footing pattern.

This study assesses the biomechanical effects on the phalangeal alignment, the pressure force distribution, and the footing pattern on different grounds created by different horseshoes modified in the dorsopalmar surface. Twenty-five warmblood horses were divided into five groups (n = 5). In each group, radiographic and kinetic examinations were carried out for each barefoot hoof, standard, and modified horseshoe. For radiographic measurements, a modified podoblock, simulating firm and penetrable ground, was used. For kinetic examinations, hoof and horseshoe were simultaneously equipped with sensor foils and horses were walked on different grounds (concrete, rubber, firm, and deep sand). None of the horseshoes showed an effect on the bone alignment on firm ground. On penetrable ground, the bar shoes caused a steeper palmar angle (P3), whereas with a wide toe shoe, a flatter orientation of the distal phalanx was observable. The influence on the alignment of the middle and proximal phalanx showed no constant data. On penetrable ground, pressure peaks occurred at the heels after the application of bar shoes. Moreover, pressure peaks were observable beneath the ends of the branches of the open toe shoe, and the toe and thin branches of the wide toe shoe. The footing pattern was only affected by the open toe shoe. In conclusion, the biomechanical effects of the examined modified horseshoes are mainly influenced by different ground conditions. Moreover, unintended side effects such as unexpected pressure peaks or an enhanced mediolateral sink in of the hoof occur in addition to the required impacts during a therapeutical treatment.