Effect of shoeing conditions on hoof dimensions in Icelandic and Warmblood horses

In Icelandic horses (ICE), high, long hooves with added weights are often used to improve gait quality in competitions. From a biomechanical point of view, excessively long hooves can be problematic as they increase forces acting on the distal limb. The study aimed to determine if hoof capsule size and angle of ICE at competitions are comparable to those of Warmblood horses (WB) requiring shoeing. Hoof dimensions and balance were quantified in 13 horses of each breed at the beginning of a shoeing period (BSP), allowing a baseline comparison between breeds, as well as for WB at the end of a shoeing period (ESP) and for ICE when shod for competition (COMP). Left front and hind hoof capsules and bony structures of the hooves were measured on lateromedial and dorsopalmar/dorsoplantar radiographs at BSP (ICE, WB), ESP (WB) and COMP (ICE), respectively, using the software Metron-Hoof-Pro. Compared to WBBSP, ICEBSP had larger hoof capsules relative to the size of P3 and, when controlled for withers height, longer dorsal hoof wall lengths. The comparison of ICECOMP to WBESP indicated that the relative increase in hoof length and volume was greater in ICECOMP compared to WBESP. Hoof balance was closer to previously published values in WBs, while hoof angles in ICE (particularly palmar/plantar angle of P3) were generally larger and thus less problematic. In conclusion, hooves of ICECOMP were relatively larger and less balanced than WBESP, but hoof angles in WB were smaller than in ICE.