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The horse (''Equus ferus caballus'') is a
domesticated Domestication is a sustained multi-generational relationship in which humans assume a significant degree of control over the reproduction and care of another group of organisms to secure a more predictable supply of resources from that group. A ...
, one-toed, hoofed mammal. It belongs to the taxonomic family
Equidae Equidae (sometimes known as the horse family) is the taxonomic family of horses and related animals, including the extant horses, asses, and zebras, and many other species known only from fossils. All extant species are in the genus '' Equus'', ...
and is one of two
extant Extant is the opposite of the word extinct. It may refer to: * Extant hereditary titles * Extant literature, surviving literature, such as ''Beowulf'', the oldest extant manuscript written in English * Extant taxon, a taxon which is not extinct, ...
subspecies In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (morphology), but that can successfully interbreed. Not all species ...
of ''Equus ferus''. The horse has
evolved Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation ...
over the past 45 to 55 million years from a small multi-toed creature, ''
Eohippus ''Eohippus'' is an extinct genus of small equid ungulates. The only species is ''E. angustidens'', which was long considered a species of ''Hyracotherium''. Its remains have been identified in North America and date to the Early Eocene (Ypresian ...
'', into the large, single-toed animal of today. Humans began domesticating horses around 4000 BCE, and their
domestication Domestication is a sustained multi-generational relationship in which humans assume a significant degree of control over the reproduction and care of another group of organisms to secure a more predictable supply of resources from that group. ...
is believed to have been widespread by 3000 BCE. Horses in the subspecies ''caballus'' are domesticated, although some domesticated populations live in the wild as
feral horse A feral horse is a free-roaming horse of domesticated stock. As such, a feral horse is not a wild animal in the sense of an animal without domesticated ancestors. However, some populations of feral horses are managed as wildlife, and these ...
s. These feral populations are not true
wild horse The wild horse (''Equus ferus'') is a species of the genus ''Equus'', which includes as subspecies the modern domesticated horse (''Equus ferus caballus'') as well as the endangered Przewalski's horse (''Equus ferus przewalskii''). The Europea ...
s, as this term is used to describe horses that have never been domesticated. There is an extensive, specialized vocabulary used to describe equine-related concepts, covering everything from
anatomy Anatomy () is the branch of biology concerned with the study of the structure of organisms and their parts. Anatomy is a branch of natural science that deals with the structural organization of living things. It is an old science, having its ...
to life stages, size,
colors Color (American English) or colour (British English) is the visual perceptual property deriving from the spectrum of light interacting with the photoreceptor cells of the eyes. Color categories and physical specifications of color are associa ...
, markings,
breeds A breed is a specific group of domestic animals having homogeneous appearance (phenotype), homogeneous behavior, and/or other characteristics that distinguish it from other organisms of the same species. In literature, there exist several slight ...
,
locomotion Locomotion means the act or ability of something to transport or move itself from place to place. Locomotion may refer to: Motion * Motion (physics) * Robot locomotion, of man-made devices By environment * Aquatic locomotion * Flight * Locomo ...
, and behavior. Horses are adapted to run, allowing them to quickly escape predators, and possess an excellent
sense of balance The sense of balance or equilibrioception is the perception of balance and spatial orientation. It helps prevent humans and nonhuman animals from falling over when standing or moving. Equilibrioception is the result of a number of sensory syste ...
and a strong
fight-or-flight response The fight-or-flight or the fight-flight-or-freeze response (also called hyperarousal or the acute stress response) is a physiological reaction that occurs in response to a perceived harmful event, attack, or threat to survival. It was first des ...
. Related to this need to flee from predators in the wild is an unusual trait: horses are able to sleep both standing up and lying down, with younger horses tending to sleep significantly more than adults. Female horses, called
mare A mare is an adult female horse or other equine. In most cases, a mare is a female horse over the age of three, and a filly is a female horse three and younger. In Thoroughbred horse racing, a mare is defined as a female horse more than four ...
s, carry their young for approximately 11 months and a young horse, called a
foal A foal is an equine up to one year old; this term is used mainly for horses, but can be used for donkeys. More specific terms are colt for a male foal and filly for a female foal, and are used until the horse is three or four. When the foal i ...
, can stand and run shortly following birth. Most domesticated horses begin training under a
saddle The saddle is a supportive structure for a rider of an animal, fastened to an animal's back by a girth. The most common type is equestrian. However, specialized saddles have been created for oxen, camels and other animals. It is not kno ...
or in a
harness A harness is a looped restraint or support. Specifically, it may refer to one of the following harness types: * Bondage harness * Child harness * Climbing harness * Dog harness * Pet harness * Five-point harness * Horse harness * Parrot harness * ...
between the ages of two and four. They reach full adult development by age five, and have an average lifespan of between 25 and 30 years. Horse breeds are loosely divided into three categories based on general temperament: spirited "hot bloods" with speed and endurance; "cold bloods", such as
draft horse A draft horse (US), draught horse (UK) or dray horse (from the Old English ''dragan'' meaning "to draw or haul"; compare Dutch ''dragen'' and German ''tragen'' meaning "to carry" and Danish ''drage'' meaning "to draw" or "to fare"), less often ...
s and some
ponies A pony is a type of small horse ('' Equus ferus caballus''). Depending on the context, a pony may be a horse that is under an approximate or exact height at the withers, or a small horse with a specific conformation and temperament. Compared ...
, suitable for slow, heavy work; and "
warmblood Warmbloods are a group of middle-weight horse types and breeds primarily originating in Europe and registered with organizations that are characterized by open studbook policy, studbook selection, and the aim of breeding for equestrian sport. ...
s", developed from crosses between hot bloods and cold bloods, often focusing on creating breeds for specific riding purposes, particularly in Europe. There are more than 300 breeds of horse in the world today, developed for many different uses. Horses and humans interact in a wide variety of sport competitions and non-competitive recreational pursuits as well as in working activities such as police work,
agriculture Agriculture or farming is the practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled people to ...
, entertainment, and
therapy A therapy or medical treatment (often abbreviated tx, Tx, or Tx) is the attempted remediation of a health problem, usually following a medical diagnosis. As a rule, each therapy has indications and contraindications. There are many different ...
. Horses were historically used in warfare, from which a wide variety of riding and
driving Driving is the controlled operation and movement of a vehicle, including cars, motorcycles, trucks, buses, and bicycles. Permission to drive on public highways is granted based on a set of conditions being met and drivers are required to fol ...
techniques developed, using many different styles of
equipment Equipment most commonly refers to a set of tools or other objects commonly used to achieve a particular objective. Different job Work or labor (or labour in British English) is intentional activity people perform to support the needs and ...
and methods of control. Many products are derived from horses, including
meat Meat is animal flesh that is eaten as food. Humans have hunted, farmed, and scavenged animals for meat since prehistoric times. The establishment of settlements in the Neolithic Revolution allowed the domestication of animals such as chic ...
,
milk Milk is a white liquid food produced by the mammary glands of mammals. It is the primary source of nutrition for young mammals (including breastfed human infants) before they are able to digestion, digest solid food. Immune factors and immune ...
, hide,
hair Hair is a protein filament that grows from follicles found in the dermis. Hair is one of the defining characteristics of mammals. The human body, apart from areas of glabrous skin, is covered in follicles which produce thick terminal and f ...
, bone, and pharmaceuticals extracted from the urine of pregnant mares. Humans provide domesticated horses with food, water, and shelter as well as attention from specialists such as
veterinarian A veterinarian (vet), also known as a veterinary surgeon or veterinary physician, is a medical professional who practices veterinary medicine. They manage a wide range of health conditions and injuries in non-human animals. Along with this, vet ...
s and
farrier A farrier is a specialist in equine hoof care, including the trimming and balancing of horses' hooves and the placing of shoes on their hooves, if necessary. A farrier combines some blacksmith's skills (fabricating, adapting, and adjus ...
s.


Biology

Specific terms and specialized language are used to describe
equine anatomy Equine anatomy encompasses the gross and microscopic anatomy of horses, ponies and other equids, including donkeys, mules and zebras. While all anatomical features of equids are described in the same terms as for other animals by the Internatio ...
, different life stages, and colors and breeds.


Lifespan and life stages

Depending on breed,
management Management (or managing) is the administration of an organization, whether it is a business, a nonprofit organization, or a government body. It is the art and science of managing resources of the business. Management includes the activities o ...
and environment, the modern domestic horse has a life expectancy of 25 to 30 years. Uncommonly, a few animals live into their 40s and, occasionally, beyond. The oldest verifiable record was "
Old Billy Old Billy (also called Billy or Ol' Billy) was the longest-living horse on record. Old Billy was verified to be 62 at his death. Born in Woolston, Cheshire, England in 1760, Billy adventured and became a barge horse that pulled barges up and down ...
", a 19th-century horse that lived to the age of 62. In modern times, Sugar Puff, who had been listed in ''
Guinness World Records ''Guinness World Records'', known from its inception in 1955 until 1999 as ''The Guinness Book of Records'' and in previous United States editions as ''The Guinness Book of World Records'', is a reference book published annually, listing world ...
'' as the world's oldest living pony, died in 2007 at age 56. Regardless of a horse or pony's actual birth date, for most competition purposes a year is added to its age each January 1 of each year in the Northern Hemisphere and each August 1 in the Southern Hemisphere. The exception is in
endurance riding Endurance riding is an equestrian sport based on controlled long-distance races. It is one of the international competitions recognized by the FEI. There are endurance rides worldwide. Endurance rides can be any distance, though they are rare ...
, where the minimum age to compete is based on the animal's actual calendar age. The following terminology is used to describe horses of various ages: ;
Foal A foal is an equine up to one year old; this term is used mainly for horses, but can be used for donkeys. More specific terms are colt for a male foal and filly for a female foal, and are used until the horse is three or four. When the foal i ...
: A horse of either sex less than one year old. A nursing foal is sometimes called a ''suckling'', and a foal that has been weaned is called a ''weanling''. Ensminger, p. 418 Most domesticated foals are weaned at five to seven months of age, although foals can be weaned at four months with no adverse physical effects. ;
Yearling Yearling may refer to: *Yearling (horse), a horse between one and two years old *''The Yearling ''The Yearling'' is a novel by American writer Marjorie Kinnan Rawlings, published in March 1938. It was the main selection of the Book of the Mo ...
: A horse of either sex that is between one and two years old. ;
Colt Colt(s) or COLT may refer to: *Colt (horse), an intact (uncastrated) male horse under four years of age People * Colt (given name) *Colt (surname) Places *Colt, Arkansas, United States *Colt, Louisiana, an unincorporated community, United States ...
: A male horse under the age of four. A common terminology error is to call any young horse a "colt", when the term actually only refers to young male horses. ;
Filly A filly is a female horse that is too young to be called a mare. There are two specific definitions in use: *In most cases, a ''filly'' is a female horse under four years old. *In some nations, such as the United Kingdom and the United States, t ...
: A female horse under the age of four. ;
Mare A mare is an adult female horse or other equine. In most cases, a mare is a female horse over the age of three, and a filly is a female horse three and younger. In Thoroughbred horse racing, a mare is defined as a female horse more than four ...
: A female horse four years old and older. ;
Stallion A stallion is a male horse that has not been gelded (castrated). Stallions follow the conformation and phenotype of their breed, but within that standard, the presence of hormones such as testosterone may give stallions a thicker, "cresty" nec ...
: A non-castrated male horse four years old and older. The term "horse" is sometimes used colloquially to refer specifically to a stallion. Ensminger, p. 420 ;
Gelding A gelding is a castrated male horse or other equine, such as a pony, donkey or a mule. Castration, as well as the elimination of hormonally driven behavior associated with a stallion, allows a male equine to be calmer and better-behaved, makin ...
: A
castrated Castration is any action, surgical, chemical, or otherwise, by which an individual loses use of the testicles: the male gonad. Surgical castration is bilateral orchiectomy (excision of both testicles), while chemical castration uses pharmaceut ...
male horse of any age. In
horse racing Horse racing is an equestrian performance sport, typically involving two or more horses ridden by jockeys (or sometimes driven without riders) over a set distance for competition. It is one of the most ancient of all sports, as its basic p ...
, these definitions may differ: For example, in the British Isles,
Thoroughbred The Thoroughbred is a horse breed best known for its use in 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 c ...
horse racing defines colts and fillies as less than five years old. However, Australian Thoroughbred racing defines colts and fillies as less than four years old.


Size and measurement

The height of horses is measured at the highest point of the
withers The withers is the ridge between the shoulder blades of an animal, typically a quadruped. In many species, it is the tallest point of the body. In horses and dogs, it is the standard place to measure the animal's height. In contrast, cattle ar ...
, where the neck meets the
back The human back, also called the dorsum, is the large posterior area of the human body, rising from the top of the buttocks to the back of the neck. It is the surface of the body opposite from the chest and the abdomen. The vertebral column runs ...
.
Whitaker Whitaker (also Whittaker) is a surname of English and Scottish origin, meaning the white acre, also spelled "Whittaker" and " Whitacre." Notable people with the surname include: People with the name * The Whitaker iron family - a family important ...
, p. 77
This point is used because it is a stable point of the anatomy, unlike the head or neck, which move up and down in relation to the body of the horse. In English-speaking countries, the height of horses is often stated in units of
hands A hand is a prehensile, multi-fingered appendage located at the end of the forearm or forelimb of primates such as humans, chimpanzees, monkeys, and lemurs. A few other vertebrates such as the koala (which has two opposable thumbs on each " ...
and inches: one hand is equal to . The height is expressed as the number of full hands, followed by a
point Point or points may refer to: Places * Point, Lewis, a peninsula in the Outer Hebrides, Scotland * Point, Texas, a city in Rains County, Texas, United States * Point, the NE tip and a ferry terminal of Lismore, Inner Hebrides, Scotland * Point ...
, then the number of additional inches, and ending with the abbreviation "h" or "hh" (for "hands high"). Thus, a horse described as "15.2 h" is 15 hands plus 2 inches, for a total of in height. Ensminger, p. 51 The size of horses varies by breed, but also is influenced by
nutrition Nutrition is the biochemical and physiological process by which an organism uses food to support its life. It provides organisms with nutrients, which can be metabolized to create energy and chemical structures. Failure to obtain sufficient n ...
. Light-riding horses usually range in height from and can weigh from . Larger-riding horses usually start at about and often are as tall as , weighing from . Heavy or
draft horse A draft horse (US), draught horse (UK) or dray horse (from the Old English ''dragan'' meaning "to draw or haul"; compare Dutch ''dragen'' and German ''tragen'' meaning "to carry" and Danish ''drage'' meaning "to draw" or "to fare"), less often ...
s are usually at least high and can be as tall as high. They can weigh from about . The largest horse in recorded history was probably a
Shire horse The Shire is a British breed of draught horse. It is usually black, bay, or grey. It is a tall breed, and Shires have at various times held world records both for the largest horse and for the tallest horse. The Shire has a great capacity for ...
named
Mammoth A mammoth is any species of the extinct elephantid genus ''Mammuthus'', one of the many genera that make up the order of trunked mammals called proboscideans. The various species of mammoth were commonly equipped with long, curved tusks and, ...
, who was born in 1848. He stood high and his peak weight was estimated at .
Whitaker Whitaker (also Whittaker) is a surname of English and Scottish origin, meaning the white acre, also spelled "Whittaker" and " Whitacre." Notable people with the surname include: People with the name * The Whitaker iron family - a family important ...
, p. 60
The record holder for the smallest horse ever is
Thumbelina Thumbelina (; da, Tommelise) is a literary fairy tale written by Danish author Hans Christian Andersen first published by C. A. Reitzel on 16 December 1835 in Copenhagen, Denmark, with "The Naughty Boy" and "The Travelling Companion" in t ...
, a fully mature
miniature horse A miniature horse is a breed or type of horse characterised by its small size. Usually it has been bred to display in miniature the physical characteristics of a full-sized horse, but to be little over in height, or even less. Although such hor ...
affected by
dwarfism Dwarfism is a condition wherein an organism is exceptionally small, and mostly occurs in the animal kingdom. In humans, it is sometimes defined as an adult height of less than , regardless of sex; the average adult height among people with dw ...
. She was tall and weighed .


Ponies

Ponies A pony is a type of small horse ('' Equus ferus caballus''). Depending on the context, a pony may be a horse that is under an approximate or exact height at the withers, or a small horse with a specific conformation and temperament. Compared ...
are
taxonomically In biology, taxonomy () is the scientific study of naming, defining ( circumscribing) and classifying groups of biological organisms based on shared characteristics. Organisms are grouped into taxa (singular: taxon) and these groups are given ...
the same animals as horses. The distinction between a horse and pony is commonly drawn on the basis of height, especially for competition purposes. However, height alone is not dispositive; the difference between horses and ponies may also include aspects of
phenotype In genetics, the phenotype () is the set of observable characteristics or traits of an organism. The term covers the organism's morphology or physical form and structure, its developmental processes, its biochemical and physiological proper ...
, including conformation and temperament. The traditional standard for height of a horse or a pony at maturity is . An animal or over is usually considered to be a horse and one less than a pony, but there are many exceptions to the traditional standard. In Australia, ponies are considered to be those under . For competition in the
Western Western may refer to: Places *Western, Nebraska, a village in the US *Western, New York, a town in the US *Western Creek, Tasmania, a locality in Australia *Western Junction, Tasmania, a locality in Australia *Western world, countries that id ...
division of the United States Equestrian Federation, the cutoff is . The
International Federation for Equestrian Sports The International Federation for Equestrian Sports (, FEI) is the international governing body of equestrian sports. The FEI headquarters are in Lausanne, Switzerland. An FEI code of conduct protects the welfare of the horses from physical abu ...
, the world governing body for horse sport, uses
metric Metric or metrical may refer to: * Metric system, an internationally adopted decimal system of measurement * An adjective indicating relation to measurement in general, or a noun describing a specific type of measurement Mathematics In mathem ...
measurements and defines a pony as being any horse measuring less than at the withers without shoes, which is just over , and , with shoes. Height is not the sole criterion for distinguishing horses from ponies. Breed registries for horses that typically produce individuals both under and over consider all animals of that breed to be horses regardless of their height. Conversely, some pony breeds may have features in common with horses, and individual animals may occasionally mature at over , but are still considered to be ponies. Ponies often exhibit thicker manes, tails, and overall coat. They also have proportionally shorter legs, wider barrels, heavier bone, shorter and thicker necks, and short heads with broad foreheads. They may have calmer temperaments than horses and also a high level of intelligence that may or may not be used to cooperate with human handlers. Small size, by itself, is not an exclusive determinant. For example, the
Shetland pony The Shetland pony is a Scottish breed of pony originating in the Shetland Isles in the north of Scotland. It may stand up to at the withers. It has a heavy coat and short legs, is strong for its size, and is used for riding, driving, and p ...
which averages , is considered a pony. Conversely, breeds such as the
Falabella The Falabella is an Argentine list of horse breeds, breed of small horse. It is among the smallest of horse breeds, with a height at the withers in the range .. History The ancestral stock of the horse of South America descended from horses bro ...
and other
miniature horse A miniature horse is a breed or type of horse characterised by its small size. Usually it has been bred to display in miniature the physical characteristics of a full-sized horse, but to be little over in height, or even less. Although such hor ...
s, which can be no taller than , are classified by their registries as very small horses, not ponies.


Genetics

Horses have 64
chromosome A chromosome is a long DNA molecule with part or all of the genetic material of an organism. In most chromosomes the very long thin DNA fibers are coated with packaging proteins; in eukaryotic cells the most important of these proteins are ...
s. The
horse genome The horse genome was first sequenced in 2006. The Horse Genome Project mapped 2.7 billion DNA base pairs, and released the full map in 2009. The horse genome is larger than the dog genome, but smaller than the human genome or the bovine genome. ...
was
sequenced In genetics and biochemistry, sequencing means to determine the primary structure (sometimes incorrectly called the primary sequence) of an unbranched biopolymer. Sequencing results in a symbolic linear depiction known as a sequence which suc ...
in 2007. It contains 2.7 billion DNA
base pair A base pair (bp) is a fundamental unit of double-stranded nucleic acids consisting of two nucleobases bound to each other by hydrogen bonds. They form the building blocks of the DNA double helix and contribute to the folded structure of both DNA ...
s, which is larger than the
dog genome Genome projects are scientific endeavours that ultimately aim to determine the complete genome sequence of an organism (be it an animal, a plant, a fungus, a bacterium, an archaean, a protist or a virus) and to annotate protein-coding genes and ot ...
, but smaller than the
human genome The human genome is a complete set of nucleic acid sequences for humans, encoded as DNA within the 23 chromosome pairs in cell nuclei and in a small DNA molecule found within individual mitochondria. These are usually treated separately as the n ...
or the
bovine genome The genome of a female Hereford cow was published in 2009. It was sequenced by the Bovine Genome Sequencing and Analysis Consortium, a team of researchers led by the National Institutes of Health and the U.S. Department of Agriculture. It was par ...
. The map is available to researchers.


Colors and markings

Horses exhibit a diverse array of coat colors and distinctive markings, described by a specialized vocabulary. Often, a horse is classified first by its coat color, before breed or sex. Horses of the same color may be distinguished from one another by white markings, which, along with various spotting patterns, are inherited separately from coat color. Many
genes In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ...
that create horse coat colors and patterns have been identified. Current genetic tests can identify at least 13 different
allele An allele (, ; ; modern formation from Greek ἄλλος ''állos'', "other") is a variation of the same sequence of nucleotides at the same place on a long DNA molecule, as described in leading textbooks on genetics and evolution. ::"The chro ...
s influencing coat color, and research continues to discover new genes linked to specific traits. The basic coat colors of
chestnut The chestnuts are the deciduous trees and shrubs in the genus ''Castanea'', in the beech family Fagaceae. They are native to temperate regions of the Northern Hemisphere. The name also refers to the edible nuts they produce. The unrelat ...
and
black Black is a color which results from the absence or complete absorption of visible light. It is an achromatic color, without hue, like white and grey. It is often used symbolically or figuratively to represent darkness. Black and white have o ...
are determined by the
gene In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ...
controlled by the
Melanocortin 1 receptor The melanocortin 1 receptor (MC1R), also known as melanocyte-stimulating hormone receptor (MSHR), melanin-activating peptide receptor, or melanotropin receptor, is a G protein–coupled receptor that binds to a class of pituitary peptide hormones ...
, also known as the "extension gene" or "red factor," as its recessive form is "red" (chestnut) and its dominant form is black. Additional
gene In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ...
s control suppression of black color to
point coloration Point coloration refers to animal coat coloration with a pale body and relatively darker extremities, i.e. the face, ears, feet, tail, and (in males) scrotum. It is most recognized as the coloration of Siamese and related breeds of cat, but can ...
that results in a bay, spotting patterns such as
pinto Pinto is a Portuguese language, Portuguese, Spanish language, Spanish, Sephardi Jews, Jewish (Sephardic), and Italian language, Italian surname. It is a high-frequency surname in all List of countries and territories where Portuguese is an officia ...
or
leopard The leopard (''Panthera pardus'') is one of the five extant species in the genus '' Panthera'', a member of the cat family, Felidae. It occurs in a wide range in sub-Saharan Africa, in some parts of Western and Central Asia, Southern Russia, a ...
, dilution genes such as
palomino Palomino is a genetic color in horses, consisting of a gold coat and white mane and tail; the degree of whiteness can vary from bright white to yellow. Genetically, the palomino color is created by a single allele of a dilution gene called t ...
or
dun A dun is an ancient or medieval fort. In Ireland and Britain it is mainly a kind of hillfort and also a kind of Atlantic roundhouse. Etymology The term comes from Irish language, Irish ''dún'' or Scottish Gaelic ''dùn'' (meaning "fort"), ...
, as well as greying, and all the other factors that create the many possible coat colors found in horses. Horses that have a white coat color are often mislabeled; a horse that looks "white" is usually a middle-aged or older
gray Grey (more common in British English) or gray (more common in American English) is an intermediate color between black and white. It is a neutral or achromatic color, meaning literally that it is "without color", because it can be composed o ...
. Grays are born a darker shade, get lighter as they age, but usually keep black skin underneath their white hair coat (with the exception of pink skin under white markings). The only horses properly called
white White is the lightest color and is achromatic (having no hue). It is the color of objects such as snow, chalk, and milk, and is the opposite of black. White objects fully reflect and scatter all the visible wavelengths of light. White on ...
are born with a predominantly white hair coat and pink skin, a fairly rare occurrence. Different and unrelated genetic factors can produce white coat colors in horses, including several different alleles of
dominant white Dominant white (W) is a group of genetically related coat color alleles on the KIT gene of the horse, best known for producing an all-white coat, but also able to produce various forms of white spotting, as well as bold white markings. Prior ...
and the sabino-1 gene. However, there are no "
albino Albinism is the congenital absence of melanin in an animal or plant resulting in white hair, feathers, scales and skin and pink or blue eyes. Individuals with the condition are referred to as albino. Varied use and interpretation of the term ...
" horses, defined as having both pink skin and red eyes.


Reproduction and development

Gestation Gestation is the period of development during the carrying of an embryo, and later fetus, inside viviparous animals (the embryo develops within the parent). It is typical for mammals, but also occurs for some non-mammals. Mammals during pregna ...
lasts approximately 340 days, with an average range 320–370 days, Ensminger, p. 156 and usually results in one
foal A foal is an equine up to one year old; this term is used mainly for horses, but can be used for donkeys. More specific terms are colt for a male foal and filly for a female foal, and are used until the horse is three or four. When the foal i ...
; twins are rare. Horses are a precocial species, and foals are capable of standing and running within a short time following birth. Foals are usually born in the spring. The
estrous cycle The estrous cycle (, originally ) is the set of recurring physiological changes that are induced by reproductive hormones in most mammalian therian females. Estrous cycles start after sexual maturity in females and are interrupted by anestrous p ...
of a mare occurs roughly every 19–22 days and occurs from early spring into autumn. Most mares enter an ''anestrus'' period during the winter and thus do not cycle in this period. Ensminger, p. 150 Foals are generally
weaned Weaning is the process of gradually introducing an infant human or another mammal to what will be its adult diet while withdrawing the supply of its mother's milk. The process takes place only in mammals, as only mammals produce milk. The infan ...
from their mothers between four and six months of age. Horses, particularly colts, are sometimes physically capable of reproduction at about 18 months, but domesticated horses are rarely allowed to breed before the age of three, especially females. Horses four years old are considered mature, although the skeleton normally continues to develop until the age of six; maturation also depends on the horse's size, breed, sex, and quality of care. Larger horses have larger bones; therefore, not only do the bones take longer to form
bone tissue A bone is a rigid organ that constitutes part of the skeleton in most vertebrate animals. Bones protect the various other organs of the body, produce red and white blood cells, store minerals, provide structure and support for the body, an ...
, but the
epiphyseal plate The epiphyseal plate (or epiphysial plate, physis, or growth plate) is a hyaline cartilage plate in the metaphysis at each end of a long bone. It is the part of a long bone where new bone growth takes place; that is, the whole bone is alive, wi ...
s are larger and take longer to convert from
cartilage Cartilage is a resilient and smooth type of connective tissue. In tetrapods, it covers and protects the ends of long bones at the joints as articular cartilage, and is a structural component of many body parts including the rib cage, the neck an ...
to bone. These plates convert after the other parts of the bones, and are crucial to development. Depending on maturity, breed, and work expected, horses are usually put under saddle and
trained Training is teaching, or developing in oneself or others, any skills and knowledge or fitness that relate to specific useful competencies. Training has specific goals of improving one's capability, capacity, productivity and performance. I ...
to be ridden between the ages of two and four. Although
Thoroughbred The Thoroughbred is a horse breed best known for its use in 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 c ...
race horses Race Horses were a Welsh band based in Cardiff, Wales and originally from Aberystwyth. Formed in 2005 as Radio Luxembourg, they changed their name in 2009 due to possible legal problems with the radio station of the same name. Initially the m ...
are put on the track as young as the age of two in some countries, horses specifically bred for sports such as
dressage Dressage ( or ; a French term, most commonly translated to mean "training") is a form of horse riding performed in exhibition and competition, as well as an art sometimes pursued solely for the sake of mastery. As an equestrian sport defined b ...
are generally not put under saddle until they are three or four years old, because their bones and muscles are not solidly developed. For
endurance riding Endurance riding is an equestrian sport based on controlled long-distance races. It is one of the international competitions recognized by the FEI. There are endurance rides worldwide. Endurance rides can be any distance, though they are rare ...
competition, horses are not deemed mature enough to compete until they are a full 60 calendar months (five years) old.


Anatomy


Skeletal system

The horse skeleton averages 205 bones. A significant difference between the horse skeleton and that of a human is the lack of a
collarbone The clavicle, or collarbone, is a slender, S-shaped long bone approximately 6 inches (15 cm) long that serves as a strut between the shoulder blade and the sternum (breastbone). There are two clavicles, one on the left and one on the right ...
—the horse's
forelimbs A forelimb or front limb is one of the paired articulated appendages (limbs) attached on the cranial (anterior) end of a terrestrial tetrapod vertebrate's torso. With reference to quadrupeds, the term foreleg or front leg is often used instead. ...
are attached to the
spinal column The vertebral column, also known as the backbone or spine, is part of the axial skeleton. The vertebral column is the defining characteristic of a vertebrate in which the notochord (a flexible rod of uniform composition) found in all chordates ...
by a powerful set of muscles, tendons, and ligaments that attach the shoulder blade to the torso. The horse's four legs and hooves are also unique structures. Their leg bones are proportioned differently from those of a human. For example, the body part that is called a horse's "knee" is actually made up of the
carpal bones The carpal bones are the eight small bones that make up the wrist (or carpus) that connects the hand to the forearm. The term "carpus" is derived from the Latin carpus and the Greek καρπός (karpós), meaning "wrist". In human anatomy, th ...
that correspond to the human
wrist In human anatomy, the wrist is variously defined as (1) the Carpal bones, carpus or carpal bones, the complex of eight bones forming the proximal skeletal segment of the hand; "The wrist contains eight bones, roughly aligned in two rows, known ...
. Similarly, the
hock Hock may refer to: Common meanings: * Hock (wine), a type of wine * Hock (anatomy), part of an animal's leg * To leave an item with a pawnbroker People: * Hock (surname) * Richard "Hock" Walsh (1948-1999), Canadian blues singer Other uses: * A t ...
contains bones equivalent to those in the human
ankle The ankle, or the talocrural region, or the jumping bone (informal) is the area where the foot and the leg meet. The ankle includes three joints: the ankle joint proper or talocrural joint, the subtalar joint, and the inferior tibiofibular join ...
and
heel The heel is the prominence at the posterior end of the foot. It is based on the projection of one bone, the calcaneus or heel bone, behind the articulation of the bones of the lower Human leg, leg. Structure To distribute the compressive for ...
. The lower leg bones of a horse correspond to the bones of the human hand or foot, and the
fetlock Fetlock is the common name in horses, large animals, and sometimes dogs for the metacarpophalangeal and metatarsophalangeal joints (MCPJ and MTPJ). Although it somewhat resembles the human ankle in appearance, the joint is homologous to the ba ...
(incorrectly called the "ankle") is actually the proximal
sesamoid bone In anatomy, a sesamoid bone () is a bone embedded within a tendon or a muscle. Its name is derived from the Arabic word for ' sesame seed', indicating the small size of most sesamoids. Often, these bones form in response to strain, or can be pres ...
s between the
cannon A cannon is a large- caliber gun classified as a type of artillery, which usually launches a projectile using explosive chemical propellant. Gunpowder ("black powder") was the primary propellant before the invention of smokeless powder ...
bones (a single equivalent to the human
metacarpal In human anatomy, the metacarpal bones or metacarpus form the intermediate part of the skeletal hand located between the phalanges of the fingers and the carpal bones of the wrist, which forms the connection to the forearm. The metacarpal bones ...
or
metatarsal bones The metatarsal bones, or metatarsus, are a group of five long bones in the foot, located between the tarsal bones of the hind- and mid-foot and the phalanges of the toes. Lacking individual names, the metatarsal bones are numbered from the medi ...
) and the
proximal phalanges The phalanges (singular: ''phalanx'' ) are digital bones in the hands and feet of most vertebrates. In primates, the thumbs and big toes have two phalanges while the other digits have three phalanges. The phalanges are classed as long bones. ...
, located where one finds the "knuckles" of a human. A horse also has no muscles in its legs below the knees and hocks, only skin, hair, bone,
tendon A tendon or sinew is a tough, high-tensile-strength band of dense fibrous connective tissue that connects muscle to bone. It is able to transmit the mechanical forces of muscle contraction to the skeletal system without sacrificing its ability ...
s,
ligament A ligament is the fibrous connective tissue that connects bones to other bones. It is also known as ''articular ligament'', ''articular larua'', ''fibrous ligament'', or ''true ligament''. Other ligaments in the body include the: * Peritoneal li ...
s,
cartilage Cartilage is a resilient and smooth type of connective tissue. In tetrapods, it covers and protects the ends of long bones at the joints as articular cartilage, and is a structural component of many body parts including the rib cage, the neck an ...
, and the assorted specialized tissues that make up the
hoof The hoof (plural: hooves) is the tip of a toe of an ungulate mammal, which is covered and strengthened with a thick and horny keratin covering. Artiodactyls are even-toed ungulates, species whose feet have an even number of digits, yet the rumin ...
. Ensminger, pp. 21–25


Hooves

The critical importance of the feet and legs is summed up by the traditional adage, "no foot, no horse". Ensminger, p. 367 The
horse hoof A horse hoof is the lower extremity of each leg of a horse, the part that makes contact with the ground and carries the weight of the animal. It is both hard and flexible. It is a complex structure surrounding the distal phalanx of the 3rd digit ...
begins with the
distal phalanges The phalanges (singular: ''phalanx'' ) are digital bones in the hands and feet of most vertebrates. In primates, the thumbs and big toes have two phalanges while the other digits have three phalanges. The phalanges are classed as long bones. ...
, the equivalent of the human fingertip or tip of the toe, surrounded by
cartilage Cartilage is a resilient and smooth type of connective tissue. In tetrapods, it covers and protects the ends of long bones at the joints as articular cartilage, and is a structural component of many body parts including the rib cage, the neck an ...
and other specialized, blood-rich soft tissues such as the laminae. The exterior hoof wall and horn of the sole is made of
keratin Keratin () is one of a family of structural fibrous proteins also known as ''scleroproteins''. Alpha-keratin (α-keratin) is a type of keratin found in vertebrates. It is the key structural material making up scales, hair, nails, feathers, ho ...
, the same material as a human
fingernail A nail is a claw-like plate found at the tip of the fingers and toes on most primates. Nails correspond to the claws found in other animals. Fingernails and toenails are made of a tough protective protein called alpha-keratin, which is a polymer ...
. The result is that a horse, weighing on average , travels on the same bones as would a human on tiptoe. For the protection of the hoof under certain conditions, some horses have
horseshoe A horseshoe is a fabricated product designed to protect a horse hoof from wear. Shoes are attached on the palmar surface (ground side) of the hooves, usually nailed through the insensitive hoof wall that is anatomically akin to the human toen ...
s placed on their feet by a professional
farrier A farrier is a specialist in equine hoof care, including the trimming and balancing of horses' hooves and the placing of shoes on their hooves, if necessary. A farrier combines some blacksmith's skills (fabricating, adapting, and adjus ...
. The hoof continually grows, and in most domesticated horses needs to be trimmed (and
horseshoe A horseshoe is a fabricated product designed to protect a horse hoof from wear. Shoes are attached on the palmar surface (ground side) of the hooves, usually nailed through the insensitive hoof wall that is anatomically akin to the human toen ...
s reset, if used) every five to eight weeks, though the hooves of horses in the wild wear down and regrow at a rate suitable for their terrain.


Teeth

Horses are adapted to
grazing In agriculture, grazing is a method of animal husbandry whereby domestic livestock are allowed outdoors to roam around and consume wild vegetations in order to convert the otherwise indigestible (by human gut) cellulose within grass and other ...
. In an adult horse, there are 12 
incisor Incisors (from Latin ''incidere'', "to cut") are the front teeth present in most mammals. They are located in the premaxilla above and on the mandible below. Humans have a total of eight (two on each side, top and bottom). Opossums have 18, whe ...
s at the front of the mouth, adapted to biting off the grass or other vegetation. There are 24 teeth adapted for chewing, the
premolar The premolars, also called premolar teeth, or bicuspids, are transitional teeth located between the canine and molar teeth. In humans, there are two premolars per quadrant in the permanent set of teeth, making eight premolars total in the mouth ...
s and
molars The molars or molar teeth are large, flat teeth at the back of the mouth. They are more developed in mammals. They are used primarily to grind food during chewing. The name ''molar'' derives from Latin, ''molaris dens'', meaning "millstone to ...
, at the back of the mouth. Stallions and geldings have four additional teeth just behind the incisors, a type of
canine teeth In mammalian oral anatomy, the canine teeth, also called cuspids, dog teeth, or (in the context of the upper jaw) fangs, eye teeth, vampire teeth, or vampire fangs, are the relatively long, pointed teeth. They can appear more flattened howeve ...
called "tushes". Some horses, both male and female, will also develop one to four very small
vestigial Vestigiality is the retention, during the process of evolution, of genetically determined structures or attributes that have lost some or all of the ancestral function in a given species. Assessment of the vestigiality must generally rely on co ...
teeth in front of the molars, known as "wolf" teeth, which are generally removed because they can interfere with the
bit The bit is the most basic unit of information in computing and digital communications. The name is a portmanteau of binary digit. The bit represents a logical state with one of two possible values. These values are most commonly represente ...
. There is an empty interdental space between the incisors and the molars where the bit rests directly on the gums, or "bars" of the horse's mouth when the horse is
bridle A bridle is a piece of equipment used to direct a horse. As defined in the ''Oxford English Dictionary'', the "bridle" includes both the that holds a bit that goes in the mouth of a horse, and the reins that are attached to the bit. Headgear w ...
d. An estimate of a horse's age can be made from looking at its teeth. The teeth continue to erupt throughout life and are worn down by grazing. Therefore, the incisors show changes as the horse ages; they develop a distinct wear pattern, changes in tooth shape, and changes in the angle at which the chewing surfaces meet. This allows a very rough estimate of a horse's age, although diet and veterinary care can also affect the rate of tooth wear. Ensminger, pp. 46–50


Digestion

Horses are
herbivore A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthpart ...
s with a digestive system adapted to a
forage Forage is a plant material (mainly plant leaves and stems) eaten by grazing livestock. Historically, the term ''forage'' has meant only plants eaten by the animals directly as pasture, crop residue, or immature cereal crops, but it is also used m ...
diet of grasses and other plant material, consumed steadily throughout the day. Therefore, compared to humans, they have a relatively small stomach but very long intestines to facilitate a steady flow of nutrients. A horse will eat of food per day and, under normal use, drink of
water Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as a ...
. Horses are not
ruminant Ruminants (suborder Ruminantia) are ungulate, hoofed herbivorous grazing or browsing mammals that are able to acquire nutrients from plant-based food by Enteric fermentation, fermenting it in a specialized stomach prior to digestion, principally ...
s, they have only one stomach, like humans, but unlike humans, they can use
cellulose Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of β(1→4) linked D-glucose units. Cellulose is an important structural component of the primary cell wall ...
, a major component of grass. Horses are
hindgut fermenters Hindgut fermentation is a digestive process seen in monogastric herbivores, animals with a simple, single-chambered stomach. Cellulose is digested with the aid of symbiotic bacteria.cecum The cecum or caecum is a pouch within the peritoneum that is considered to be the beginning of the large intestine. It is typically located on the right side of the body (the same side of the body as the appendix (anatomy), appendix, to which i ...
, or "water gut", which food goes through before reaching the
large intestine The large intestine, also known as the large bowel, is the last part of the gastrointestinal tract and of the digestive system in tetrapods. Water is absorbed here and the remaining waste material is stored in the rectum as feces before being r ...
. Horses cannot
vomit Vomiting (also known as emesis and throwing up) is the involuntary, forceful expulsion of the contents of one's stomach through the mouth and sometimes the nose. Vomiting can be the result of ailments like food poisoning, gastroenterit ...
, so digestion problems can quickly cause
colic Colic or cholic () is a form of pain that starts and stops abruptly. It occurs due to muscular contractions of a hollow tube ( small and large intestine, gall bladder, ureter, etc.) in an attempt to relieve an obstruction by forcing content out ...
, a leading cause of death. Horses do not have a
gallbladder In vertebrates, the gallbladder, also known as the cholecyst, is a small hollow organ where bile is stored and concentrated before it is released into the small intestine. In humans, the pear-shaped gallbladder lies beneath the liver, although ...
; however, they seem to tolerate high amounts of fat in their diet despite lack of a gallbladder.


Senses

The horses' senses are based on their status as prey animals, where they must be aware of their surroundings at all times. Ensminger, pp. 309–310 They have the largest eyes of any land mammal, and are lateral-eyed, meaning that their eyes are positioned on the sides of their heads. This means that horses have a range of vision of more than 350°, with approximately 65° of this being
binocular vision In biology, binocular vision is a type of vision in which an animal has two eyes capable of facing the same direction to perceive a single three-dimensional image of its surroundings. Binocular vision does not typically refer to vision where an ...
and the remaining 285°
monocular vision In human species Monocular vision vision is known as seeing and using only one eye in the human species. Depth perception in monocular vision is reduced compared to binocular vision, but still is active primarily due to accommodation of the eye a ...
. Horses have excellent day and
night vision Night vision is the ability to see in low-light conditions, either naturally with scotopic vision or through a night-vision device. Night vision requires both sufficient spectral range and sufficient intensity range. Humans have poor night vi ...
, but they have two-color, or dichromatic vision; their
color vision Color vision, a feature of visual perception, is an ability to perceive differences between light composed of different wavelengths (i.e., different spectral power distributions) independently of light intensity. Color perception is a part of ...
is somewhat like
red-green color blindness Color blindness or color vision deficiency (CVD) is the decreased ability to see color or differences in color. It can impair tasks such as selecting ripe fruit, choosing clothing, and reading traffic lights. Color blindness may make some aca ...
in humans, where certain colors, especially red and related colors, appear as a shade of green. Their
sense of smell The sense of smell, or olfaction, is the special sense through which smells (or odors) are perceived. The sense of smell has many functions, including detecting desirable foods, hazards, and pheromones, and plays a role in taste. In humans, it ...
, while much better than that of humans, is not quite as good as that of a dog. It is believed to play a key role in the social interactions of horses as well as detecting other key scents in the environment. Horses have two olfactory centers. The first system is in the nostrils and nasal cavity, which analyze a wide range of odors. The second, located under the nasal cavity, are the
vomeronasal organ The vomeronasal organ (VNO), or Jacobson's organ, is the paired auxiliary olfactory (smell) sense organ located in the soft tissue of the nasal septum, in the nasal cavity just above the roof of the mouth (the hard palate) in various tetrapods. T ...
s, also called Jacobson's organs. These have a separate nerve pathway to the brain and appear to primarily analyze
pheromone A pheromone () is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting like hormones outside the body of the secreting individual, to affect the behavio ...
s. A horse's hearing is good, and the pinna of each ear can rotate up to 180°, giving the potential for 360° hearing without having to move the head. Noise impacts the behavior of horses and certain kinds of noise may contribute to stress: A 2013 study in the UK indicated that stabled horses were calmest in a quiet setting, or if listening to country or classical music, but displayed signs of nervousness when listening to jazz or rock music. This study also recommended keeping music under a volume of 21
decibel The decibel (symbol: dB) is a relative unit of measurement equal to one tenth of a bel (B). It expresses the ratio of two values of a power or root-power quantity on a logarithmic scale. Two signals whose levels differ by one decibel have a po ...
s. An Australian study found that stabled racehorses listening to talk radio had a higher rate of gastric ulcers than horses listening to music, and racehorses stabled where a radio was played had a higher overall rate of ulceration than horses stabled where there was no radio playing. Horses have a great sense of balance, due partly to their ability to feel their footing and partly to highly developed
proprioception Proprioception ( ), also referred to as kinaesthesia (or kinesthesia), is the sense of self-movement, force, and body position. It is sometimes described as the "sixth sense". Proprioception is mediated by proprioceptors, mechanosensory neurons ...
—the unconscious sense of where the body and limbs are at all times. A horse's
sense of touch In physiology, the somatosensory system is the network of neural structures in the brain and body that produce the perception of touch (haptic perception), as well as temperature (thermoception), body position (proprioception), and pain. It is ...
is well-developed. The most sensitive areas are around the eyes, ears, and nose. Horses are able to sense contact as subtle as an insect landing anywhere on the body. Horses have an advanced sense of taste, which allows them to sort through
fodder Fodder (), also called provender (), is any agriculture, agricultural foodstuff used specifically to feed domesticated livestock, such as cattle, domestic rabbit, rabbits, sheep, horses, chickens and pigs. "Fodder" refers particularly to food g ...
and choose what they would most like to eat, and their
prehensile Prehensility is the quality of an appendage or organ (anatomy), organ that has Adaptation (biology), adapted for grasping or holding. The word is derived from the Latin term ''prehendere'', meaning "to grasp". The ability to grasp is likely der ...
lips can easily sort even small grains. Horses generally will not eat poisonous plants, however, there are exceptions; horses will occasionally eat toxic amounts of poisonous plants even when there is adequate healthy food.


Movement

File:Muybridge horse walking animated.gif, ''Walk'' File:Trot animated.gif, ''Trot'' File:Muybridge_horse_pacing_animated.gif, ''Pace'' File:Canter animated.gif, ''Canter'' File:Muybridge race horse animated.gif, ''Gallop'' , record: All horses move naturally with four basic gaits:
Harris Harris may refer to: Places Canada * Harris, Ontario * Northland Pyrite Mine (also known as Harris Mine) * Harris, Saskatchewan * Rural Municipality of Harris No. 316, Saskatchewan Scotland * Harris, Outer Hebrides (sometimes called the Isle of ...
, p. 32
*the four-beat
walk Walking (also known as ambulation) is one of the main gaits of terrestrial locomotion among legged animals. Walking is typically slower than running and other gaits. Walking is defined by an ' inverted pendulum' gait in which the body vaults ...
, which averages ; *the two-beat trot or jog at (faster for
harness racing Harness racing is a form of horse racing in which the horses race at a specific gait (a trot or a pace). They usually pull a two-wheeled cart called a sulky, or spider, or chariot occupied by a driver. In Europe, and less frequently in Australi ...
horses); *the canter or lope, a three-beat gait that is ; *the
gallop The canter and gallop are variations on the fastest gait that can be performed by a horse or other equine. The canter is a controlled three-beat gait, while the gallop is a faster, four-beat variation of the same gait. It is a natural gait pos ...
, which averages ,
Harris Harris may refer to: Places Canada * Harris, Ontario * Northland Pyrite Mine (also known as Harris Mine) * Harris, Saskatchewan * Rural Municipality of Harris No. 316, Saskatchewan Scotland * Harris, Outer Hebrides (sometimes called the Isle of ...
, pp. 47–49
but the world record for a horse galloping over a short, sprint distance is . Besides these basic gaits, some horses perform a two-beat
pace Pace or paces may refer to: Business *Pace (transit), a bus operator in the suburbs of Chicago, US * Pace Airlines, an American charter airline *Pace Foods, a maker of a popular brand of salsa sold in North America, owned by Campbell Soup Compan ...
, instead of the trot.
Harris Harris may refer to: Places Canada * Harris, Ontario * Northland Pyrite Mine (also known as Harris Mine) * Harris, Saskatchewan * Rural Municipality of Harris No. 316, Saskatchewan Scotland * Harris, Outer Hebrides (sometimes called the Isle of ...
, p. 50
There also are several four-beat ' ambling' gaits that are approximately the speed of a trot or pace, though smoother to ride. These include the lateral
rack Rack or racks may refer to: Storage and installation * Amp rack, short for amplifier rack, a piece of furniture in which amplifiers are mounted * Bicycle rack, a frame for storing bicycles when not in use * Bustle rack, a type of storage bi ...
, running walk, and
tölt An ambling gait or amble is any of several four-beat intermediate horse gaits, all of which are faster than a walk but usually slower than a canter and always slower than a gallop. Horses that amble are sometimes referred to as " gaited", partic ...
as well as the diagonal
fox trot The foxtrot is a smooth, progressive dance characterized by long, continuous flowing movements across the dance floor. It is danced to big band (usually vocal) music. The dance is similar in its look to waltz, although the rhythm is in a tim ...
. Ambling gaits are often genetic in some breeds, known collectively as
gaited horse Gaited horses are horse breeds that have selective breeding for natural gaited tendencies, that is, the ability to perform one of the smooth-to-ride, intermediate speed, four-beat horse gaits, collectively referred to as ''ambling gaits''. In mos ...
s. These horses replace the trot with one of the ambling gaits.
Harris Harris may refer to: Places Canada * Harris, Ontario * Northland Pyrite Mine (also known as Harris Mine) * Harris, Saskatchewan * Rural Municipality of Harris No. 316, Saskatchewan Scotland * Harris, Outer Hebrides (sometimes called the Isle of ...
, pp. 50–55


Behavior

Horses are prey animals with a strong
fight-or-flight response The fight-or-flight or the fight-flight-or-freeze response (also called hyperarousal or the acute stress response) is a physiological reaction that occurs in response to a perceived harmful event, attack, or threat to survival. It was first des ...
. Their first reaction to a threat is to startle and usually flee, although they will stand their ground and defend themselves when flight is impossible or if their young are threatened. They also tend to be curious; when startled, they will often hesitate an instant to ascertain the cause of their fright, and may not always flee from something that they perceive as non-threatening. Most light horse riding breeds were developed for speed, agility, alertness and endurance; natural qualities that extend from their wild ancestors. However, through selective breeding, some breeds of horses are quite docile, particularly certain draft horses. Horses are
herd animal A herd is a social group of certain animals of the same species, either wild or domestic. The form of collective animal behavior associated with this is called ''herding''. These animals are known as gregarious animals. The term ''herd'' is ...
s, with a clear hierarchy of rank, led by a dominant individual, usually a mare. They are also social creatures that are able to form companionship attachments to their own species and to other animals, including humans. They communicate in various ways, including vocalizations such as nickering or whinnying, mutual grooming, and
body language Body language is a type of communication in which physical behaviors, as opposed to words, are used to express or convey information. Such behavior includes facial expressions, body posture, gestures, eye movement, touch and the use of space. Th ...
. Many horses will become difficult to manage if they are isolated, but with training, horses can learn to accept a human as a companion, and thus be comfortable away from other horses. Ensminger, pp. 305–309 However, when confined with insufficient companionship, exercise, or stimulation, individuals may develop
stable vices Stable vices are stereotypies of equines, especially horses. They are usually undesirable habits that often develop as a result of being confined in a stable with boredom, hunger, isolation, excess energy, or insufficient exercise. They present ...
, an assortment of bad habits, mostly stereotypies of psychological origin, that include wood chewing, wall kicking, "weaving" (rocking back and forth), and other problems.


Intelligence and learning

Studies have indicated that horses perform a number of
cognitive Cognition refers to "the mental action or process of acquiring knowledge and understanding through thought, experience, and the senses". It encompasses all aspects of intellectual functions and processes such as: perception, attention, thought, ...
tasks on a daily basis, meeting mental challenges that include food procurement and identification of individuals within a
social system In sociology, a social system is the patterned network of relationships constituting a coherent whole that exist between individuals, groups, and institutions. It is the formal structure of role and status that can form in a small, stable group. ...
. They also have good spatial discrimination abilities. They are naturally curious and apt to investigate things they have not seen before. Studies have assessed equine intelligence in areas such as
problem solving Problem solving is the process of achieving a goal by overcoming obstacles, a frequent part of most activities. Problems in need of solutions range from simple personal tasks (e.g. how to turn on an appliance) to complex issues in business an ...
, speed of learning, and
memory Memory is the faculty of the mind by which data or information is encoded, stored, and retrieved when needed. It is the retention of information over time for the purpose of influencing future action. If past events could not be remembered, ...
. Horses excel at simple learning, but also are able to use more advanced cognitive abilities that involve
categorization Categorization is the ability and activity of recognizing shared features or similarities between the elements of the experience of the world (such as Object (philosophy), objects, events, or ideas), organizing and classifying experience by a ...
and
concept learning Concept learning, also known as category learning, concept attainment, and concept formation, is defined by Bruner, Goodnow, & Austin (1967) as "the search for and listing of attributes that can be used to distinguish exemplars from non exemplars ...
. They can learn using
habituation Habituation is a form of non-associative learning in which an innate (non-reinforced) response to a stimulus decreases after repeated or prolonged presentations of that stimulus. Responses that habituate include those that involve the intact org ...
, desensitization,
classical conditioning Classical conditioning (also known as Pavlovian or respondent conditioning) is a behavioral procedure in which a biologically potent stimulus (e.g. food) is paired with a previously neutral stimulus (e.g. a triangle). It also refers to the learni ...
, and
operant conditioning Operant conditioning, also called instrumental conditioning, is a learning process where behaviors are modified through the association of stimuli with reinforcement or punishment. In it, operants—behaviors that affect one's environment—are c ...
, and positive and negative
reinforcement In behavioral psychology, reinforcement is a consequence applied that will strengthen an organism's future behavior whenever that behavior is preceded by a specific antecedent stimulus. This strengthening effect may be measured as a higher freq ...
. One study has indicated that horses can differentiate between "more or less" if the quantity involved is less than four. Domesticated horses may face greater mental challenges than wild horses, because they live in artificial environments that prevent
instinct Instinct is the inherent inclination of a living organism towards a particular complex behaviour, containing both innate (inborn) and learned elements. The simplest example of an instinctive behaviour is a fixed action pattern (FAP), in which a v ...
ive behavior whilst also learning tasks that are not natural. Horses are animals of
habit A habit (or wont as a humorous and formal term) is a routine of behavior that is repeated regularly and tends to occur subconsciously.
that respond well to regimentation, and respond best when the same routines and techniques are used consistently. One trainer believes that "intelligent" horses are reflections of intelligent trainers who effectively use response conditioning techniques and positive reinforcement to train in the style that best fits with an individual animal's natural inclinations.


Temperament

Horses are
mammal Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or ...
s, and as such are
warm-blooded Warm-blooded is an informal term referring to animal species which can maintain a body temperature higher than their environment. In particular, homeothermic species maintain a stable body temperature by regulating metabolic processes. The onl ...
, or
endotherm An endotherm (from Greek ἔνδον ''endon'' "within" and θέρμη ''thermē'' "heat") is an organism that maintains its body at a metabolically favorable temperature, largely by the use of heat released by its internal bodily functions inste ...
ic creatures, as opposed to cold-blooded, or
poikilotherm A poikilotherm () is an animal whose internal temperature varies considerably. Poikilotherms have to survive and adapt to environmental stress. One of the most important stressors is temperature change, which can lead to alterations in membrane ...
ic animals. However, these words have developed a separate meaning in the context of equine terminology, used to describe temperament, not
body temperature Thermoregulation is the ability of an organism to keep its body temperature within certain boundaries, even when the surrounding temperature is very different. A thermoconforming organism, by contrast, simply adopts the surrounding temperature ...
. For example, the "hot-bloods", such as many
race horses Race Horses were a Welsh band based in Cardiff, Wales and originally from Aberystwyth. Formed in 2005 as Radio Luxembourg, they changed their name in 2009 due to possible legal problems with the radio station of the same name. Initially the m ...
, exhibit more sensitivity and energy, Belknap, p. 255 while the "cold-bloods", such as most draft breeds, are quieter and calmer. Belknap, p. 112 Sometimes "hot-bloods" are classified as "light horses" or "riding horses", Ensminger, pp. 71–73 with the "cold-bloods" classified as "draft horses" or "work horses". Ensminger, p. 84 "Hot blooded" breeds include "
oriental horse The term oriental horse refers to the ancient breeds of horses developed in the Middle East, such as the Arabian, Akhal-Teke, Barb, and the now-extinct Turkoman horse. They tend to be thin-skinned, long-legged, slim in build and more physically ...
s" such as the
Akhal-Teke The Akhal-Teke ( or ; from Turkmen ''Ahalteke'', ) is a Turkmen horse breed. They have a reputation for speed and endurance, intelligence, and a distinctive metallic sheen. The shiny coat of the breed led to their nickname, "Golden Horses". ...
,
Arabian horse The Arabian or Arab horse ( ar, الحصان العربي , DIN 31635, DMG ''ḥiṣān ʿarabī'') is a horse breed, breed of horse that originated on the Arabian Peninsula. With a distinctive head shape and high tail carriage, the Arabian is ...
,
Barb Barb or the BARBs or ''variation'' may refer to: People * Barb (name), a list of people and fictional characters with the given name or surname * Barb, a term used by fans of Nicki Minaj to refer to themselves * The Barbs, a band Places * Barb, ...
, and now-extinct
Turkoman horse The Turkoman horse, or Turkmene, was an Oriental horse breed from the steppes of Turkoman desert. Its closest modern descendant is thought to be the Akhal-Teke. It influenced many modern horse breeds, including the Thoroughbred horse. Some h ...
, as well as the
Thoroughbred The Thoroughbred is a horse breed best known for its use in 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 c ...
, a breed developed in England from the older oriental breeds. Hot bloods tend to be spirited, bold, and learn quickly. They are bred for agility and speed. They tend to be physically refined—thin-skinned, slim, and long-legged. The original oriental breeds were brought to Europe from the Middle East and North Africa when European breeders wished to infuse these traits into racing and light
cavalry Historically, cavalry (from the French word ''cavalerie'', itself derived from "cheval" meaning "horse") are soldiers or warriors who fight mounted on horseback. Cavalry were the most mobile of the combat arms, operating as light cavalry ...
horses.
Whitaker Whitaker (also Whittaker) is a surname of English and Scottish origin, meaning the white acre, also spelled "Whittaker" and " Whitacre." Notable people with the surname include: People with the name * The Whitaker iron family - a family important ...
, p. 43
Whitaker Whitaker (also Whittaker) is a surname of English and Scottish origin, meaning the white acre, also spelled "Whittaker" and " Whitacre." Notable people with the surname include: People with the name * The Whitaker iron family - a family important ...
, pp. 194–197
Muscular, heavy
draft horse A draft horse (US), draught horse (UK) or dray horse (from the Old English ''dragan'' meaning "to draw or haul"; compare Dutch ''dragen'' and German ''tragen'' meaning "to carry" and Danish ''drage'' meaning "to draw" or "to fare"), less often ...
s are known as "cold bloods", as they are bred not only for strength, but also to have the calm, patient temperament needed to pull a plow or a heavy carriage full of people. They are sometimes nicknamed "gentle giants".
Price A price is the (usually not negative) quantity of payment or compensation given by one party to another in return for goods or services. In some situations, the price of production has a different name. If the product is a "good" in the c ...
, p. 15
Well-known draft breeds include the
Belgian Belgian may refer to: * Something of, or related to, Belgium * Belgians, people from Belgium or of Belgian descent * Languages of Belgium, languages spoken in Belgium, such as Dutch, French, and German *Ancient Belgian language, an extinct languag ...
and the
Clydesdale Clydesdale is an archaic name for Lanarkshire, a traditional county in Scotland. The name may also refer to: Sports * Clydesdale F.C., a former football club in Glasgow * Clydesdale RFC, Glasgow, a former rugby union club * Clydesdale RFC, South ...
. Some, like the
Percheron The Percheron is a breed of draft horse that originated in the Huisne river valley in western France, part of the former Perche province from which the breed takes its name. Usually gray or black in color, Percherons are well muscled, and ...
, are lighter and livelier, developed to pull carriages or to plow large fields in drier climates. Bongianni, entry 87 Others, such as the
Shire Shire is a traditional term for an administrative division of land in Great Britain and some other English-speaking countries such as Australia and New Zealand. It is generally synonymous with county. It was first used in Wessex from the beginn ...
, are slower and more powerful, bred to plow fields with heavy, clay-based soils. Ensminger, pp. 124–125 The cold-blooded group also includes some pony breeds. "
Warmblood Warmbloods are a group of middle-weight horse types and breeds primarily originating in Europe and registered with organizations that are characterized by open studbook policy, studbook selection, and the aim of breeding for equestrian sport. ...
" breeds, such as the
Trakehner Trakehner is a light warmblood breed of horse, originally developed at the East Prussian state stud farm in the town of Trakehnen from which the breed takes its name. The state stud ( :de:Hauptgestüt Trakehnen) was established in 1731 and ...
or Hanoverian, developed when European carriage and war horses were crossed with Arabians or Thoroughbreds, producing a riding horse with more refinement than a draft horse, but greater size and milder temperament than a lighter breed. Certain
pony A pony is a type of small horse ('' Equus ferus caballus''). Depending on the context, a pony may be a horse that is under an approximate or exact height at the withers, or a small horse with a specific conformation and temperament. Compared ...
breeds with warmblood characteristics have been developed for smaller riders. Warmbloods are considered a "light horse" or "riding horse". Today, the term "Warmblood" refers to a specific subset of
sport horse A sport horse or sporthorse is a type of horse, rather than any particular breed. The term is usually applied to horses bred for the traditional Olympic equestrian sporting events of dressage, eventing, show jumping, and combined driving, but ...
breeds that are used for competition in
dressage Dressage ( or ; a French term, most commonly translated to mean "training") is a form of horse riding performed in exhibition and competition, as well as an art sometimes pursued solely for the sake of mastery. As an equestrian sport defined b ...
and
show jumping Show jumping is a part of a group of English riding equestrianism, equestrian events that also includes dressage, eventing, Show hunter, hunters, and equitation. Jumping classes are commonly seen at horse shows throughout the world, including th ...
. Strictly speaking, the term " warm blood" refers to any
cross A cross is a geometrical figure consisting of two intersecting lines or bars, usually perpendicular to each other. The lines usually run vertically and horizontally. A cross of oblique lines, in the shape of the Latin letter X, is termed a sa ...
between cold-blooded and hot-blooded breeds. Belknap, p. 523 Examples include breeds such as the
Irish Draught The Irish Draught horse is the national horse breed of Ireland which developed primarily for farm use. Today, they are especially popular for crossing with Thoroughbreds and warmbloods, producing the popular Irish Sport Horses (also called ...
or the
Cleveland Bay The Cleveland Bay is a breed of horse that originated in England during the 17th century, named after its colouring and the Cleveland district of Yorkshire. It is a well-muscled horse, with legs that are strong but short in relation ...
. The term was once used to refer to breeds of light riding horse other than Thoroughbreds or Arabians, such as the
Morgan horse The Morgan horse is one of the earliest horse breeds developed in the United States. Tracing back to the foundation sire Figure, later named Justin Morgan after his best-known owner, Morgans served many roles in 19th-century American histo ...
.
Price A price is the (usually not negative) quantity of payment or compensation given by one party to another in return for goods or services. In some situations, the price of production has a different name. If the product is a "good" in the c ...
, p. 18


Sleep patterns

Horses are able to sleep both standing up and lying down. In an adaptation from life in the wild, horses are able to enter light sleep by using a " stay apparatus" in their legs, allowing them to doze without collapsing. Horses sleep better when in groups because some animals will sleep while others stand guard to watch for predators. A horse kept alone will not sleep well because its
instinct Instinct is the inherent inclination of a living organism towards a particular complex behaviour, containing both innate (inborn) and learned elements. The simplest example of an instinctive behaviour is a fixed action pattern (FAP), in which a v ...
s are to keep a constant eye out for danger. Unlike humans, horses do not sleep in a solid, unbroken period of time, but take many short periods of rest. Horses spend four to fifteen hours a day in standing rest, and from a few minutes to several hours lying down. Total sleep time in a 24-hour period may range from several minutes to a couple of hours, mostly in short intervals of about 15 minutes each. Ensminger, p. 310. The average sleep time of a domestic horse is said to be 2.9 hours per day. Horses must lie down to reach
REM sleep Rapid eye movement sleep (REM sleep or REMS) is a unique phase of sleep in mammals and birds, characterized by random rapid movement of the eyes, accompanied by low muscle tone throughout the body, and the propensity of the sleeper to dream viv ...
. They only have to lie down for an hour or two every few days to meet their minimum REM sleep requirements. However, if a horse is never allowed to lie down, after several days it will become sleep-deprived, and in rare cases may suddenly collapse as it involuntarily slips into REM sleep while still standing. This condition differs from
narcolepsy Narcolepsy is a long-term neurological disorder that involves a decreased ability to regulate sleep–wake cycles. Symptoms often include periods of excessive daytime sleepiness and brief involuntary sleep episodes. About 70% of those affec ...
, although horses may also suffer from that disorder.


Taxonomy and evolution

The horse Adaptation, adapted to survive in areas of wide-open terrain with sparse vegetation, surviving in an ecosystem where other large grazing animals, especially
ruminant Ruminants (suborder Ruminantia) are ungulate, hoofed herbivorous grazing or browsing mammals that are able to acquire nutrients from plant-based food by Enteric fermentation, fermenting it in a specialized stomach prior to digestion, principally ...
s, could not. Horses and other equids are odd-toed ungulates of the Order (biology), order ''Perissodactyla'', a group of mammals dominant during the Tertiary period. In the past, this order contained 14 Family (biology), families, but only three—
Equidae Equidae (sometimes known as the horse family) is the taxonomic family of horses and related animals, including the extant horses, asses, and zebras, and many other species known only from fossils. All extant species are in the genus '' Equus'', ...
(the horse and related species), Tapiridae (the tapir), and Rhinocerotidae (the rhinoceroses)—have survived to the present day. The earliest known member of the family Equidae was the ''Hyracotherium'', which lived between 45 and 55 million years ago, during the Eocene period. It had 4 toes on each front foot, and 3 toes on each back foot. The extra toe on the front feet soon disappeared with the ''Mesohippus'', which lived 32 to 37 million years ago. Over time, the extra side toes shrank in size until they vanished. All that remains of them in modern horses is a set of small Vestigiality, vestigial bones on the leg below the knee, known informally as splint bones. Their legs also lengthened as their toes disappeared until they were a hooved animal capable of running at great speed. By about 5 million years ago, the modern ''Equus'' had evolved. Equid teeth also evolved from browsing on soft, tropical plants to adapt to browsing of drier plant material, then to grazing of tougher plains grasses. Thus proto-horses changed from leaf-eating forest-dwellers to grass-eating inhabitants of semi-arid regions worldwide, including the steppes of Eurasia and the Great Plains of North America. By about 15,000 years ago, ''Equus ferus'' was a widespread holarctic species. Horse bones from this time period, the late Pleistocene, are found in Europe, Eurasia, Beringia, and North America. Yet between 10,000 and 7,600 years ago, the horse became extinct in North America and rare elsewhere. The reasons for this extinction are not fully known, but one theory notes that extinction in North America paralleled human arrival. Another theory points to climate change, noting that approximately 12,500 years ago, the grasses characteristic of a steppe ecosystem gave way to shrub tundra, which was covered with unpalatable plants.


Wild species surviving into modern times

A truly
wild horse The wild horse (''Equus ferus'') is a species of the genus ''Equus'', which includes as subspecies the modern domesticated horse (''Equus ferus caballus'') as well as the endangered Przewalski's horse (''Equus ferus przewalskii''). The Europea ...
is a species or subspecies with no ancestors that were ever domesticated. Therefore, most "wild" horses today are actually
feral horse A feral horse is a free-roaming horse of domesticated stock. As such, a feral horse is not a wild animal in the sense of an animal without domesticated ancestors. However, some populations of feral horses are managed as wildlife, and these ...
s, animals that escaped or were turned loose from domestic herds and the descendants of those animals. Only two wild subspecies, the tarpan and the Przewalski's horse, survived into recorded history and only the latter survives today. The Przewalski's horse (''Equus ferus przewalskii''), named after the Russian explorer Nikolai Przhevalsky, is a rare Asian animal. It is also known as the Mongolian wild horse; Mongolian people know it as the ''taki'', and the Kyrgyz people call it a ''kirtag''. The subspecies was presumed extinct in the wild between 1969 and 1992, while a small breeding population survived in zoos around the world. In 1992, it was reestablished in the wild by the conservation efforts of numerous zoos. Today, a small wild breeding population exists in Mongolia.#Dohner, Dohner, pp. 298–299 There are additional animals still maintained at zoos throughout the world. The question of whether the Przewalski's horse was ever domesticated was challenged in 2018 when DNA studies of horses found at Botai culture sites revealed captured animals with DNA markers of an ancestor to the Przewalski's horse. The study concluded that the Botai animals appear to have been an independent domestication attempt involving a different wild population from all other domesticated horses. However, the question of whether all Przewalski's horses descend from this domesticated population is unresolved, as only one of seven modern Przewalski’s horses in the study shared this ancestry. The tarpan or European wild horse (''Equus ferus ferus'') was found in Europe and much of Asia. It survived into the historical era, but became Extinction, extinct in 1909, when the last captive died in a Russian zoo.#Dohner, Dohner, p. 300 Thus, the genetic line was lost. Attempts have been made to recreate the tarpan, which resulted in horses with outward physical similarities, but nonetheless descended from domesticated ancestors and not true wild horses. Periodically, populations of horses in isolated areas are speculated to be Relict (biology), relict populations of wild horses, but generally have been proven to be feral or domestic. For example, the Riwoche horse of Tibet was proposed as such, but testing did not reveal genetic differences from domesticated horses. Similarly, the Sorraia of Portugal was proposed as a direct descendant of the Tarpan on the basis of shared characteristics,#Edwards, Edwards, pp. 104–105 but genetic studies have shown that the Sorraia is more closely related to other horse breeds, and that the outward similarity is an unreliable measure of relatedness.


Other modern equids

Besides the horse, there are six other species of genus ''Equus'' in the Equidae family (biology), family. These are the ass or donkey, ''Equus asinus''; the mountain zebra, ''Equus zebra''; plains zebra, ''Equus quagga''; Grévy's Zebra, ''Equus grevyi''; the kiang, ''Equus kiang''; and the onager, ''Equus hemionus''. Horses can crossbreed with other members of their genus. The most common Hybrid (biology), hybrid is the mule, a cross between a "jack" (male donkey) and a
mare A mare is an adult female horse or other equine. In most cases, a mare is a female horse over the age of three, and a filly is a female horse three and younger. In Thoroughbred horse racing, a mare is defined as a female horse more than four ...
. A related hybrid, a hinny, is a cross between a stallion and a "jenny" (female donkey). Other hybrids include the zorse, a cross between a zebra and a horse. With rare exceptions, most hybrids are infertility, sterile and cannot reproduce.


Domestication

Domestication of the horse most likely took place in central Asia prior to 3500 BCE. Two major sources of information are used to determine where and when the horse was first domesticated and how the domesticated horse spread around the world. The first source is based on Paleontology, palaeological and archaeological discoveries; the second source is a comparison of DNA obtained from modern horses to that from bones and teeth of ancient horse remains. The earliest archaeological evidence for the domestication of the horse comes from sites in Ukraine and Kazakhstan, dating to approximately 4000–3500 BCE. By 3000 BCE, the horse was completely domesticated and by 2000 BCE there was a sharp increase in the number of horse bones found in human settlements in northwestern Europe, indicating the spread of domesticated horses throughout the continent. The most recent, but most irrefutable evidence of domestication comes from sites where horse remains were interred with chariots in graves of the Sintashta and Petrovka settlement, Petrovka cultures 2100 BCE. A 2021 genetic study suggested that most modern domestic horses descend from the lower Volga region, Volga-Don region. Ancient DNA, Ancient horse genomes indicate that these populations influenced almost all local populations as they expanded rapidly throughout Eurasia, beginning about 4,200 years ago. It also shows that certain adaptations were strongly selected due to riding, and that equestrian material culture, including Sintashta culture, Sintashta spoke-wheeled chariots spread with the horse itself. Domestication is also studied by using the genetic material of present-day horses and comparing it with the genetic material present in the bones and teeth of horse remains found in archaeological and palaeological excavations. The variation in the genetic material shows that very few wild stallions contributed to the domestic horse, while many mares were part of early domesticated herds. This is reflected in the difference in genetic variation between the DNA that is passed on along the paternal, or sire line (Y-chromosome) versus that passed on along the maternal, or dam line (mitochondrial DNA). There are very low levels of Y-chromosome variability, but a great deal of genetic variation in mitochondrial DNA. There is also regional variation in mitochondrial DNA due to the inclusion of wild mares in domestic herds. Another characteristic of domestication is an increase in coat color variation. In horses, this increased dramatically between 5000 and 3000 BCE. Before the availability of DNA techniques to resolve the questions related to the domestication of the horse, various hypotheses were proposed. One classification was based on body types and conformation, suggesting the presence of four basic prototypes that had adapted to their environment prior to domestication. Another hypothesis held that the four prototypes originated from a single wild species and that all different body types were entirely a result of selective breeding after domestication. However, the lack of a detectable substructure in the horse has resulted in a rejection of both hypotheses.


Feral populations

Feral horses are born and live in the wild, but are descended from domesticated animals. Many populations of
feral horse A feral horse is a free-roaming horse of domesticated stock. As such, a feral horse is not a wild animal in the sense of an animal without domesticated ancestors. However, some populations of feral horses are managed as wildlife, and these ...
s exist throughout the world. Studies of feral herds have provided useful insights into the behavior of prehistoric horses, as well as greater understanding of the instincts and behaviors that drive horses that live in domesticated conditions. There are also semi-feral horses in many parts of the world, such as Dartmoor and the New Forest in the UK, where the animals are all privately owned but live for significant amounts of time in "wild" conditions on undeveloped, often public, lands. Owners of such animals often pay a fee for grazing rights.


Breeds

The concept of purebred bloodstock and a controlled, written breed registry has come to be particularly significant and important in modern times. Sometimes purebred horses are incorrectly or inaccurately called "thoroughbreds".
Thoroughbred The Thoroughbred is a horse breed best known for its use in 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 c ...
is a specific breed of horse, while a "purebred" is a horse (or any other animal) with a defined Pedigree chart, pedigree recognized by a breed registry. Ensminger, p. 424 Horse breeds are groups of horses with distinctive characteristics that are transmitted consistently to their offspring, such as equine conformation, conformation, color, performance ability, or disposition. These inherited traits result from a combination of natural crosses and artificial selection methods. Horses have been Selective breeding, selectively bred since their
domestication Domestication is a sustained multi-generational relationship in which humans assume a significant degree of control over the reproduction and care of another group of organisms to secure a more predictable supply of resources from that group. ...
. An early example of people who practiced selective horse breeding were the Bedouin, who had a reputation for careful practices, keeping extensive pedigrees of their
Arabian horse The Arabian or Arab horse ( ar, الحصان العربي , DIN 31635, DMG ''ḥiṣān ʿarabī'') is a horse breed, breed of horse that originated on the Arabian Peninsula. With a distinctive head shape and high tail carriage, the Arabian is ...
s and placing great value upon pure bloodlines. These pedigrees were originally transmitted via an oral tradition. In the 14th century, Carthusian monks of southern Spain kept meticulous pedigrees of bloodstock lineages still found today in the Andalusian horse. Breeds developed due to a need for "form to function", the necessity to develop certain characteristics in order to perform a particular type of work.#Sponenberg, Sponenberg, p. 155 Thus, a powerful but refined breed such as the Andalusian developed as riding horses with an aptitude for
dressage Dressage ( or ; a French term, most commonly translated to mean "training") is a form of horse riding performed in exhibition and competition, as well as an art sometimes pursued solely for the sake of mastery. As an equestrian sport defined b ...
. Heavy draft horses were developed out of a need to perform demanding farm work and pull heavy wagons. Other horse breeds had been developed specifically for light agricultural work, carriage and road work, various sport disciplines, or simply as pets.#Sponenberg, Sponenberg, p. 162 Some breeds developed through centuries of crossing other breeds, while others descended from a single foundation stock, foundation sire, or other limited or restricted foundation bloodstock. One of the earliest formal registries was General Stud Book for Thoroughbreds, which began in 1791 and traced back to the foundation bloodstock for the breed. There are more than 300 horse breeds in the world today.


Interaction with humans

Worldwide, horses play a role within human cultures and have done so for millennia. Horses are used for leisure activities, sports, and working purposes. The Food and Agriculture Organization (FAO) estimates that in 2008, there were almost 59,000,000 horses in the world, with around 33,500,000 in the Americas, 13,800,000 in Asia and 6,300,000 in Europe and smaller portions in Africa and Oceania. There are estimated to be 9,500,000 horses in the United States alone. The American Horse Council estimates that horse-related activities have a direct impact on the economy of the United States of over $39 billion, and when indirect spending is considered, the impact is over $102 billion. In a 2004 "poll" conducted by Animal Planet, more than 50,000 viewers from 73 countries voted for the horse as the world's 4th favorite animal. Communication between human and horse is paramount in any equestrian activity; to aid this process horses are usually ridden with a
saddle The saddle is a supportive structure for a rider of an animal, fastened to an animal's back by a girth. The most common type is equestrian. However, specialized saddles have been created for oxen, camels and other animals. It is not kno ...
on their backs to assist the rider with balance and positioning, and a
bridle A bridle is a piece of equipment used to direct a horse. As defined in the ''Oxford English Dictionary'', the "bridle" includes both the that holds a bit that goes in the mouth of a horse, and the reins that are attached to the bit. Headgear w ...
or related headgear to assist the rider in maintaining control. Sometimes horses are ridden without a saddle, and occasionally, horses are trained to perform without a bridle or other headgear. Many horses are also Driving (horse), driven, which requires a horse harness, harness, bridle, and some type of horse-drawn vehicle, vehicle.


Sport

Historically, equestrians honed their skills through games and races. Equestrian sports provided entertainment for crowds and honed the excellent horsemanship that was needed in battle. Many sports, such as
dressage Dressage ( or ; a French term, most commonly translated to mean "training") is a form of horse riding performed in exhibition and competition, as well as an art sometimes pursued solely for the sake of mastery. As an equestrian sport defined b ...
, eventing, and
show jumping Show jumping is a part of a group of English riding equestrianism, equestrian events that also includes dressage, eventing, Show hunter, hunters, and equitation. Jumping classes are commonly seen at horse shows throughout the world, including th ...
, have origins in horses in warfare, military training, which were focused on control and balance of both horse and rider. Other sports, such as rodeo, developed from practical skills such as those needed on working ranches and Station (Australian agriculture), stations. Sport hunting from horseback evolved from earlier practical hunting techniques. Horse racing of all types evolved from impromptu competitions between riders or drivers. All forms of competition, requiring demanding and specialized skills from both horse and rider, resulted in the systematic development of specialized breeds and equipment for each sport. The popularity of equestrian sports through the centuries has resulted in the preservation of skills that would otherwise have disappeared after horses stopped being used in combat. Horses are trained to be ridden or driven in a variety of sporting competitions. Examples include
show jumping Show jumping is a part of a group of English riding equestrianism, equestrian events that also includes dressage, eventing, Show hunter, hunters, and equitation. Jumping classes are commonly seen at horse shows throughout the world, including th ...
,
dressage Dressage ( or ; a French term, most commonly translated to mean "training") is a form of horse riding performed in exhibition and competition, as well as an art sometimes pursued solely for the sake of mastery. As an equestrian sport defined b ...
, three-day eventing, combined driving, competitive driving,
endurance riding Endurance riding is an equestrian sport based on controlled long-distance races. It is one of the international competitions recognized by the FEI. There are endurance rides worldwide. Endurance rides can be any distance, though they are rare ...
, Gymkhana (equestrian), gymkhana, rodeos, and fox hunting. Horse shows, which have their origins in medieval European fairs, are held around the world. They host a huge range of classes, covering all of the mounted and harness disciplines, as well as halter (horse show), "In-hand" classes where the horses are led, rather than ridden, to be evaluated on their conformation. The method of judging varies with the discipline, but winning usually depends on style and ability of both horse and rider. Sports such as polo do not judge the horse itself, but rather use the horse as a partner for human competitors as a necessary part of the game. Although the horse requires specialized training to participate, the details of its performance are not judged, only the result of the rider's actions—be it getting a ball through a goal or some other task.#Edwards, Edwards, p. 360 Examples of these sports of partnership between human and horse include jousting, in which the main goal is for one rider to unseat the other, and buzkashi, a team game played throughout Central Asia, the aim being to capture a goat carcass while on horseback. Horse racing is an equestrian sport and major international industry, watched in almost every nation of the world. There are three types: "flat" racing; Steeplechase (horse racing), steeplechasing, i.e. racing over jumps; and
harness racing Harness racing is a form of horse racing in which the horses race at a specific gait (a trot or a pace). They usually pull a two-wheeled cart called a sulky, or spider, or chariot occupied by a driver. In Europe, and less frequently in Australi ...
, where horses trot or pace while pulling a driver in a small, light cart known as a sulky. A major part of horse racing's economic importance lies in the Gambling#Parimutuel betting, gambling associated with it.


Work

There are certain jobs that horses do very well, and no technology has yet developed to fully replace them. For example, mounted police horses are still effective for certain types of patrol duties and crowd control. Cattle ranches still require riders on horseback to round up cattle that are scattered across remote, rugged terrain. Search and rescue organizations in some countries depend upon mounted search and rescue, mounted teams to locate people, particularly hikers and children, and to provide disaster relief assistance. Horses can also be used in areas where it is necessary to avoid vehicular disruption to delicate soil, such as nature reserves. They may also be the only form of transport allowed in wilderness areas. Horses are quieter than motorized vehicles. Law enforcement officers such as park rangers or game wardens may use horses for patrols, and horses or mules may also be used for clearing trails or other work in areas of rough terrain where vehicles are less effective. Although machinery has replaced horses in many parts of the world, an estimated 100 million horses, donkeys and mules are still used for agriculture and transportation in less developed areas. This number includes around 27 million working animals in Africa alone. Some land management practices such as cultivating and logging can be efficiently performed with horses. In agriculture, less fossil fuel is used and increased environmental conservation occurs over time with the use of working animal, draft animals such as horses. Logging with horses can result in reduced damage to soil structure and less damage to trees due to more selective logging.


Warfare

Horses have been used in warfare for most of recorded history. The first archaeological evidence of horses used in warfare dates to between 4000 and 3000 BCE, and the use of horses in warfare was widespread by the end of the Bronze Age.
Whitaker Whitaker (also Whittaker) is a surname of English and Scottish origin, meaning the white acre, also spelled "Whittaker" and " Whitacre." Notable people with the surname include: People with the name * The Whitaker iron family - a family important ...
, pp. 30–31
Although mechanization has largely replaced the horse as a weapon of war, horses are still seen today in limited military uses, mostly for ceremonial purposes, or for reconnaissance and transport activities in areas of rough terrain where motorized vehicles are ineffective. Horses have been used in the 21st century by the Janjaweed militias in the War in Darfur.


Entertainment and culture

Modern horses are often used to reenact many of their historical work purposes. Horses are used, complete with equipment that is authentic or a meticulously recreated replica, in various live action historical reenactments of specific periods of history, especially recreations of famous battles. Horses are also used to preserve cultural traditions and for ceremonial purposes. Countries such as the United Kingdom still use horse-drawn carriages to convey royalty and other VIPs to and from certain culturally significant events. Public exhibitions are another example, such as the Budweiser Clydesdales, seen in parades and other public settings, a team of
draft horse A draft horse (US), draught horse (UK) or dray horse (from the Old English ''dragan'' meaning "to draw or haul"; compare Dutch ''dragen'' and German ''tragen'' meaning "to carry" and Danish ''drage'' meaning "to draw" or "to fare"), less often ...
s that pull a beer wagon similar to that used before the invention of the modern motorized truck. Horses are frequently used in television, films and literature. They are sometimes featured as a major character in films about particular animals, but also used as visual elements that assure the accuracy of historical stories. Both live horses and Cultural icon, iconic images of horses are used in advertising to promote a variety of products. The horse frequently appears in coats of arms in heraldry, in a variety of poses and equipment. The mythology, mythologies of many cultures, including Greco-Roman mythology, Greco-Roman, Hindu mythology, Hindu, Islamic mythology, Islamic, and Norse mythology, Norse, include references to both normal horses and those with wings or additional limbs, and multiple myths also call upon the horse to draw the chariots of the Moon and Sun. The horse also appears in the 12-year cycle of animals in the Chinese astrology, Chinese zodiac related to the Chinese calendar. Horses serve as the inspiration for many modern automobile names and logos, including the Ford Pinto, Ford Bronco, Ford Mustang, Hyundai Equus, Hyundai Pony, Mitsubishi Starion, Subaru BRAT, Subaru Brumby, Mitsubishi Colt/Dodge Colt, Volkswagen Polo, Steyr-Puch Pinzgauer, Pinzgauer, Steyr-Puch Haflinger, Pegaso, Porsche, Rolls-Royce Camargue, Ferrari, Carlsson (car company), Carlsson, Kamaz, Corre La Licorne, Iran Khodro, Eicher Motors, Eicher, and Baojun.


Therapeutic use

People of all ages with physical and mental disabilities obtain beneficial results from an association with horses. Therapeutic riding is used to mentally and physically stimulate disabled persons and help them improve their lives through improved balance and coordination, increased self-confidence, and a greater feeling of freedom and independence. The benefits of equestrian activity for people with disabilities has also been recognized with the addition of equestrian events to the Paralympic Games and recognition of para-equestrian events by the
International Federation for Equestrian Sports The International Federation for Equestrian Sports (, FEI) is the international governing body of equestrian sports. The FEI headquarters are in Lausanne, Switzerland. An FEI code of conduct protects the welfare of the horses from physical abu ...
(FEI). Hippotherapy and therapeutic horseback riding are names for different physical, occupational, and speech therapy treatment strategies that use equine movement. In hippotherapy, a therapist uses the horse's movement to improve their patient's cognitive, coordination, balance, and fine motor skills, whereas therapeutic horseback riding uses specific riding skills. Horses also provide psychological benefits to people whether they actually ride or not. "Equine-assisted" or "equine-facilitated" therapy is a form of experiential psychotherapy that uses horses as companion animals to assist people with mental illness, including anxiety disorders, psychotic disorders, mood disorders, behavioral difficulties, and those who are going through major life changes. There are also experimental programs using horses in prison settings. Exposure to horses appears to improve the behavior of inmates and help reduce recidivism when they leave.


Products

Horses are raw material for many products made by humans throughout history, including byproducts from the horse slaughter, slaughter of horses as well as materials collected from living horses. Products collected from living horses include mare's milk, used by people with large horse herds, such as the Mongols, who let it ferment to produce kumis. Horse blood was once used as food by the Mongols and other nomadic tribes, who found it a convenient source of nutrition when traveling. Drinking their own horses' blood allowed the Mongols to ride for extended periods of time without stopping to eat. The drug Premarin is a mixture of estrogens extracted from the urine of pregnant mares (pregnant mares' urine), and was previously a widely used drug for hormone replacement therapy. The tail hair of horses can be used for making bow (music), bows for string instruments such as the violin, viola, cello, and double bass. Horse meat has been used as food for humans and carnivore, carnivorous animals throughout the ages. Approximately 5 million horses are slaughtered each year for meat worldwide. It is eaten in many parts of the world, though consumption is taboo in some cultures, and a subject of political controversy in others. Horsehide leather has been used for boots, gloves, A-2 jacket, jackets, Baseball (ball), baseballs, and baseball gloves. Horse hooves can also be used to produce animal glue. Horse bones can be used to make implements. Specifically, in Italian cuisine, the horse tibia is sharpened into a probe called a ''spinto'', which is used to test the readiness of a (pig) ham as it cures. In Asia, the ''saba'' is a horsehide vessel used in the production of kumis.


Care

Horses are
grazing In agriculture, grazing is a method of animal husbandry whereby domestic livestock are allowed outdoors to roam around and consume wild vegetations in order to convert the otherwise indigestible (by human gut) cellulose within grass and other ...
animals, and their major source of nutrients is good-quality
forage Forage is a plant material (mainly plant leaves and stems) eaten by grazing livestock. Historically, the term ''forage'' has meant only plants eaten by the animals directly as pasture, crop residue, or immature cereal crops, but it is also used m ...
from hay or pasture. They can consume approximately 2% to 2.5% of their body weight in dry feed each day. Therefore, a adult horse could eat up to of food. Sometimes, concentrated feed such as Cereal, grain is fed in addition to pasture or hay, especially when the animal is very active. When grain is fed, equine nutritionists recommend that 50% or more of the animal's diet by weight should still be forage. Horses require a plentiful supply of clean water, a minimum of per day. Although horses are adapted to live outside, they require shelter from the wind and precipitation, which can range from a simple shed or shelter to an elaborate stable. Horses require routine
hoof The hoof (plural: hooves) is the tip of a toe of an ungulate mammal, which is covered and strengthened with a thick and horny keratin covering. Artiodactyls are even-toed ungulates, species whose feet have an even number of digits, yet the rumin ...
care from a
farrier A farrier is a specialist in equine hoof care, including the trimming and balancing of horses' hooves and the placing of shoes on their hooves, if necessary. A farrier combines some blacksmith's skills (fabricating, adapting, and adjus ...
, as well as vaccinations to protect against various diseases, and horse teeth, dental examinations from a
veterinarian A veterinarian (vet), also known as a veterinary surgeon or veterinary physician, is a medical professional who practices veterinary medicine. They manage a wide range of health conditions and injuries in non-human animals. Along with this, vet ...
or a specialized equine dentist. If horses are kept inside in a barn, they require regular daily exercise for their physical health and mental well-being. When turned outside, they require well-maintained, sturdy agricultural fencing, fences to be safely contained. Regular horse grooming, grooming is also helpful to help the horse maintain good health of the hair coat and underlying skin.#Giffin, Giffin, p. 90


See also

* Glossary of equestrian terms * Lists of horse-related topics


References


Sources

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Further reading

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External links


"Ancient horse bone yields oldest DNA sequence"
* *
Genome of ''Equus caballus''
via Ensembl
Genome of ''Equus caballus'' (version EquCab3.0/equCab3)
via UCSC Genome Browser
Data of the genome of ''Equus caballus''
via NCBI
Data of the genome assembly of ''Equus caballus'' (versión EquCab3.0/equCab3)
via NCBI {{taxonbar, from=Q726 Horses, Animal-powered transport Mammals described in 1758 Taxa named by Carl Linnaeus Equus (genus) Herbivorous mammals Horse subspecies Livestock National symbols of Burkina Faso National symbols of Lesotho National symbols of Mongolia National symbols of Nigeria National symbols of Turkmenistan Pack animals Symbols of New Jersey