Stephanie A. Preston, MSc, Troy N. Trumble, DVM, PhD, Dana N. Zimmel, DVM, Terese L. Chmielewski, PhD, Murray P. Brown, DVM, MSc, Jorge A. Hernandez, DVM, MPVM, PhD

J Am Vet Med Assoc 2008; 232:85–90 

Objective: To characterize lameness during training and compare exercise variables and financial returns among yearling Thoroughbreds that were bought for the purpose of resale for profit.

Animals: 40 yearling Thoroughbreds.

Design: Prospective study.

Procedures: Horses purchased at yearling sales (summer 2004) were trained prior to resale at 2-year-olds in training sales (spring 2005). Horses were monitored daily for diagnosis and treatment of lameness during training. Selected variables, including sex, age, purchase price, lameness, distance (No. of furlongs) galloped during training, and financial returns, were compared among horses that had performance speeds (assessed at 2-year-olds in training sales) classified as fast, average, or slow.

Results: 37 of 40 horses became lame during training, most commonly because of joint injury. Eighteen of the lame horses had hind limb injuries only; 5 horses had injuries in forelimbs and hind limbs. The frequency of new cases of lameness increased as the date of the 2-year-olds in training sales approached. At the sales, 4, 21, and 15 horses were classified as fast, average, or slow, respectively; median financial return was slightly (but significantly) different among horses classified as fast ($14,000), average ($0), or slow (–$8,000).

Conclusions and Clinical Relevance: Incidence of lameness during training in yearling horses purchased for the purpose of resale for profit was high. Lameness more commonly affected hind limbs than forelimbs and was attributable to joint injury in most horses. Financial returns differed between horses classified as fast and average or slow at the 2-year-olds in training sales.