title: Associations between yearling exercise and interruptions during race training in Thoroughbred racehorses.
abstract: OBJECTIVE
  To investigate the effect of exercise during yearling sales preparation on the risk of interruptions during training in Thoroughbred racehorses.
  
  
  METHODS
  114 Thoroughbred racehorses.
  
  
  METHODS
  Information regarding the daily exercise of yearlings during sales preparation was obtained prospectively from a convenience sample of stud farms. Yearlings were followed to entry into race training, and subsequently, daily training information was recorded until the end of the racing season. Competing-risks survival analysis was used to model time from entry into race training to voluntary training interruption (no known condition or disease identified) and time from entry into race training to involuntary training interruption (due to presence of a condition or disease) occurring before the first trial (practice race for education). Total hand walking time and mechanical walker time accumulated during sales preparation were the main exposures of interest.
  
  
  RESULTS
  82 of 114 (71.9%) horses had an interruption before the first trial; 65 (79%) interruptions were voluntary, and 17 (21%) interruptions were involuntary. Increased total hand walking time was significantly associated with decreased risk of voluntary interruptions, whereas longer cumulative distances at a canter were significantly associated with decreased risk of involuntary interruptions.
  
  
  CONCLUSIONS
  Results identified an association between early exercise during sales preparation and decreased risk of voluntary interruption and increased risk of involuntary interruption during training of 2-year-old Thoroughbred racehorses. Further investigation into the effects of early exercise on racing performance is needed, but results have indicated that there may be an opportunity to modify early exercise programs.
authors.affiliation: Institute of Veterinary, Animal and Biomedical Sciences, College of Sciences, Massey University, Palmerston North 4474, New Zealand. c.bolwell@massey.ac.nz
authors.forename: Charlotte F
authors.initials: CF
authors.lastname: Bolwell
authors.forename: Christopher W
authors.initials: CW
authors.lastname: Rogers
authors.forename: Nigel P
authors.initials: NP
authors.lastname: French
authors.forename: Elwyn C
authors.initials: EC
authors.lastname: Firth
mesh_terms: D000367:Age Factors; D000818:Animals; D015331:Cohort Studies; D003132:Commerce; D005260:Female; D006734:Horse Diseases / Q000503:physiopathology*; D006736:Horses / Q000502:physiology*; D008297:Male; D008954:Models, Biological; D009520:New Zealand; D010805:Physical Conditioning, Animal; D012307:Risk Factors; D016019:Survival Analysis