Horses used in racing today – and this is especially true of horses racing on the flat – do not look like, for example, the kind of horse that might be used to pull a rag-and-bone man’s cart or to deliver beer from brewery to pub. They look different because they are different. Racing horses are thoroughbreds; although that expression can be used to refer to any purebred horse, it should really be used only of horses of the Thoroughbred breed. Thoroughbreds excel at racing because they are fast, agile and spirited.
Today’s thoroughbred is rooted – like so much else in British racing – in England in the seventeenth and eighteenth centuries. Imported Oriental stallions were mated with native mares. Although the stallions could be of Turkoman or Barbary origin, the word universally used today is Arabian or Arab. Thoroughbreds have now spread around the world. The number today is huge; about 100,000 thoroughbred foals are registered worldwide each year, but all are descended from those few imported stallions.
The three stallions that began it all were:
The Byerley Turk (1680)
The Darley Arabian (1704)
The Godolphin Arabian (1729)
There have also been a number of others; it is thought that the total number of orientally bred stallions imported to this country amounted to about 160.
The General Stud Book of 1791 and the official registration of all thoroughbred horses are what have contributed to keeping the lines pure. Genetics have shown that 95% of male thoroughbreds can trace their ancestry back to the Darley Arabian, but when maternal inheritance is also taken into account, the Godolphin Arabian has the largest share, at 13.8% of all thoroughbreds.
The mares used in thoroughbred breeding have a much more diverse genetic inheritance, with many appearing to trace their line back to the thirteenth century. In any case, racehorses generally have a far better pedigree than most of those who bet on them.