Q. I know it’s common practice to start Thoroughbreds racing at 2. But Justify didn’t make his first start until he was 3 and won the Triple Crown. Does this mean we shouldn’t start racing horses until they’re older?

Tina, via e-mail

A. There are many factors which influence when a horse is started in training. These include date of birth, degree of skeletal maturity, athletic ability, as well as the preferences of the owner or trainer.

I am not aware of any data that specifically says starting a horse at 2 is detrimental; in fact, training the horse’s skeleton to race speeds at the age of 2 may lead to less injury than starting as an older horse.

Changes in skeletal structures are very dependent to exercise loads, and age differences become less important over time. A study published by Tanner et al. in the Equine Veterinary Journal in 2013¹ found that, in a group of over 4,500 New Zealand Thoroughbred racehorses, racing as a 2-year-old had a strong association with positive racing career outcomes, including total number of starts and years raced. The researchers speculated that horses trained to race as 2-year-olds may have better musculoskeletal health throughout life than horses that are placed in training or racing at a later age.

Justify has demonstrated himself as a superior horse by breaking the “curse of Apollo,” winning six races this year, and becoming only the second undefeated Triple Crown Winner. Whether or not waiting to make your first start as a 3-year-old will become the norm, I don’t know, but it certainly appears that his connections made all the right moves with him.

¹Tanner JC, Rogers CW, and Firth EC (2013), The association of 2‐year‐old training milestones with career length and racing success in a sample of Thoroughbred horses in New Zealand. Equine Veterinary Journal, 45: 20-24. doi:10.1111/j.2042-3306.2011.00534.x