title: Short- and long-term racing performance of Standardbred pacers and trotters after early surgical intervention for tarsal osteochondrosis.
abstract: BACKGROUND
  Osteochondrosis (OC) is commonly diagnosed in young Standardbred racehorses but its effect on performance when surgically treated at a young age is still incompletely understood. This is especially true for Standardbred pacers, which are underrepresented in the existing literature.
  
  
  OBJECTIVE
  To characterise the short- (2-year-old) and long-term (through 5-year-old) racing performance in Standardbred pacers and trotters after early surgical intervention (<17 months of age) for tarsal OC.
  
  
  METHODS
  Retrospective clinical study.
  
  
  METHODS
  The study population consisted of related, age-matched Standardbred racehorses (n = 278; 151 pacers, 127 trotters) with (n = 133) or without (n = 145) one or more tarsal OC lesions. All OC-affected horses were treated surgically prior to being sold as yearlings. Data obtained from publicly available race records for each horse included starts, wins, finishes in the top 3 (win, place or show), earnings and fastest time. Comparisons between OC-affected and unaffected horses were made for the entire population and within gaits. A smaller related population (n = 94) had these performance measures evaluated for their 2-5-year-old racing seasons.
  
  
  RESULTS
  Osteochondrosis status was associated with few performance measures. Trotters were at higher risk for lesions of the medial malleolus but lower risk for lesions of the distal intermediate ridge of the tibia than were pacers. Horses with bilateral OC lesions and lateral trochlear ridge (LTR) lesions started fewer races at 2 years of age than those with unilateral lesions or without LTR lesions.
  
  
  CONCLUSIONS
  Osteochondrosis seemed to have minimal effect on racing performance in this cohort, although horses with bilateral and LTR lesions started fewer races at 2 years. There was evidence for different distribution of OC lesions among pacers and trotters, which should be explored further. Standardbreds undergoing early removal of tarsal OC lesions can be expected to perform equivalently to their unaffected counterparts.
authors.affiliation: Veterinary Population Medicine Department, University of Minnesota, St. Paul, USA.
authors.forename: A M
authors.initials: AM
authors.lastname: McCoy
authors.affiliation: Department of Animal Science, Rutgers, The State University of New Jersey, New Brunswick, USA.
authors.forename: S L
authors.initials: SL
authors.lastname: Ralston
authors.affiliation: Veterinary Population Medicine Department, University of Minnesota, St. Paul, USA.
authors.forename: M E
authors.initials: ME
authors.lastname: McCue
mesh_terms: D000375:Aging; D000818:Animals; D005260:Female; D006734:Horse Diseases / Q000601:surgery*; D006736:Horses; D008297:Male; D055034:Osteochondrosis / Q000601:surgery / Q000662:veterinary*; D012189:Retrospective Studies; D013177:Sports; D013643:Tarsus, Animal / Q000601:surgery*
keywords: Standardbred; arthroscopy; horse; osteochondrosis; performance; racing