The Thoroughbred is a horse breed developed for horse racing. Although the word thoroughbred is sometimes used to refer to any breed of purebred horse, it technically refers only to the Thoroughbred breed. Thoroughbreds are considered "hot-blooded" horses that are known for their agility, speed, and spirit.
The Thoroughbred, as it is known today, was developed in 17th- and 18th-century England, when native were Crossbreed with imported stallions of Arabian horse, Barb horse, and Turkoman horse breeding. All modern Thoroughbreds can trace their pedigrees to three stallions originally imported into England in the 17th and 18th centuries, and to a larger number of foundation mares of mostly English breeding. During the 18th and 19th centuries, the Thoroughbred breed spread throughout the world; they were imported into North America starting in 1730 and into Australia, Europe, Japan and South America during the 19th century. Millions of Thoroughbreds exist today, and around 100,000 are registered each year worldwide.
Thoroughbreds are used mainly for racing, but are also bred for other riding disciplines such as show jumping, Eventing, dressage, polo, and fox hunting. They are also commonly crossbred to create new breeds or to improve existing ones, and have been influential in the creation of the Quarter Horse, Standardbred, Anglo-Arabian, and various warmblood breeds.
Thoroughbred racehorses perform with maximum exertion, which has resulted in high accident rates and health problems such as bleeding from the lungs. Other health concerns include low fertility, abnormally small hearts, and a small hoof-to-body-mass ratio. There are several theories for the reasons behind the prevalence of accidents and health problems in the Thoroughbred breed, and research on the subject is ongoing.
Thoroughbreds born in the Northern Hemisphere are officially considered a year older on the first of January each year; those born in the Southern Hemisphere officially are one year older on the first of August. These artificial dates have been set to enable the standardization of races and other competitions for horses in certain age groups.Phifer Track Talk p. 38
Under Charles II, a keen racegoer and owner, and Anne, royal support was given to racing and the breeding of race horses. With royal support, horse racing became popular with the public, and by 1727, a newspaper devoted to racing, the Racing Calendar, was founded. Devoted exclusively to the sport, it recorded race results and advertised upcoming meets.Wall Famous Running Horses pp. 7–8
Each of the three major foundation sires was, coincidentally, the ancestor of a grandson or great-great-grandson who was the only male descendant to perpetuate each respective horse's male line: Matchem was the only descendant of his grandsire, the Godolphin Arabian, to maintain a Patrilineality to the present;Milner The Godolphin Arabian p. 140 the Byerley Turk's male line was preserved by Herod (or King Herod), a great-great-grandson;Willett The Thoroughbred pp. 38–39 and the male line of the Darley Arabian owes its existence to great-great-grandson Eclipse, who was the dominant racehorse of his day and never defeated.Willett The Thoroughbred p. 37 One genetic study indicates that 95% of all male Thoroughbreds trace their direct male line (via the Y chromosome) to the Darley Arabian.
However, in modern Thoroughbred pedigrees, most horses have more crosses to the Godolphin Arabian (13.8%) than to the Darley Arabian (6.5%) when all lines of descent (maternal and paternal) are considered. Further, as a percentage of contributions to current Thoroughbred bloodlines, Curwen's Bay Barb (4.2%) appears more often than the Byerley Turk (3.3%). The majority of modern Thoroughbreds alive today trace to a total of only 27 or 28 stallions from the 18th and 19th centuries.
Selective breeding for speed and racing ability led to improvements in the size of horses and winning times by the middle of the 19th century. Bay Middleton, a winner of the Epsom Derby, stood over 16 hands high, a full hand higher than the Darley Arabian. Winning times had improved to such a degree that many felt further improvement by adding additional Arabian bloodlines was impossible. This was borne out in 1885, when a race was held between a Thoroughbred, Iambic, considered a mid-grade runner, and the best Arabian of the time, Asil. The race was over , and although Iambic was handicapped by carrying more than Asil, he still managed to beat Asil by 20 lengths.Willett The Classic Racehorse pp. 39–41 The improvement of the breed for racing in this way was said by noted 19th century racing writer, Nimrod, to have created "the noblest animal in the creation".
An aspect of the modern British breeding establishment is that they breed not only for flat racing, but also for steeplechasing.Willett The Classic Racehorse p. 57 Up until the end of the 19th century, Thoroughbreds were bred not only for racing but also as saddle horses.Derry Horses in Society p. 41
Soon after the start of the 20th century, fears that the English races would be overrun with American-bred Thoroughbreds because of the closing of US racetracks in the early 1910s, led to the Jersey Act of 1913.Willett The Classic Racehorse pp. 111–113 It prohibited the registration of any horse in the General Stud Book (GSB) if they could not show that every ancestor traced to the GSB. This excluded most American-bred horses, because the 100-year gap between the founding of the GSB and the American Stud Book meant that most American-bred horses possessed at least one or two crosses to horses not registered in the GSB. The act was not repealed until 1949, after which a horse was only required to show that all its ancestors to the ninth generation were registered in a recognized Stud Book.Willett The Classic Racehorse pp. 71–74 Many felt that the Jersey Act hampered the development of the British Thoroughbred by preventing breeders in the United Kingdom from using new bloodlines developed outside the British Isles.Willett The Classic Racehorse p. 56
Messenger left little impact on the American Thoroughbred, but is considered a foundation sire of the Standardbred breed. Diomed, who won the Derby Stakes in 1780, had a significant impact on American Thoroughbred breeding, mainly through his son Sir Archy.Montgomery The Thoroughbred pp. 131–136 John F. Wall, a racing historian, said that Sir Archy was the "first outstanding stallion we can claim as native American."Wall Famous Running Horses pp. 114–115 He was retired from the racetrack because of lack of opponents. Medley and Shark, who arrived in the United States before Messenger and Diomed, became important broodmare and dam sires by producing foundation stock, and their daughters and granddaughters were bred primarily to Diomed.
After the American Revolution, the center of Thoroughbred breeding and racing in the United States moved west. Kentucky and Tennessee became significant centers. Andrew Jackson, later President of the United States, bred and raced Thoroughbreds at his Hermitage Plantation near Nashville, Tennessee.Montgomery The Thoroughbred pp. 142–143 Match races held in the early 19th century helped to popularize horse racing in the United States. One took place in 1823, in Long Island, between Sir Henry and American Eclipse. Another was a match race between Boston and Fashion in 1838 that featured bets of $20,000 from each side.Montgomery The Thoroughbred pp. 143–147 The last major match races before the American Civil War were both between Lexington and Lecompte. The first was held in 1854 in New Orleans and was won by Lecompte. Lexington's owner then challenged Lecompte's owner to a rematch, held in 1855 in New Orleans and won by Lexington. Both of these horses were sons of Boston, a descendant of Sir Archy.Montgomery The Thoroughbred pp. 152–154 Lexington went on to a career as a breeding stallion, and led the sires list of number of winners for sixteen years, fourteen of them in a row.Wall Famous Running Horses p. 119
After the American Civil War, the emphasis in American racing changed from the older style of four-mile (6 km) races in which the horses ran in at least two heats. The new style of racing involved shorter races not run in heats, over distances from five up to . This development meant a change in breeding practices, as well as the age that horses were raced, with younger horses and sprinters coming to the fore. It was also after the Civil War that the American Thoroughbred returned to England to race. Iroquois became the first American-bred winner of the Epsom Derby in 1881. The success of American-bred Thoroughbreds in England led to the Jersey Act in 1913, which limited the importation of American Thoroughbreds into England.Willett The Thoroughbred pp. 159–163 After World War I, the breeders in America continued to emphasize speed and early racing age but also imported horses from England, and this trend continued past World War II.Willett The Thoroughbred pp. 165–171 After World War II, Thoroughbred breeding remained centered in Kentucky, but California, New York, and Florida also emerged as important racing and breeding centers.Willett The Thoroughbred pp. 175–176
Thoroughbreds in the United States have historically been used not only for racing but also to improve other breeds. The early import Messenger was the foundation of the Standardbred,Evans The Horse pp. 28–29 and Thoroughbred blood was also instrumental in the development of the American Quarter Horse.Evans The Horse pp. 23–27 The foundation stallion of the Morgan horse breed is held by some to have been sired by a Thoroughbred.Evans The Horse p. 36 Between World War I and World War II, the U.S. Army used Thoroughbred stallions as part of their Remount Service, which was designed to improve the stock of cavalry mounts.Derry Horses in Society pp. 136–137Buecker Fort Robinson pp. 27–29
Organized racing in Italy started in 1837, when race meets were established in Florence and Naples and a meet in Milan was founded in 1842. Modern flat racing came to Rome in 1868. Later importations, including the Derby Stakes winners Ellington (1856) and Melton (1885), came to Italy before the end of the 19th century.Willett The Thoroughbred pp. 180–82 Modern Thoroughbred breeding in Italy is mostly associated with the breeding program of Federico Tesio, who started his breeding program in 1898. Tesio was the breeder of Nearco, one of the dominant sires of Thoroughbreds in the later part of the 20th century.Willett The Thoroughbred pp. 182–187
Other countries in Europe have Thoroughbred breeding programs, including Germany,Willett The Classic Racehorse pp. 162–169 Russia, Poland, and Hungary.Willett The Classic Racehorse pp. 202–211
Unlike a significant number of registered breeds today, a horse cannot be registered as a Thoroughbred (with The Jockey Club registry) unless conceived by live cover, the witnessed natural horse breeding. Artificial insemination (AI) and embryo transfer (ET), though commonly used and allowable in many other horse breed registries, cannot be used with Thoroughbreds. One reason is that a greater possibility of error exists in assigning parentage with artificial insemination, and although DNA and blood testing eliminate many of those concerns, artificial insemination still requires more detailed record keeping.Equine Research Breeding Management and Foal Development p. 349 The main reason, however, may be economic; a stallion has a limited number of mares who can be serviced by live cover. Thus the practice prevents an oversupply of Thoroughbreds, although modern management still allows a stallion to live cover more mares in a season than was once thought possible. As an example, in 2008, the Australian stallion Encosta De Lago covered 227 mares. Australian Stud Book: Encosta De Lago (AUS), Australian Jockey Club Limited and Victoria Racing Club Limited Retrieved 2009-1-25 By allowing a stallion to cover only a couple of hundred mares a year rather than the couple of thousand possible with artificial insemination, it also preserves the high prices paid for horses of the finest or most popular lineages.
Concern exists that the closed stud book and tightly regulated population of the Thoroughbred is at risk of loss of genetic diversity because of the level of inadvertent inbreeding inevitable in such a small population. According to one study, 78% of in the current population can be traced to 30 foundation animals, 27 of which are male. Ten foundation mares account for 72% of maternal (tail-female) lineages, and, as noted above, one stallion appears in 95% of lineages. Thoroughbred pedigrees are generally traced through the Mother line, called the distaff line. The line that a horse comes from is a critical factor in determining the price for a young horse.Napier Blood will tell pp. 17–18
Averages, however, can be deceiving. For example, at the 2007 Fall Yearling sale at Keeneland, 3,799 young horses sold for a total of $385,018,600, for an average of $101,347 per horse. However, that average sales price reflected a variation that included at least 19 horses that sold for only $1,000 each and 34 that sold for over $1,000,000 apiece.
The highest price paid at auction for a Thoroughbred was set in 2006 at $16,000,000 for a two-year-old colt named The Green Monkey. Record prices at auction often grab headlines, though they do not necessarily reflect the animal's future success; in the case of The Green Monkey, injuries limited him to only three career starts before being retired to stud in 2008, and he never won a race. Conversely, even a highly successful Thoroughbred may be sold by the pound for a few hundred dollars to become horsemeat. The best-known example of this was the 1986 Kentucky Derby winner Ferdinand, exported to Japan to stand at stud, but was ultimately slaughtered in 2002, presumably for pet food.
However, the value of a Thoroughbred may also be influenced by the purse money it wins. In 2007, Thoroughbred racehorses earned a total of $1,217,854,602 in all placings, an average earnings per starter of $16,924. In addition, the track record of a race horse may influence its future value as a breeding animal.
Stud fees for stallions that enter breeding can range from $2,500 to $500,000 per mare in the United States, and from £2000 to £75,000 or more in Britain. The record stud fee to date was set in the 1980s, when the stud fee of the late Northern Dancer reached $1 million. During the 2008 Australian breeding season seven stallions stood at a stud fee of A$110,000 or more, with the highest fee in the nation at A$302,500.
In 2007, there were 71,959 horses who started in races in the United States, and the average Thoroughbred racehorse in the United States and Canada ran 6.33 times in that year. In Australia, there were 31,416 horses in training during 2007, and those horses started 194,066 times for A$375,512,579 of prize money. During 2007, in Japan, there were 23,859 horses in training and those horses started 182,614 times for A$857,446,268 of prize money. In Britain, the British Racing Authority states there were 8,556 horses in training for flat racing for 2007, and those horses started 60,081 times in 5,659 races.
Statistically, fewer than 50% of all race horses ever win a race, and less than 1% ever win a stakes race such as the Kentucky Derby or Epsom Derby. Any horse who has yet to win a race is known as a maiden.
Horses finished with a racing career that are not suitable for breeding purposes often become riding horses or other equine companions. A number of agencies exist to help make the transition from the racetrack to another career, or to help find retirement homes for ex-racehorses.
Thoroughbreds have been foundation bloodstock for various Warmblood breeds due to their refinement and performance capabilities. Crossbred horses developed from Thoroughbreds, (informally categorized as "hot bloods" because of temperament) crossed on sturdy draft horse breeds, (classified as "cold bloods" for their more phlegmatic temperament) are known as "warmbloods," which today are commonly seen in competitive events such as show jumping and dressage. Examples include the Dutch Warmblood, Hanoverian horse, and Selle Français. Some warmblood registries note the percentage of Thoroughbred breeding, and many warmblood breeds have an open stud book that continues to allow Thoroughbred crossbreeding.
One tenth of all Thoroughbreds suffer orthopedic problems, including fractures. Current estimates indicate that there are 1.5 career-ending breakdowns for every 1,000 horses starting a race in the United States, an average of two horses per day. The state of California reported a particularly high rate of injury, 3.5 per 1000 starts.Rosenblatt "Barbaro's Legacy" Washington Post Other countries report lower rates of injury, with the United Kingdom having 0.9 injuries/1,000 starts (1990–1999) and the courses in Victoria, Australia, producing a rate of 0.44 injuries/1,000 starts (1989–2004).Oke, "Understanding and Preventing Catastrophic Injuries", The Horse, 26–36. Thoroughbreds also have other health concerns, including a majority of animals who are prone to bleeding from the lungs (exercise induced pulmonary hemorrhage), 10% with low fertility, and 5% with abnormally small hearts. Thoroughbreds also tend to have smaller hooves relative to their body mass than other breeds, with thin soles and walls and a lack of cartilage mass, which contributes to foot soreness, the most common source of lameness in racehorses.Arthur Diagnosis and Management of Lameness in the Horse p. 872
Poor breeding may be encouraged by the fact that many horses are sent to the breeding shed following an injury. If the injury is linked to a conformational fault, the fault is likely to be passed to the next generation. Additionally, some breeders will have a veterinarian perform straightening procedures on a horse with crooked legs. This can help increase the horse's price at a sale and perhaps help the horse have a sounder racing career, but the genes for poor legs will still be passed on.
Studies have shown that track surfaces,Oikawa "Effect of restructuring of a racetrack on the occurrence of racing injuries in thoroughbred horses" Journal of Equine Veterinary Science with toe grabs, use of certain legal medications, and high-intensity racing schedules may also contribute to a high injury rate.Pedulla "Injury steps up scrutiny on Triple Crown Schedule" USA Today One promising trend is the development of synthetic surfaces for racetracks, and one of the first tracks to install such a surface, Turfway Park in Florence, Kentucky, saw its rate of fatal breakdowns drop from 24 in 2004–05 to three in the year following Polytrack installation. The material is not perfected, and some areas report problems related to winter weather, but studies are continuing.
Whenever a racing accident severely injures a well-known horse, such as the major leg fractures that led to the euthanization of 2006 Kentucky Derby winner Barbaro, or 2008 Kentucky Derby runner-up Eight Belles, animal rights groups have denounced the Thoroughbred racing industry. On the other hand, advocates of racing argue that without horse racing, far less funding and incentives would be available for medical and biomechanical research on horses. Although horse racing is hazardous, veterinary science has advanced. Previously hopeless cases can now be treated, and earlier detection through advanced imaging techniques like Nuclear medicine can keep at-risk horses off the track.Mackey "Stress fractures of the humerus, radius and tibia in horses" Veterinary Radiology
Foundation mares
Later development in Britain
In America
In Europe
In Australia and New Zealand
In other areas
Registration, breeding, and population
Value
Uses
Horse racing
Other disciplines
Crossbreeding
Health issues
Selective breeding
Excess stress
Medical challenges
See also
Notes
Footnotes
External links
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