What Makes a Thoroughbred

A potted history of thoroughbred horses

There are approximately 600 breeds of horse around the world, with the thoroughbred amongst the most popular.

Thoroughbreds are used for flat and jumps racing around the world, as they can maintain high speeds over extended distances.

Thoroughbreds were first developed in Great Britain during the 17th and 18th centuries. The most notable stallions (male horses) which helped create the breed were known as the Darley Arabian, the Godolphin Arabian and the Byerley Turk.

These three were imported to England in the early part of the 17th century, and nearly all modern-day thoroughbred horses are descended from these stallions. The stallions were bred with much stronger, but less developed, British mares (female horses).

During the 17th century, the lineage of horses was recorded in the General Stud Book in Britain and has been continued to this day. The Australian Stud Book was created in 1878 and bought by Racing Information Services Australia (RISA) in 2014. These stud books help provide information on the population and breeding statistics of thoroughbreds.

Typically, a thoroughbred’s racing career starts at the age of two, and a small number of horses – especially jumps horses – can continue racing until the ripe old age of ten or even 12.

Jumps horses tend to start racing around two years later than their flat counterparts, to enable their powerful hind legs to fully develop.

Another characteristic of the thoroughbred is the size of its heart, which typically weighs around one per cent of the horse’s total body weight. Whilst galloping, a horse’s heart rate can reach up to 240 beats per minute:

Terms typically associated with thoroughbred horses are as follows:

  • Colt – a young male horse up to the age of four
  • Filly – a young female horse up to the age of four
  • Stallion – a male horse used for breeding
  • Mare – a female horse aged five or older
  • Broodmare – a female horse used for breeding
  • Foal – a newborn horse up to one year old
  • Sire – the foal’s father
  • Dam – the foal’s mother
  • Yearling – a one-year-old horse
  • Gelding – a castrated male horse (usually to make it more even-tempered)
  • Maiden – a horse that is yet to win a race