Characteristics of complete tibial fractures in California racehorses.
Authors: Samol Monika A, Uzal Francisco A, Hill Ashley E, Arthur Rick M, Stover Susan M
Journal: Equine veterinary journal
Summary
# Tibial Fractures in Racing Racehorses: A California Necropsy Study Complete tibial fractures account for approximately 3% of racehorse racing fatalities, yet their developmental pathways remain poorly characterised compared to other catastrophic musculoskeletal injuries. This 28-year retrospective necropsy analysis of 115 California racehorses examined fracture characteristics, signalment patterns, and exercise histories to establish whether pre-existing stress fractures predisposed horses to complete tibial fracture, as has been documented with other racing injuries. The majority of fractures (93%) were comminuted, occurred during training (68%) in 2–3-year-old horses (73%), and showed evidence of periosteal callus formation in 64% of examined cases—predominantly at the proximal diaphysis (65%)—indicating pre-existing stress injury. Affected horses demonstrated markedly different exercise patterns from matched controls, accumulating fewer official-timed works, races, active training days and total distance (P < 0.05); notably, 57% never raced and 36% had a layup period exceeding 60 days, suggesting inadequate or interrupted conditioning may have contributed to failure. For practitioners involved in racehorse management, these findings underscore the clinical significance of detecting early proximal diaphyseal stress fractures through imaging and monitoring training loads carefully in young horses, particularly during the critical 2–3-year-old period, as incomplete stress fracture management and irregular exercise patterns appear linked to catastrophic complete fracture.
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Practical Takeaways
- •Young racehorses (2-3 years) with tibial stress fractures that show reduced racing activity and limited official works are at high risk for catastrophic complete tibial fractures during training
- •The presence of periosteal callus on necropsy indicates these were largely stress fracture-related injuries; careful monitoring and appropriate rehabilitation protocols are critical in young horses showing signs of tibial stress
- •Layup periods in young racehorses warrant investigation for underlying stress fractures before return to training, as incomplete recovery may predispose to complete fracture
Key Findings
- •Tibial fractures occurred in 115 racehorses (97% unilateral), most commonly during training (68%) in 2- to 3-year-old horses (73%)
- •93% of fractures were comminuted, with 44% diaphyseal and 40% oblique; 64% of examined cases had periosteal callus indicating pre-existing stress fractures
- •Affected horses had significantly fewer official-timed works, races, active days, and accumulated less distance compared to matched controls (P < 0.05)
- •57% of affected horses with known exercise history never raced, and 36% had a layup period prior to fracture