title: Prevalence, location and symmetry of noncatastrophic ligamentous suspensory apparatus lesions in California Thoroughbred racehorses, and association of these lesions with catastrophic injuries.
abstract: BACKGROUND
  Knowledge of the site distribution of ligamentous injuries facilitates clinical diagnosis of suspensory apparatus conditions.
  
  
  OBJECTIVE
  To determine if lesions within the suspensory ligament (SL) and distal ligaments of the proximal sesamoid bones (DSLs) were associated with suspensory apparatus failure or metacarpal lateral condylar fracture in California Thoroughbred racehorses.
  
  
  METHODS
  Cross-sectional study.
  
  
  METHODS
  Suspensory apparatus specimens from 327 deceased Thoroughbred racehorses were sectioned within the SL body and branches, and oblique and straight DSLs. Purple lesions ≥2 mm in width were categorised as moderate and paler or smaller lesions as mild. Associations between moderate lesions and age, sex, racetrack and cause of death were evaluated using multivariable logistic regression.
  
  
  RESULTS
  Moderate lesions were evident in 16% and milder lesions in 77% of racehorses. Moderate lesions occurred with similar frequency in SL branches and oblique DSLs. Moderate lesions were more likely to occur in horses that died as a result of suspensory apparatus failure (odds ratio [OR] = 4.60; 95% confidence interval [CI] 1.61-13.13; and P = 0.004) or metacarpal lateral condylar fracture (OR = 5.05; 95% CI 1.42-17.93; and P = 0.012) compared with horses that died from nonmusculoskeletal causes, and in horses aged ≥7 years horses compared with 2-year-old horses (OR = 5.33; 95% CI 1.44-19.75; and P = 0.012).
  
  
  CONCLUSIONS
  Moderate lesions are common in the SL branches and oblique DSLs of racehorses, and may be associated with risk for suspensory apparatus failure and metacarpal condylar fracture. Monitoring health of the suspensory apparatus ligamentous structures may be a simple means of assessing fatigue in, and preventing more extensive injuries to, the forelimb suspensory apparatus and metacarpal condyles.
authors.affiliation: California Animal Health and Food Safety Laboratory System, University of California, Davis, USA.
authors.forename: A E
authors.identifier: http://orcid.org/0000-0002-9546-5630
authors.initials: AE
authors.lastname: Hill
authors.affiliation: Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, Canada.
authors.forename: I A
authors.initials: IA
authors.lastname: Gardner
authors.affiliation: EpiCentre, Massey University, Palmerston North, New Zealand.
authors.forename: T E
authors.initials: TE
authors.lastname: Carpenter
authors.affiliation: J. D. Wheat Veterinary Orthopedic Research Laboratory, Department of Anatomy, Physiology, and Cell Biology, University of California, Davis, USA.
authors.forename: C M
authors.initials: CM
authors.lastname: Lee
authors.affiliation: J. D. Wheat Veterinary Orthopedic Research Laboratory, Department of Anatomy, Physiology, and Cell Biology, University of California, Davis, USA.
authors.forename: P L
authors.initials: PL
authors.lastname: Hitchens
authors.affiliation: J. D. Wheat Veterinary Orthopedic Research Laboratory, Department of Anatomy, Physiology, and Cell Biology, University of California, Davis, USA.
authors.forename: S M
authors.initials: SM
authors.lastname: Stover
mesh_terms: D000818:Animals; D002140:California; D002423:Cause of Death; D005260:Female; D005552:Forelimb / Q000293:injuries* / Q000473:pathology; D006734:Horse Diseases / Q000209:etiology / Q000473:pathology*; D006736:Horses / Q000293:injuries*; D008022:Ligaments / Q000293:injuries*; D008297:Male; D012420:Running; D012716:Sesamoid Bones; D013177:Sports
keywords: horse; ligament injury; risk factors; suspensory apparatus