Caudal lumbar vertebral fractures in California Quarter Horse and Thoroughbred racehorses.
Authors: Collar E M, Zavodovskaya R, Spriet M, Hitchens P L, Wisner T, Uzal F A, Stover S M
Journal: Equine veterinary journal
Summary
# Editorial Summary: Caudal Lumbar Vertebral Fractures in Racehorses Catastrophic lumbar vertebral fractures represent a significant welfare and safety concern in racing populations, yet their underlying pathophysiology remains poorly understood. Collar and colleagues examined post-mortem records spanning 22 years alongside detailed imaging and histological analysis of vertebral specimens from affected and control racehorses to characterise the anatomical and pathological features predisposing to these injuries. Quarter Horses showed a marked predilection for fractures at the L5–L6 junction (87% of cases), whilst Thoroughbreds displayed a more distributed pattern (48% at L5–L6), with lumbar vertebral fractures ranking as the third most common musculoskeletal cause of death in Quarter Horses and frequently occurring concurrent with jockey injury. All examined fracture specimens demonstrated oblique fracture lines traversing the cranioventral to caudodorsal plane across the L5–L6 vertebral endplates and intervertebral disc, coupled with pre-existing maladaptive pathology on the ventral aspect of the vertebral bodies—indicating that catastrophic failure occurs in already compromised tissue rather than representing acute trauma to normal bone. These findings emphasise the clinical importance of systematic lumbar assessment in racing populations, particularly at the L5–L6 region, as early detection of mild vertebral pathology may enable preventative intervention and reduce both equine fatalities and associated jockey injuries.
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Practical Takeaways
- •Routine radiographic assessment of the lumbar spine in racehorses, particularly Quarter Horses, may detect early vertebral pathology at L5-L6 and prevent catastrophic injuries
- •Pre-existing ventral vertebral body abnormalities should be recognized as a significant risk factor for lumbar fracture in racing animals, supporting early retirement decisions
- •Jockey safety protocols should include awareness that lumbar vertebral fractures are a notable cause of racehorse fatality and associated rider injury, particularly in Quarter Horse racing
Key Findings
- •Lumbar vertebral fractures occurred in 38 Quarter Horses and 29 Thoroughbreds over 22 years, with 87% of Quarter Horses and 48% of Thoroughbreds involving L5-L6 vertebrae
- •Lumbar vertebral fractures were the third most common musculoskeletal cause of death in Quarter Horses and frequently associated with jockey injuries
- •All 6 examined racehorse vertebral specimens with lumbar fractures showed pre-existing ventral vertebral body pathology that likely predisposed them to catastrophic fracture
- •Fractures coursed obliquely across adjacent L5-L6 vertebral endplates and intervertebral disc, with anatomical variations in vertebral number and processes present in affected horses