A pinto horse has a coat color that consists of large patches of white and any other color. The distinction between "pinto" and "solid" can be tenuous, as so-called "solid" horses have areas of white hair. Various cultures throughout history appear to have selectively bred for pinto patterns. Many breeds of horses carry pinto patterns. Pinto coloring, known as "coloured" in nations using British English, is the most popular in the United States. While pinto colored horses are not considered as a "breed," several competing color breed registries have formed to encourage the breeding of pinto colored horses; the word "paint" is sometimes used to describe pinto horses but today, it is used for the American Paint Horse. Pinto patterns are visually and genetically distinct from the leopard complex spotting patterns characteristic of horse breeds such as the Appaloosa. Breeders who select for color are careful not to cross the two patterns, registries that include spotting color preferences will refuse registration to horses that exhibit characteristics of the "wrong" pattern.
The word "pinto" is Spanish for'painted', also'dappled' or'spotted'. While pinto coloration has yet to be identified as a wildtype by DNA studies or seen in cave art predating horse domestication, images from pottery and other art of ancient antiquity show horses with flashy spotted patterns, indicating that they may have been desirable traits and selectively bred for. Images of spotted horses appear in the art of Ancient Egypt, archaeologists have found evidence of horses with spotted coat patterns on the Russian steppes before the rise of the Roman Empire. Spotted horses were among those brought to the Americas by the Conquistadors. By the 17th century in Europe, spotted horses were quite fashionable, though when the fad ended, large numbers of newly-unsellable horses were shipped to the Americas, some of which were sold while others were turned loose to run wild; the color became popular among Native Americans, was bred for in the United States, which now has the greatest number of pinto horses in the world.
There are a number of words which describe the various color and spotting patterns of pinto horses. A pinto horse is genetically created when an allele for a spotting pattern is present; the genes that create the underlying base coat color are not related to the genes that create white spotting. The precise mechanisms that create spotting are not all understood, but those that are known have human parallels, such as piebaldism. What horse terminology describes as "pinto" or "coloured" has been called leucism or "partial albinism" by pigment researchers. Common terms for describing different types of pinto horses include: Piebald:. Any pinto pattern on a black base coat, thus a black-and-white spotted horse. Skewbald:. Any pinto pattern on any base coat other than black; as chestnut and bay are the most common base coat colors, skewbalds are most chestnut and white or bay and white. At one time, the term may have applied more to brown-looking pinto horses, but today it encompasses any color other than black.
Coloured: The term for pinto coloration in nations using British English, including both piebald and skewbald. Tricolored or Tricoloured: a term for horse with three colors, in nations using British English, it is incorporated into the term skewbald. Tobiano: The most common type of pinto, tobiano is a spotting pattern characterized by rounded markings with white legs and white across the back between the withers and the dock of the tail arranged in a vertical pattern and more white than dark, though the ideal is a 50-50 distribution, with the head dark, having markings seen on a non-pinto horse. I.e. star, strip, or blaze. Tobiano is a simple dominant trait caused by a single gene and therefore all tobiano horses have at least one tobiano parent. A DNA test exists for tobiano. Tobiano is not associated with any health concerns. Overo: A collective term used by the American Paint Horse Association, overo means "pinto, but not tobiano." It denotes patterns produced by at least three different genetic mechanisms: frame, splashed white or sabino, described below.
These patterns are characterized by irregular markings with more jagged edges than tobiano markings. The white crosses the back. While some currently-identified overo patterns appear to be dominant or incomplete dominant traits, overo-patterned foals are produced from two solid-colored parents. Frame or frame overo: Frame is a popular and recognized type of non-tobiano pinto; this spotting pattern, in the absence of genes for other patterns, is characterized by horizontally-oriented white patches with jagged, crisp edges. White patches include the head and lateral aspects of the neck and body, the eyes can be blue. Frame overos may have modest markings that are not "pinto." This quality allows the pattern to "hide" for generations, is thought to be responsible for some cases of "cropouts." Frame is an incomplete dominant trait. However, foals born with two copies die shortly after birth. N/O frame horses do not have any known health defe
Sabino is a group of white spotting patterns in horses that affect the skin and hair. A wide variety of irregular color patterns are accepted as sabino. In the strictest sense, "sabino" refers to the white patterns produced by the Sabino 1 gene, for which there is a DNA test. However, other horse enthusiasts refer to patterns that are visually similar to SB1 as "sabino" if testing indicates the gene is not present. Use of the term to describe non-SB1 "sabino" patterns in breeds that do not carry the gene is hotly debated by both researchers and horse breeders. Sabino patterning is visually recognized by roaning at the edges of white markings, belly spots, irregular face markings white extending past the eyes or onto the chin, white above the knees or hocks, "splash" or "lacy" marks anywhere on the body, but on the belly; some sabinos have patches of roan patterning on part of the body the barrel and flanks. Some sabinos may have a dark leg or two. Both blue and brown eyes are seen. At one end of the sabino spectrum, the SB1 gene, when homozygous, can produce a horse, completely white with pink or only pigmented skin.
Some forms of sabino genetics are thought to be the most common reason for solid-colored horses with "chrome", a term which can refer to horses with bold white markings on the face and high white leg markings. The most generous definition of sabino can include horses with as little white as a chin or lower lip spot. Though horses with the Sabino 1 gene can be white, no forms of sabino are linked to lethal white syndrome. Sabino 1 was identified in 2005 by researchers at the University of Kentucky; the Sabino 1 gene, the associated spotting pattern, is found in Miniature horses, American Quarter Horses, American Paint Horses, Tennessee Walkers, Missouri Fox Trotters, Shetland Ponies, Aztecas. SB1 is notably absent from the Arabian horse, Standardbred horse, Shire horse and Clydesdale. There are many proposed genes responsible for the sabino-like white spotting in these and other breeds. Researchers gave the allele they discovered the name "Sabino 1" with the expectation of finding genes yet to be named "Sabino 2", "Sabino 3", so on.
However, the next allele to be discovered on KIT caused a dominant white phenotype, so was given the name W1. After that, all other alleles found at the KIT locus were given names in the W series the ones that would better be described as sabino than dominant white; as a result, it is unlikely that a Sabino 2 will be named. If more sabino alleles are found in the future, they will most be given names in the W series. Though horses with the Sabino 1 gene can be white, neither Sabino 1 or any other forms of sabino are linked to lethal white syndrome. Foals afflicted with LWS are born white or near-white, but have a defective colon and invariably die within 72 hours of birth. A DNA test exists for Lethal White Syndrome to identify carriers. Horses with one copy of the Sabino 1 gene are said to be heterozygous for that gene, have a distinctive white spotting pattern; the areas of pigmentless white hair are rooted in pigmentless pink skin. Horses with the Sabino 1 pattern have irregular, rough-edged white patches on the extremities and the face.
These white patches often include the midsection as "belly spots". Interspersed white hairs around the white markings or on the body, which can resemble roan, are characteristics of Sabino 1 when heterozygous. Sabino 1 horses have two or more white feet or legs, a blaze, spots or roaning on the belly or flanks, jagged margins to white markings. Modest Sabino 1 markings are difficult to tell apart from other white markings. Blue eyes are not associated with Sabino 1, though horses with Sabino 1 may have blue eyes from an unrelated genetic factor. Horses with two copies of the Sabino 1 gene - one from each parent - are said to be homozygous for that gene. Homozygous Sabino 1 horses are at least 90% pink-skinned and white-coated at birth. Again, the eyes are not blue; the term "sabino-white" is used to distinguish homozygous SB1/SB1 horses from so-called "dominant white" horses, which need only a single copy of a "white" gene to have a white coat. Without a DNA test, dominant white horses and sabino-white horses are indistinguishable.
Not all "white" horses are sabino-white or dominant white. Combinations of other white spotting patterns, such as tobiano with heterozygous frame overo, can produce a horse, 90% white or more. Cremello horses are superficially similar to sabino-whites, however cremellos have blue eyes, rosy-pink skin and a cream-colored rather than white coat. Gray horses have a white hair coat at maturity but unless they happen to carry dilution, white, or SB1 genes, they do not have pink skin and are not white at birth; the Sabino 1 locus is at the KIT gene. Sabino 1 is an incomplete dominant trait. Both Sabino 1 and the many known forms of dominant white spotting in horses involve the same gene, but they are distinctly labeled. "Dominant white spotting" includes many different phenotypes and genes, while "Sabino 1" is reserved by geneticists for the gene that results in an all-white phenotype in the homozygous state. The alleles, or "versions", of Sabino 1 were designated SB1 and sb1; the gene in the equine wildtype is recessive and the SB1 mutation is dominant.
Sb1/sb1 homozygous recessive, wildtype. The horse will not have true Sabino 1 traits, but may still have white markings due to other factors. SB1/sb1 heterozygous, sabino; the horse wil
The Boulonnais known as the "White Marble Horse", is a draft horse breed. It is known for its large but elegant appearance and is gray, although chestnut and black are allowed by the French breed registry. There were several sub-types, but they were crossbred until only one is seen today; the breed's origins trace to a period before the Crusades and, during the 17th century, Spanish Barb and Andalusian blood were added to create the modern type. During the early 1900s, the Boulonnais were imported in large numbers to the United States and were quite popular in France; the breed nearly became extinct following World War II, but rebounded in France in the 1970s as a popular breed for horse meat. Breed numbers remain low. Studies as early as 1983 indicated a danger of inbreeding within the Boulonnais population, a 2009 report suggested that the breed should be a priority for conservation within France; the smallest type of Boulonnais was used to pull carts full of fresh fish from Boulogne to Paris, while the larger varieties performed heavy draft work, both on farms and in the cities.
The Boulonnais was crossbred to create and refine several other draft breeds. The Boulonnais today stands from 14.3 to 16.3 hands or more. It has a elegant head with a broad forehead and a short, muscular neck. Members of the breed have rounded rib cages and sloping shoulders; the legs are short but robust and strong. Unlike other draft breeds such as the Shire or Clydesdale, it has no heavy feathering on its lower legs; the breed is branded with a small anchor mark on the left side of the neck. Due to the many additions of Oriental blood, the Boulonnais has an elegant appearance, not seen in heavy draft breeds and it has been called "Europe's noblest draft horse"; the fineness of the skin and delicate appearance of the veins has allowed the horse to be described as looking "like polished marble", leading to its "White Marble Horse" nickname. In 1778, the French National Stud performed an initial survey of the breed and found that most were black or dark bay. During the 1800s, gray horses began to appear, it was the predominating color by the end of the century.
Gray became a popular color during this time due to the use of the horses to haul fish at night – gray horses were more visible in the dark, therefore more valuable. In the years of the 20th century, breeders again began to prefer darker colors such as bay and chestnut. Today, chestnut and black are the only colors allowed by the French breed registry, with the vast majority of horses being gray – a popular phrase says that the horses have coats "the color of the clouds from the coast". There were several types of Boulonnais; the Petit Boulonnais, Mareyeuse or Mareyeur was used in the rapid transport of cartloads of fresh fish from the Pas-de-Calais to Paris. The Picard draft came from the Picardy region, was called the "horse of the bad land", in comparison to the Cauchoix horse from the Pays de Caux area, called the "horse of the good land"; the "grand Boulonnais", which stood 15.3 to 16.3 hands high and weighed 1,430 to 1,650 pounds, was bred in the 19th century for farm work in the sugar beet fields.
All of these types were bred together to create the modern Boulonnais horse. One theory states that the origins of the Boulonnais breed emerged from the crossbreeding of native French mares and stallions brought by the Numidian army in 55–54 BC. However, many equine scholars are skeptical of this theory, state that, whatever the early origins, the selective breeding and local climate and soil types had a greater influence on the breed than any early Oriental blood. During the Crusades, two breeders, Comte de Boulogne, Robert, Comte d'Artois, wanted to create a fast and strong warhorse for knights to ride in battle, they crossed the existing heavy French stallions with German Mecklenberg mares, similar to modern-day Hanoverians. During the 17th-century Spanish occupation of Flanders, a mixture of Spanish Barb and Andalusian blood was added to the breed, to create the modern Boulonnais. By the 17th century, horse dealers were coming into the Boulonnais district from Picardy and Upper Normandy to buy local horses, which enjoyed a good reputation among breeders.
From the late 18th through the mid-19th century, the Boulonnais spread across Europe. Beginning in the 1830s, it was proposed to cross the Arabian with the Boulonnais to create a new type of cavalry horse, in the 1860s, calls were put forth to add Thoroughbred blood for the same reason. However, breeders rejected these calls, stating that using the breed to create cavalry horses would make them poorer draft horses. Breed societies discouraged crosses between the Boulonnais and the Brabant. In June 1886, a studbook was created for the breed in France, placed under the jurisdiction of the Syndicat Hippique Boulonnais in 1902. During the early 20th century, the Boulonnais was imported into the United States in large numbers, where it was registered along with other French heavy horse breeds as the "French draft horse". Breed members in the United States were registered with the Anglo-Norman Horse Association (or Nation
American Quarter Horse
The American Quarter Horse, or Quarter Horse, is an American breed of horse that excels at sprinting short distances. Its name came from its ability to outdistance other horse breeds in races of less; the American Quarter Horse is the most popular breed in the United States today, the American Quarter Horse Association is the largest breed registry in the world, with 3 million living American Quarter Horses registered in 2014. The American Quarter Horse is well known both as a race horse and for its performance in rodeos, horse shows and as a working ranch horse; the compact body of the American Quarter Horse is well-suited to the intricate and speedy maneuvers required in reining, working cow horse, barrel racing, calf roping, other western riding events those involving live cattle. The American Quarter Horse is shown in English disciplines and many other equestrian activities.. In the 17th century, colonists on the eastern seaboard of what today is the United States began to cross imported English Thoroughbred horses with assorted "native" horses such as the Chickasaw horse, a breed developed by Native American people from horses descended from Spain, developed from Iberian and Barb stock brought to what is now the Southeastern United States by the Conquistadors.
One of the most famous of these early imports was Janus, a Thoroughbred, the grandson of the Godolphin Arabian. He was foaled in 1746, imported to colonial Virginia in 1756; the influence of Thoroughbreds like Janus contributed genes crucial to the development of the colonial "Quarter Horse". The breed is sometimes referred to as the "Famous American Quarter Running Horse"; the resulting horse was small and quick, was used as a work horse during the week and a race horse on the weekends. As flat racing became popular with the colonists, the Quarter Horse gained more popularity as a sprinter over courses that, by necessity, were shorter than the classic racecourses of England, were no more than a straight stretch of road or flat piece of open land; when matched against a Thoroughbred, local sprinters won. As the Thoroughbred breed became established in America, many colonial Quarter Horses were included in the original American stud books, starting a long association between the Thoroughbred breed and what would become known as the "Quarter Horse", named after the 1⁄4 mile race distance at which it excelled.
With some individuals being clocked at up to 55 mph. In the 19th century, pioneers heading West needed a willing horse. On the Great Plains, settlers encountered horses that descended from the Spanish stock Hernán Cortés and other Conquistadors had introduced into the viceroyalty of New Spain, which today includes the Southwestern United States and Mexico; these horses of the west included herds of feral animals known as Mustangs, as well as horses domesticated by Native Americans, including the Comanche and Nez Perce tribes. As the colonial Quarter Horse was crossed with these western horses, the pioneers found that the new crossbred had innate "cow sense", a natural instinct for working with cattle, making it popular with cattlemen on ranches. Early foundation sires of Quarter horse type included Steel Dust, foaled 1843; the main duty of the ranch horse in the American West was working cattle. After the invention of the automobile, horses were still irreplaceable for handling livestock on the range.
Thus, major Texas cattle ranches, such as the King Ranch, the 6666 Ranch, the Waggoner Ranch played a significant role in the development of the modern Quarter Horse. The skills needed by cowboys and their horses became the foundation of the rodeo, a contest which began with informal competition between cowboys and expanded to become a major competitive event throughout the west. To this day, the Quarter Horse dominates the sport both in speed events and in competition that emphasizes the handling of live cattle. However, sprint races were popular weekend entertainment and racing became a source of economic gain for breeders as well; as a result, more Thoroughbred blood was added back into the developing American Quarter Horse breed. The American Quarter Horse benefitted from the addition of Arabian and Standardbred bloodlines. In 1940, the American Quarter Horse Association was formed by a group of horsemen and ranchers from the southwestern United States dedicated to preserving the pedigrees of their ranch horses.
The horse honored with the first registration number, P-1, was Wimpy, a descendant of the King Ranch foundation sire Old Sorrel. Other sires alive at the founding of the AQHA were given the earliest registration numbers Joe Reed P-3, Chief P-5, Oklahoma Star P-6, Cowboy P-12, Waggoner's Rainy Day P-13; the Thoroughbred race horse Three Bars, alive in the early years of the AQHA, is recognized by the American Quarter Horse Hall of Fame as one of the significant foundation sires for the Quarter Horse breed. Other significant Thoroughbred sires seen in early AQHA pedigrees include Rocket Bar, Top Deck and Depth Charge. Since the American Quarter Horse formally established itself as a breed, the AQHA stud book has remained open to additional Thoroughbred blood via a performance standard. An "Appendix" American Quarter Horse is a first generation cross between a registered Thoroughbred and an
A mare is an adult female horse or other equine. In most cases, a mare is a female horse over the age of three, a filly is a female horse three and younger. In Thoroughbred horse racing, a mare is defined as a female horse more than four years old; the word can be used for other female equine animals mules and zebras, but a female donkey is called a "jenny". A broodmare is a mare used for breeding. A horse's female parent is known as its dam. An uncastrated adult male horse is called a castrated male is a gelding; the term "horse" is used to designate only a male horse. Mares carry their young for 11 months from conception to birth. Just one young is born; when a domesticated mare foals, she nurses the foal for at least four to six months before it is weaned, though mares in the wild may allow a foal to nurse for up to a year. The estrous cycle known as "season" or "heat" of a mare occurs every 19–22 days and occurs from early spring into autumn; as the days shorten, most mares enter an anestrus period during the winter and thus do not cycle in this period.
The reproductive cycle in a mare is controlled by the photoperiod, the cycle first triggered when the days begin to lengthen. As the days shorten, the mare returns to the anestrus period. Anestrus prevents the mare from conceiving in the winter months, as that would result in her foaling during the harshest part of the year, a time when it would be most difficult for the foal to survive. However, for most competitive purposes, foals are given an official "birthday" of January 1, many breeders want foals to be born as early in the year as possible. Therefore, many breeding farms begin to put mares "under lights" in late winter in order to bring them out of anestrus early and allow conception to occur in February or March. One exception to this general rule is the field of endurance riding, which requires horses to be 60 true calendar months old before competing at longer distances. Fillies are sexually mature by age two and are sometimes bred at that age, but should not be bred until they themselves have stopped growing by age four or five.
A healthy, well-managed mare can produce a foal every year into her twenties, though not all breeders will breed a mare every year. In addition, many mares are kept for riding and so are not bred annually, as a mare in late pregnancy or nursing a foal is not able to perform at as athletic a standard as one, neither pregnant nor lactating. In addition, some mares become anxious when separated from their foals temporarily, thus are difficult to manage under saddle until their foals are weaned. Mares are considered easier to handle than stallions. However, geldings have little to no hormone-driven behavior patterns at all, thus sometimes they are preferred to both mares and stallions. Mares have a notorious, if undeserved, reputation for being "marish," meaning that they can be cranky or unwilling when they come into season. While a few mares may be somewhat more distractible or irritable when in heat, they are far less distracted than a stallion at any time. Solid training minimizes hormonal behavior.
For competitive purposes, mares are sometimes placed on hormone therapies, such as the drug Regumate, to help control hormonally based behavior. Some riders use various herbal remedies, most of which have not been extensively tested for effectiveness. In relation to maternal behaviour, the formation of the bond between a mare and her foal "occurs during the first few hours post-partum, but that of the foal to the mare takes place over a period of days". Mares and geldings can be pastured together. However, mares may be a bit more territorial than geldings though they are far less territorial than stallions. Sex-segregating herds may make for less infighting if kept in close quarters. However, studies have shown that when a "lead mare" or "boss mare" is in charge of a herd, all remaining animals rest for longer periods and seem more at ease than do those in herds led by a gelding. In wild herds, a "boss mare" or "lead mare" leads the band to grazing, to water, away from danger, she drinks first, decides when the herd will move and to where.
The herd stallion brings up the rear and acts as a defender of the herd against predators and other stallions. Mares are used in every equestrian sport and compete with stallions and geldings in most events, though some competitions may offer classes open only to one sex of horse or another in breeding or "in-hand" conformation classes. In horse racing and fillies have their own races and only a small percentage compete against male horses. However, a few fillies and mares have won classic horse races against colts, including the Kentucky Derby, the Preakness Stakes, the Belmont Stakes, the Melbourne Cup and the Breeders' Cup Classic. Mares are used as dairy animals in some cultures by the nomads and nomadic peoples of Central Asia. Fermented mare's milk, known as kumis, is the national drink of Kyrgyzstan; some mares of draft horse breeding, are kept in North America for the production of their urine. Pregnant mares' urine is the source of the active ingredient in the hormonal drug Premarin.
Until the invention of castration and later where there was less cultural acceptance of the practice, mares were less difficult to manage than stallions and thus preferred for most ordinary work. The Bedouin nomads of the Arabian peninsula preferred mares on their raids, because stallions would nic
Dominance in genetics is a relationship between alleles of one gene, in which the effect on phenotype of one allele masks the contribution of a second allele at the same locus. The first allele is dominant and the second allele is recessive. For genes on an autosome, the alleles and their associated traits are autosomal dominant or autosomal recessive. Dominance is a key concept in Mendelian inheritance and classical genetics; the dominant allele codes for a functional protein whereas the recessive allele does not. A classic example of dominance is the inheritance of seed shape in peas. Peas associated with allele r. In this case, three combinations of alleles are possible: RR, Rr, rr; the RR individuals have round peas and the rr individuals have wrinkled peas. In Rr individuals the R allele masks the presence of the r allele, so these individuals have round peas. Thus, allele R is dominant to allele r, allele r is recessive to allele R; this use of upper case letters for dominant alleles and lower case ones for recessive alleles is a followed convention.
More where a gene exists in two allelic versions, three combinations of alleles are possible: AA, Aa, aa. If AA and aa individuals show different forms of some trait, Aa individuals show the same phenotype as AA individuals allele A is said to dominate, be dominant to or show dominance to allele a, a is said to be recessive to A. Dominance is not inherent to either its phenotype, it is a relationship between two alleles of their associated phenotypes. An allele may be dominant for a particular aspect of phenotype but not for other aspects influenced by the same gene. Dominance differs from epistasis, a relationship in which an allele of one gene affects the expression of another allele at a different gene; the concept of dominance was introduced by Gregor Johann Mendel. Though Mendel, "The Father of Genetics", first used the term in the 1860s, it was not known until the early twentieth century. Mendel observed that, for a variety of traits of garden peas having to do with the appearance of seeds, seed pods, plants, there were two discrete phenotypes, such as round versus wrinkled seeds, yellow versus green seeds, red versus white flowers or tall versus short plants.
When bred separately, the plants always produced generation after generation. However, when lines with different phenotypes were crossed and only one of the parental phenotypes showed up in the offspring. However, when these hybrid plants were crossed, the offspring plants showed the two original phenotypes, in a characteristic 3:1 ratio, the more common phenotype being that of the parental hybrid plants. Mendel reasoned that each parent in the first cross was a homozygote for different alleles, that each contributed one allele to the offspring, with the result that all of these hybrids were heterozygotes, that one of the two alleles in the hybrid cross dominated expression of the other: A masked a; the final cross between two heterozygotes would produce AA, Aa, aa offspring in a 1:2:1 genotype ratio with the first two classes showing the phenotype, the last showing the phenotype, thereby producing the 3:1 phenotype ratio. Mendel did not use the terms gene, phenotype, genotype and heterozygote, all of which were introduced later.
He did introduce the notation of capital and lowercase letters for dominant and recessive alleles still in use today. Most animals and some plants have paired chromosomes, are described as diploid, they have two versions of each chromosome, one contributed by the mother's ovum, the other by the father's sperm, known as gametes, described as haploid, created through meiosis. These gametes fuse during fertilization during sexual reproduction, into a new single cell zygote, which divides multiple times, resulting in a new organism with the same number of pairs of chromosomes in each cell as its parents; each chromosome of a matching pair is structurally similar to the other, has a similar DNA sequence. The DNA in each chromosome functions as a series of discrete genes that influence various traits. Thus, each gene has a corresponding homologue, which may exist in different versions called alleles; the alleles at the same locus on the two homologous chromosomes may be different. The blood type of a human is determined by a gene that creates an A, B, AB or O blood type and is located in the long arm of chromosome nine.
There are three different alleles that could be present at this locus, but only two can be present in any individual, one inherited from their mother and one from their father. If two alleles of a given gene are identical, the organism is called a homozygote and is said to be homozygous with respect to that gene; the genetic makeup of an organism, either at a single locus or over all its genes collectively, is called its genotype. The genotype of an organism directly and indirectly affects its molecular and other traits, which individually or collectively are called its phenotype. At heterozygous gene loci, the two alleles interact to produce the phenotype. In complete dominance, the effect of one allele in a heterozygous genotype masks the effect of the other; the allele that mas
The Appaloosa is an American horse breed best known for its colorful spotted coat pattern. There is a wide range of body types within the breed, stemming from the influence of multiple breeds of horses throughout its history; each horse's color pattern is genetically the result of various spotting patterns overlaid on top of one of several recognized base coat colors. The color pattern of the Appaloosa is of interest to those who study equine coat color genetics, as it and several other physical characteristics are linked to the leopard complex mutation. Appaloosas are prone to congenital stationary night blindness. Artwork depicting prehistoric horses with leopard spotting exists in prehistoric cave paintings in Europe. Images of domesticated horses with leopard spotting patterns appeared in artwork from Ancient Greece and Han dynasty China through the early modern period. In North America, the Nez Perce people of what today is the United States Pacific Northwest developed the original American breed.
Settlers once referred to these spotted horses as the "Palouse horse" after the Palouse River, which ran through the heart of Nez Perce country. The name evolved into "Appaloosa"; the Nez Perce lost most of their horses after the Nez Perce War in 1877, the breed fell into decline for several decades. A small number of dedicated breeders preserved the Appaloosa as a distinct breed until the Appaloosa Horse Club was formed as the breed registry in 1938; the modern breed maintains bloodlines tracing to the foundation bloodstock of the registry. Today, the Appaloosa is one of the most popular breeds in the United States, it is best known as a stock horse used in a number of western riding disciplines, but is a versatile breed with representatives seen in many other types of equestrian activity. Appaloosas have been used in many movies. Appaloosa bloodlines have influenced other horse breeds, including the Pony of the Americas, the Nez Perce Horse, several gaited horse breeds; the Appaloosa is best known for its distinctive, leopard complex-spotted coat, preferred in the breed.
Spotting occurs in several overlay patterns on one of several recognized base coat colors. There are three other distinctive, "core" characteristics: mottled skin, striped hooves, eyes with a white sclera. Skin mottling is seen around the muzzle, eyes and genitalia. Striped hooves are a common trait, quite noticeable on Appaloosas, but not unique to the breed; the sclera is the part of the eye surrounding the iris. Because the occasional individual is born with little or no visible spotting pattern, the ApHC allows "regular" registration of horses with mottled skin plus at least one of the other core characteristics. Horses with two ApHC parents but no "identifiable Appaloosa characteristics" are registered as "non-characteristic," a limited special registration status. There is a wide range of body types in the Appaloosa, in part because the leopard complex characteristics are its primary identifying factors, because several different horse breeds influenced its development; the weight range varies from 950 to 1,250 pounds, heights from 14 to 16 hands.
However, the ApHC does not allow draft breeding. The original "old time" or "old type" Appaloosa was a narrow-bodied, rangy horse; the body style reflected a mix that started with the traditional Spanish horses common on the plains of America before 1700. 18th-century European bloodlines were added those of the "pied" horses popular in that period and shipped en masse to the Americas once the color had become unfashionable in Europe. These horses were similar to a tall, slim Thoroughbred-Andalusian type of horse popular in Bourbon-era Spain; the original Appaloosa tended to have a convex facial profile that resembled that of the warmblood-Jennet crosses first developed in the 16th century during the reign of Charles V. The old-type Appaloosa was modified by the addition of draft horse blood after the 1877 defeat of the Nez Perce, when U. S. Government policy forced the Indians to become farmers and provided them with draft horse mares to breed to existing stallions; the original Appaloosas had a sparse mane and tail, but, not a primary characteristic, as many early Appaloosas did have full manes and tails.
There is a possible genetic link between the leopard complex and sparse mane and tail growth, although the precise relationship is unknown. After the formation of the Appaloosa Horse Club in 1938, a more modern type of horse was developed after the addition of American Quarter Horse and Arabian bloodlines; the addition of Quarter Horse lines produced Appaloosas that performed better in sprint racing and in halter competition. Many cutting and reining horses resulted from old-type Appaloosas crossed on Arabian bloodlines via the Appaloosa foundation stallion Red Eagle. An infusion of Thoroughbred blood was added during the 1970s to produce horses more suited for racing. Many current breeders attempt to breed away from the sparse, "rat tail" trait, therefore modern Appaloosas have fuller manes and tails; the coat color of an Appaloosa is a combination of a base color with an overlaid spotting pattern. The base colors r