Hoof size, shape, and balance as possible risk factors for catastrophic musculoskeletal injury of Thoroughbred racehorses

Objective-To evaluate hoof size, shape, and balance as risk factors for cat astrophic musculoskeletal injuries (CMI), including suspensory apparatus fa ilure (SAF) and cannon bone condylar fracture (CDY) in Thoroughbred racehor ses. Animals-95 Thoroughbred racehorses that died between 1994 and 1996. Procedure-38 quantitative measures of hoof size, shape, and balance were ob tained from orthogonal digital images of the hoof and were compared between case horses with forelimb CMI (70), SAF (43), and CDY (10) injuries and co ntrol horses whose death was unrelated to the musculoskeletal system (non-C MI, 25). Comparison of group means between cases and controls was done usin g ANOVA, and multivariable logistic regression was used to estimate odds ra tios. Results-Odds of CMI were 0.62 times lower for a 5-mm increase in ground sur face width difference and 0.49 times lower for a 100-mm(2) increase in sole area difference. Odds of SAF were 6.75 times greater with a 10 degrees inc rease in toe-heel angle difference and 0.58 times lower with a 100-mm2 incr ease in sole area difference. Odds of CDY were 0.26 times lower with a 3 de grees increase in toe angle, 0.15 times lower with a 5-mm increase in later al ground surface width, and 0.35 times lower with a 100-mm(2) increase in sale area difference. Clinical Relevance-decreasing the difference between toe and heel angles sh ould decrease risk of SAF for Thoroughbred racehorses and should be conside red in addition to increasing toe angle alone to help prevent catastrophic injury. Trimming the hoof to perfect mediolateral symmetry may not be a sou nd approach to avoiding injury.