title: Caudal lumbar vertebral fractures in California Quarter Horse and Thoroughbred racehorses.
abstract: BACKGROUND
  To gain insight into the pathophysiology of equine lumbar vertebral fractures in racehorses.
  
  
  OBJECTIVE
  To characterise equine lumbar vertebral fractures in California racehorses.
  
  
  METHODS
  Retrospective case series and prospective case-control study.
  
  
  METHODS
  Racehorse post mortem reports and jockey injury reports were retrospectively reviewed. Vertebral specimens from 6 racehorses affected with lumbar vertebral fractures and 4 control racehorses subjected to euthanasia for nonspinal fracture were assessed using visual, radiographic, computed tomography and histological examinations.
  
  
  RESULTS
  Lumbar vertebral fractures occurred in 38 Quarter Horse and 29 Thoroughbred racehorses over a 22 year period, primarily involving the 5th and/or 6th lumbar vertebrae (L5-L6; 87% of Quarter Horses and 48% of Thoroughbreds). Lumbar vertebral fractures were the third most common musculoskeletal cause of death in Quarter Horses and frequently involved a jockey injury. Lumbar vertebral specimens contained anatomical variations in the number of vertebrae, dorsal spinous processes and intertransverse articulations. Lumbar vertebral fractures examined in 6 racehorse specimens (5 Quarter Horses and one Thoroughbred) coursed obliquely in a cranioventral to caudodorsal direction across the adjacent L5-L6 vertebral endplates and intervertebral disc, although one case involved only one endplate. All cases had evidence of abnormalities on the ventral aspect of the vertebral bodies consistent with pre-existing, maladaptive pathology.
  
  
  CONCLUSIONS
  Lumbar vertebral fractures occur in racehorses with pre-existing pathology at the L5-L6 vertebral junction that is likely predisposes horses to catastrophic fracture. Knowledge of these findings should encourage assessment of the lumbar vertebrae, therefore increasing detection of mild vertebral injuries and preventing catastrophic racehorse and associated jockey injuries.
authors.affiliation: J.D. Wheat Veterinary Orthopedic Research Laboratory, School of Veterinary Medicine, University of California, Davis, USA.|Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, USA.
authors.forename: E M
authors.identifier: http://orcid.org/0000-0003-2734-8675
authors.initials: EM
authors.lastname: Collar
authors.affiliation: J.D. Wheat Veterinary Orthopedic Research Laboratory, School of Veterinary Medicine, University of California, Davis, USA.|Comparative Pathology Graduate Group, School of Veterinary Medicine, University of California, Davis, USA.
authors.forename: R
authors.initials: R
authors.lastname: Zavodovskaya
authors.affiliation: Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, USA.
authors.forename: M
authors.initials: M
authors.lastname: Spriet
authors.affiliation: J.D. Wheat Veterinary Orthopedic Research Laboratory, School of Veterinary Medicine, University of California, Davis, USA.|One Health Institute, School of Veterinary Medicine, University of California, Davis, USA.
authors.forename: P L
authors.initials: PL
authors.lastname: Hitchens
authors.affiliation: J.D. Wheat Veterinary Orthopedic Research Laboratory, School of Veterinary Medicine, University of California, Davis, USA.
authors.forename: T
authors.initials: T
authors.lastname: Wisner
authors.affiliation: California Animal Health and Food Safety Laboratory, School of Veterinary Medicine, University of California - Davis, San Bernardino, USA.
authors.forename: F A
authors.initials: FA
authors.lastname: Uzal
authors.affiliation: J.D. Wheat Veterinary Orthopedic Research Laboratory, School of Veterinary Medicine, University of California, Davis, USA.|Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California, Davis, USA.
authors.forename: S M
authors.initials: SM
authors.lastname: Stover
mesh_terms: D000818:Animals; D001265:Athletic Injuries; D002140:California / Q000453:epidemiology; D016022:Case-Control Studies; D005260:Female; D050723:Fractures, Bone / Q000453:epidemiology / Q000401:mortality / Q000473:pathology / Q000662:veterinary*; D006734:Horse Diseases / Q000453:epidemiology / Q000401:mortality / Q000473:pathology*; D006736:Horses; D006801:Humans; D008159:Lumbar Vertebrae / Q000473:pathology*; D008161:Lumbosacral Region; D008297:Male; D012189:Retrospective Studies; D012420:Running; D013122:Spinal Diseases / Q000453:epidemiology / Q000473:pathology / Q000662:veterinary; D013177:Sports
keywords: fracture; horse; lumbar; racehorse; spine; spondylosis; vertebra