In the Northern Hemisphere, all thoroughbred horses have the same official birthday on January 1, regardless of their actual birth date. In the southern hemisphere, all thoroughbred horses share an August 1 birthday. The goal of giving all thoroughbred horses the same official birthday is to more accurately categorize them by age for racing purposes. This birthday rule means that a horse born in mid-December would officially turn 1 year old less than a month later, on January 1st. Breeders normally try to have their horses born as soon as possible after the official date in order to have as much time as possible to train them for the race. Once a thoroughbred horse reaches its second birthday, it is usually eligible for racing.
More about horses:
Horses cannot breathe through their mouths – only through their noses.
A horse expends more energy when lying on the ground than when standing.
Thoroughbred horses can run at a top speed of over 40 miles per hour (65 km/h).