Why don't we see more fillies in the Triple Crown races?

Pick Pony | March 25, 2024, 6:17 p.m.

Only 11 fillies have won a Triple Crown race, with the most recent being Rachel Alexandra at the Preakness in 2009. It's become rare to even see a female horse entered in the sport's three marquee events. The Kentucky Derby's points-based qualification system, introduced in 2013, requires any filly hoping to run in the race, usually held on the first Saturday in May at Churchill Downs, to compete against colts in pre-Derby qualifiers, potentially before they are physically ready. Why are there so few fillies in horse racing’s biggest events?

"Day in and day out, a colt is heavier and more able to withstand the rigors of training at that age," said Rick Arthur, equine director at both the UC Davis School of Veterinary Medicine and the California Horse Racing Board, in 2016. "Fillies don't really catch up with colts until near the end of their 3-year-old career."

Others however, disagree.

"Gender doesn't matter," said Jess Jackson, thoroughbred Rachel Alexandra's co-owner. "A thoroughbred wants to run. If a filly is as good as the colts, she ought to compete."

The underrepresentation of fillies, or young female horses, in horse racing when compared to colts, or young male horses, is a multifaceted issue that primarily stems from certain breeding practices.

In the world of horse breeding and racing, fillies are often valued more for their ability to produce offspring than for their racing capabilities. This is because a mare can only give birth to a limited number of foals in her lifetime, making each foal more valuable than the prior one. As such, fillies are often retired from racing at an earlier age to become broodmares, or breeding mares, to preserve their health for reproduction. This practice significantly reduces the number of fillies that continue in competitive racing.

Additionally, there is a belief within some circles in the racing industry that fillies are not as physically robust as colts. They believe fillies are more prone to injuries due to their physical constitution. They believe that the physical demands of racing are too strenuous for fillies, potentially leading to shorter racing careers and higher risks during races. However, not every agrees with this assessment. There are many examples of successful and robust fillies in the history of horse racing, and many experts argue that the physical differences between colts and fillies do not significantly impact their racing capabilities.

Some famous fillies who have won major horse racing events include:

  • Ruffian: Known as one of the greatest fillies in horse racing history, she won all ten of her races before her career was tragically cut short.
  • Winning Colors: One of only three fillies to win the Kentucky Derby, she accomplished this feat in 1988.
  • Rachel Alexandra: She won the Preakness Stakes in 2009, becoming the first filly to do so in 85 years.
  • Zenyatta: She had an impressive career, winning 19 of her 20 races, including the Breeders' Cup Classic.