What Type of Horses Are In The Kentucky Derby?

According to the Kentucky Derby’s website, there are very specific qualifications for which horses are chosen to race in the Kentucky Derby: the horses must be three years old and Thoroughbred racehorses. When does a Thoroughbred’s birthday have to fall to put them at the three-year mark? What gender of horse participates in the Kentucky Derby? Read on to find out.

When Does A Horse’s Birthday Need to Fall in Order to Race?

Horses must be three years old to participate in the Kentucky Derby. But what if their birthday falls somewhere in the middle of the event?

When it comes to Thoroughbred horses, there is no chance of a birthday falling in the middle of the Kentucky Derby because every Thoroughbred has the same official birthday: January 1st. Though this is not the actual birthday of all Thoroughbred horses, they are all registered as having the same birth date.

However, most foals are born anywhere from May-October. How does this work with the January 1st birthday? If a foal is born before January 1st, even by one day, it is automatically considered one year old. This gives that foal far less time to train than its peers born on or after the new year. Since the date a mare gives birth can drastically impact how a horse will race in the derby, many breeders use artificial means to try and control when a foal will be born, such as using artificial sunlight to ramp up the reproductive cycle.

Why Do Kentucky Derby Horses Share the Same Birthdate?

The tradition began with the British and came to America with colonists. However, all Northern Hemisphere Thoroughbreds were originally said to be born on May Day, or May 1st. Later on, members of the Jockey Club in Britain decided to change the date to January 1st. However, this only applied to Newmarket horses, as the other racing faction in England kept the May 1st date.

There was a similar divide in the United States over the date. The North adopted the January 1st date, while the South stuck with May 1st. Until the Civil War, the divide remained. Afterward, the January 1st date was adopted countrywide.

What Gender of Horse Races in the Kentucky Derby?

Both male and female horses race in the Kentucky Derby. However, only three female horses (also known as fillies) have won the Kentucky Derby. Those horses were Regret in 1915, Genuine Risk in 1980, and Winning Colors in 1988. This means that other than these three fillies, male horses have typically won the Kentucky Derby. However, this number may simply reflect that male horses are entered into the derby more than female horses.