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An Investigation Of Thoroughbred Growth, Radiographic Findings, Sales And Racing Performance



A pilot study was recently conducted which investigated the growth, radiographic findings, sales and subsequent racing performance of 248 Thoroughbreds born in 2013-2017 and raised in Central Kentucky on 6 different farms. This study identified some interesting correlations between an individual’s size relative to the population, notable radiographic findings, sales results, and racing performance. While it supported many of our previous theories, it also created a number of new questions.


Now, we would like to increase the number of horses in the study in order to gain greater statistical power, minimizing the risk of individual farm effects from skewing the results of the pilot study, and enabling further analysis of subpopulations.
We would also like to expand the study to include data from the industries in Europe and Australia to allow for analysis of any regional differences. We hope to do this through the inclusion of retrospective growth, radiographic, sales, and racing data for Thoroughbreds born between 2007 and 2017 and raised in Kentucky, Europe, and Australia.


To be included in the study, we need the following data for each individual:

  • Growth Data - Complete weight and height records from birth through to sale or going into training. Weights must have been measured with a scale. Only individuals that have measurements within each of the following periods should be included: (1) foal: 0-30 days of age; (2) suckling: 31-180 days; (3) weanling: 181-365 days; and (4) yearling: 366-640 days.
  • Radiographic records – Radiographic reports from survey radiographs taken early in the yearling year as well as the report for pre-sale radiographs (for horses that were entered in an auction as a yearling). The date that the radiographs were taken should be recorded for each set.
  • If there are significant findings within the radiographs, please note:
    • if the issue resolved on its own; or
    • if surgical repair was undertaken and the date and nature of the procedure; and
    • if the individual was withdrawn from a sale due to the finding.


  • Breeding date - This will allow for the calculation of length of gestation which will have had an effect on foal birth weight.
  • Notation of foals from maiden mares - This can be achieved by indicating the number of previous foals the mare has had within the foal’s information in Gro-trac® (see Info tab).
  • Identify foals with significant post-foaling complications
  • Notation of weaning date
    • Turnout and confinement protocols for:
      January-March born foals
      April-June born foals
    • Typical feeding programs for mares foaling in:


For future foal crops, in addition to the above, we would like the opportunity to:

- Identify foals that have experienced confinement of 7 days or more, including the reason for confinement and the schedule taken to resume normal activity. Please consider adding this to your record-keeping.

- Learn about mare weight changes during the 3rd trimester and during lactation. Any farms that are willing to contribute to this by weighing their mares over this period are asked to contact us.