Registered Thoroughbred Horses: What Colors Are Permitted?


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When I watched Thoroughbreds being saddled for a race, I noticed they were a lot of different colors. This made me wonder what colors are acceptable for Thoroughbred registration.

The American Jockey Club recognizes the following colors for Thoroughbred registration: black, white, chestnut, gray/roan, bay (brown), and palomino. Thoroughbreds can have white markings.

A lot of people choose a horse based on its color. Many factors determine a horse’s color, but does color determine how good a horse will become?

Approved colors for Thoroughbred registration.

The Jockey Club established standards for color registration. The following sections examine each color’s requirements and look into how coat colors have faired in racing history.

1. Black Thoroughbreds

A true black Thoroughbred is rare. Some people confuse a dark bay or dark chestnut color with black. For registration as a black Thoroughbred, the horse’s entire coat must be black, unless white markings are present.

picture of a black thoroughbred racehorse being put on a walker,

To distinguish a true black horse, look for dark brown eyes, black skin, and entirely black coats with no reddish or brown hair. It’s common for a black horse to “sun bleach” with exposure to the sun and sweat, resulting in a loss of some of the rich blackness of their coat.

Black foals are usually born a mousy gray, and many have primitive markings at birth, which disappear as black hair grows in. It’s common for a black foal to be mistaken for a grullo or even bay dun.

Black horses have at least one functional, dominant “E” allele and two copies of the non-functional, recessive “a” allele. A true black horse possesses at least one dominant extension gene (EE or Ee) and has no other dominant genes that further modify color.

Black Thoroughbreds on the race track

Because of their rarity, there are few true black Thoroughbred champions. Some people think the great filly Ruffian was a black horse, but they are incorrect.

She was a dark bay that looked black. Ruffians’ racing career started tremendously and ended tragically. She won her first ten races by huge margins.

This success set her on a path to meet Kentucky Derby winner Foolish Pleasure in a match race to settle, which was horse racing best Thoroughbred.

It’s estimated twenty million viewers tuned in to watch the race. Shortly after the start of the race, Ruffian shattered a leg bone but continued to run. Soon after the race, she was euthanized.

2. White Thoroughbreds

White Thoroughbreds are rare and are a historical symbol of power and fertility. For the Jockey Club to register a Thoroughbred white, the horse’s entire coat, including the mane, tail, and legs, is predominantly white and can not have any other colored hairs in its coat.

Horses with interspersed hair colors are registered as gray or roan horses. The first white Thoroughbred registered in the United States was a mare named White Beauty in 1963. Her progeny continues to produce white Thoroughbreds to the present date.

picture of a white thoroughbred looking out of its stall,

The white mare Beautiful Devil foaled a white filly on Feb. 5, 2017; the foal is a seventh-generation descendant of White Beauty. It’s believed that spontaneous mutations on the KIT gene are likely responsible for the white or mostly white color.

The mutations cause a range of coat colors from pure white and predominantly white with some brown patches. Some of the modifications are dominant, meaning the affected horses can pass the color on to their offspring.

White Thoroughbreds on the race track

White Thoroughbreds haven’t found much success on the race track; White Beauty won only twice from 16 starts. Further, there has never been a white Thoroughbred win a grade I stakes race in North America, but one did find success in Japan, a white Thoroughbred named Yuki-chan won three stakes races from 2008-2010.

3. Chestnut Thoroughbreds

To register as a chestnut, a horse can only display red hairs throughout their bodies. They can have no black hair. Their coat can vary in color from red-yellow to golden-yellow.

Chestnuts come in many different shades, but they are the same genetically. It is one of the most familiar colors of Thoroughbreds.

picture of a light chestnut thoroughbred,

Common chestnut colors include:

  • Dark (or liver) chestnut: A liver chestnut horse has a deep chocolate-colored body, mane, tail, and legs.
  • Flaxen chestnut: A flaxen chestnut is typically a liver chestnut with a straw-colored mane and tail.
  • Light(sandy) chestnut: Light chestnuts are the second most common chestnut shade. They are typically very pale red or strawberry blonde. Their mane and tails range from darker than coat color to blonde. A light chestnut could be mistaken for a palomino when their mane and tail are blonde.
  • Red chestnut: A red chestnut and a sorrel are the same; they have a deep red color similar to copper-penny with the same colored mane and tail.

Chestnut Thoroughbreds on the race track

The Triple Crown thoroughbred title is the most prestigious award in horse racing.  It is given to the three-year-old horse that wins the Kentucky Derby, Preakness Stakes, and the Belmont Stakes in the same year.

The competition started in 1875; however, there wasn’t a Triple Crown winner until Sir Barton, a chestnut colt, won it in 1919. To date, this feat has only been accomplished twelve more times, and chestnut-colored horses have won seven of the thirteen Triple Crown titles.

The following is a list of Chestnut Thoroughbreds that have won the Triple Crown:

picture of a dark chestnut thoroughbred during a race,
  • Sir Barton first horse to win the Triple Crown was a chestnut colt in 1919
  • Omaha was the third winner of the triple crown in 1935. He was a chestnut colt with a white blaze. 
  • Whirlawaythe fifth winner of the triple crown in 1937, was the son of Man O’ War widely regarded as the greatest racehorse at the time.
  • Assault the seventh winner of the triple crown in 1946. He is one of the most magnificent triple crown horses.
  • Secretariat ninth winner of the triple crown in 1973. He is considered the greatest racehorse of all time by many. He was nicknamed Big Red because of his deep chestnut coloring and large body.
  • Affirmed, the eleventh winner of the triple crown 1978. He is another strong chestnut he went on to have a great career and won the American Champion Three Year Old Male Horse award.
  • Justify a chestnut colt and winner of the thirteenth triple crown in 2018. Justify is only the second horse that won the Triple Crown without ever losing a race.  

4. Gray Thoroughbreds

Gray/Roan colored Thoroughbreds

Gray horses acquire their distinctive appearance from their black skin and a mixture of white and black hairs. Grey horses typically begin their life a darker color and gradually lighten as they age. Some will lighten so much they are mistaken for white.

picture of a gray thoroughbred at an auction,

Jockey Club requires a gray horse to have the majority of its coat, a mixture of black and white hairs. The mane, tail, and legs can be black or gray with or without white markings on their legs.

Roan, unlike gray, is a coloration pattern that remains constant throughout the life of the horse. Roan and Grey are completely different descriptors and are not interchangeable.

To register a Thoroughbred as a roan, the majority of the coat is interspersed with red and white or brown and white hairs. The mane, tail, and legs can be black, chestnut, or roan. The grey gene is dominant to any other inherited color, and the same is true of roan.

Gray/Roan Thoroughbreds on the race track 

Gray horses have seen plenty of success on the race tracks. The following is a list of the best gray racehorses in history, and all have been voted into the horse racings Hall of Fame.

  • Native Dancer won 21 out of 22 starts, and his only loss came in the 1953 Kentucky Derby. He was nicknamed The Gray Ghost because of his striking appearance. He was Horse of the Year in 1954. He was inducted into the Hall of Fame in 1963.
  • Spectacular Bid won 26 of 30 starts, including the Kentucky Derby and Preakness Stakes. He was inducted in the Hall of Fame in 1982.
  • Skip Away had career earnings over $9.6 million and won eight grade one stake races, including the 1997 Breeders’ Cup Classic. In 2004 Skip Away was voted into the Hall of Fame.
  • Silver Charm   Silver Charm won the Kentucky Derby and the Preakness and just missed winning the Triple Crown by three-quarters of a length. Silver Charm was inducted to the Hall of Fame in 2007. 
  • Holy Bull was champion three-year-old and Horse of the Year in 1994. In 2001 he was inducted into the Hall of Fame.
  • Lady’s Secret, nicknamed the “Iron Lady” had a racing career that spanned four years with 25 wins, including 12 grade one stake races and earned more than $3,000,000. Lady’s Secret is a member of the Hall of Fame.
  • Winning Colors won the Kentucky Derby to become only the third filly to accomplish this feat. She was inducted to the Hall of Fame in 2000.
  • Princess Rooney won her first ten races. She began racing as a two-year-old and won all six of her races. In her three-year-old campaign, she won five of her six races, including the Kentuck Oaks. She entered the Hall of Fame in 1991.

5. Bay Thoroughbreds

Bay Thoroughbreds have a reddish-brown coat with areas of tan on the shoulders, head, and flanks. The mane, tail, ear edges, and lower legs are black. The shades of bay horses vary by animal and is a standard Thoroughbred color.

Some think bay is a base color in horses. However, there are two base colors for horses, black and chestnut. Bay horses have a base color of black. All bay horses have a minimum of one gene that produces black pigments, the E allele gene.

Bay horses range in color from dark mahogany to creamy white. Dark bays/browns are often so dark they look black, but a bay can be distinguished.

If you notice brownish-red hairs under the horse’s eyes, around the muzzle, behind the elbow, or in front of the stifle, it’s a bay. A dark bay and liver chestnut look very similar, but a bay has black points, and a liver chestnut won’t.

Bay Thoroughbreds on the race track 

There’s no shortage of successful bay colored Thoroughbreds on the race track. Check out this list:

  • Seabiscuit the champion racehorse of the late 1930s, he captured the heart of America and along the way beat triple crown winner War Admiral in a match race. He also won Horse of the Year for 1938. Seabiscuit was a light bay Thoroughbred.
  • Northern Dancer: Northern Dancer won two legs of the Triple Crown, the Kentucky Derby, and Preakness. But being the most successful sire of the 20th century is his most significant contribution to Thoroughbred racing. Northern Dancer was a standard bay color.
  • Cigar:: When Cigar retired in 1996, he was the worlds leading money earner with winning close to 10 million dollars. He was voted racehorses of the decade for the 1990s was inducted into the Hall of Fame. Cigar was a dark bay.
  • Big Brown: Big Brown, like Northern Dancer, won two of the races of the Triple Crown, the Kentucky Derby, and Preakness Stakes. Before suffering a hoof injury, which led to his retirement, Big Brown won seven of the eight races he ran. He was named three-year-old champion colt in 2008.

6. Palomino Thoroughbreds

Palomino Thoroughbreds are rare but do occur and are recognized by The Jockey Club. A registered palomino Thoroughbred has a golden yellow coat with flaxen manes and tails.

A Palomino coat color can range from cream to dark gold. To create the Palomino color, a horse must have a chestnut base and a cream dilution gene.

The genotype ee creates a chestnut base coat color, and C Ccr at the C locus is the cream dilution gene. This combination changes the red coloring in the chestnut to a yellow pigment.

Palomino Thoroughbreds on the race track 

A palomino Thoroughbred that can compete on the racetrack is rare, and if someone is lucky enough to have one, they typically don’t race the horse for fear of it sustaining an injury. They sell for a lot of money as a novelty.

Unbelievably the only palomino to sell at the Keenland yearling auction occurred in 2009. But apparently, buyers didn’t have much faith in her ability because she sold for only $14,000, which is a low price at Keenland.

I found one horse that saw some success listed by some as a Palomino, Taiki Shuttle; he is a Japanese Thoroughbred. However, further research shows he is registered as chestnut, though he could pass for a Palomino.

Thoroughbred color facts

In the United States, the Jockey Club is the governing authority over the Thoroughbred breed registry.

Color is taken so seriously by this organization that if a foal’s color doesn’t match either of its parent’s then genetic blood testing may be required to determine if it can register as a Thoroughbred.

There is a vast set of rules and conditions a foal must meet to register as a Thoroughbred. Registration requirements range from the method of insemination to a horse’s coat color.

The most common Thoroughbred colors.

The most common Thoroughbred Color is bay

Eleven or more different genes determine the color of a horse’s coat. Of these eleven genes, two genes control the four basic coat colors—bay, brown, black, and chestnut.

picture of a bay thoroughbred racehorse during a race,

The remaining nine genes modify the basic colors by diluting them, overriding their effects, or creating distinctive pigmented areas. Interestingly, the genes that determine coat color also affect horse behavior, neurological function, and health.

Interestingly people associate horse color with temperament and chances of success on the track. There are sayings about color choices, one that comes to mind is “chestnut mare, buyer beware.” But success on the track has more to do with pedigree than color.

The most common Thoroughbred colors are bay, chestnut, and gray. These colors are the most successful runners in racing history. Is the color of their coat a factor in their athletic accomplishments? Or does the color of successful horses coincide with the colors that enter races?

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Miles Henry

I love animals! Especially horses, I've been around them most of my life but I am always learning more and enjoy sharing with others. I have bought, sold, and broke racehorse yearlings. I have raised some winning horses and had some that didn't make it as racehorses, so we trained them in other disciplines. Miles Henry

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