Horse

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For other uses, see Horse (disambiguation).

Domestic horse
Conservation status
Domesticated
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Mammalia Order: Perissodactyla Family: Equidae Genus: Equus Species: E. ferus Subspecies: E. f. caballus
Trinomial name
Equus ferus caballus Linnaeus, 1758[1]
Synonyms
48, listed here

The horse (Equus ferus caballus)^[2][3] is a hoofed (ungulate) mammal, a subspecies of one of seven extant species of the family Equidae. The horse has evolved over the past 45 to 55 million years from a small multi-toed creature into the large, single-toed animal of today. Humans began to domesticate horses around 4000 BCE, and their domestication is believed to have been widespread by 3000 BCE; by 2000 BCE the use of domesticated horses had spread throughout the Eurasian continent. Although most horses today are domesticated, there are still endangered populations of the Przewalski's Horse, the only remaining true wild horse, as well as more common feral horses which live in the wild but are descended from domesticated ancestors.

There is an extensive, specialized vocabulary used to describe equine-related concepts, covering everything from anatomy to life stages, size, colors, markings, breeds, locomotion, and behavior. Their anatomy enables them to make use of speed to escape predators and they have a well-developed sense of balance and a strong fight-or-flight instinct. 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. Female horses, called mares, carry their young for approximately 11 months, and a young horse, called a foal, can stand and run shortly following birth. Most domesticated horses begin training under saddle or in 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 horses and some ponies, suitable for slow, heavy work; and "warmbloods", developed from crosses between hot bloods and cold bloods, often focusing on creating breeds for specific riding purposes, particularly in Europe. There are over 300 breeds of horses in the world today, developed for many different uses.

Horses and humans interact in many ways, not only in a wide variety of sport competitions and non-competitive recreational pursuits, but also in working activities including police work, agriculture, entertainment, assisted learning and therapy. Horses were historically used in warfare. A wide variety of riding and driving techniques have been developed, using many different styles of equipment and methods of control. Many products are derived from horses, including meat, milk, hide, hair, 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 veterinarians and farriers.

Contents [hide] 1 Biology 1.1 Age 1.2 Size 1.3 Colors and markings 1.4 Reproduction and development 1.5 Anatomy 1.5.1 Skeletal system 1.5.2 Hooves 1.5.3 Teeth 1.5.4 Digestion 1.5.5 Senses 1.6 Movement 1.7 Behavior 1.7.1 Intelligence and learning 1.7.2 Temperament 1.7.3 Sleep patterns 2 Taxonomy and evolution 2.1 Wild species surviving into modern times 2.2 Other modern equids 3 Domestication 3.1 The "Four Foundations" theory 3.2 Feral populations 3.3 Breeds 3.3.1 Origin of breeds 3.3.2 Purebreds and registries 4 Interaction with humans 4.1 Sport 4.2 Work 4.3 Entertainment and culture 4.4 Assisted learning and therapy 4.5 Warfare 4.6 Products 4.7 Care 5 See also 6 References 7 Sources

Biology

Main article: Equine anatomy

Parts of a horse

Horse anatomy is described by a large number of specific terms, as illustrated by the chart to the right. Specific terms also describe various ages, colors and breeds.

Age

Depending on breed, management and environment, the domestic horse today has a life expectancy of 25 to 30 years.^[4] It is uncommon, but a few animals live into their 40s and, occasionally, beyond.^{[citation needed]} The oldest verifiable record was "Old Billy", a 19th-century horse that lived to the age of 62.^[4][5] In modern times, Sugar Puff, who had been listed in the Guinness Book of World Records as the world's oldest living pony, died in 2007, aged 56.^[6]

Regardless of a horse's actual birth date, for most competition purposes an animal is considered a year older on January 1 of each year in the northern hemisphere^[4][7] and August 1 in the southern hemisphere.^[8] The exception is in endurance riding, where the minimum age to compete is based on the animal's calendar age.^[9] A very rough estimate of a horse's age can be made from looking at its teeth.^[4]

The following terminology is used to describe horses of various ages:

• Foal: 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.^[10] Most domesticated foals are weaned at 5 to 7 months of age, although foals can be weaned at 4 months with no adverse effects.^[11]
• Yearling: a horse of either sex that is between one and two years old.^[12]
• Colt: a male horse under the age of four.^[13] A common terminology error is to call any young horse a "colt", when the term actually only refers to young male horses.^{[citation needed]}
• Filly: a female horse under the age of four.^[10]
• Mare: a female horse four years old and older.^[14]
• Stallion: a non-castrated male horse four years old and older.^[15] Some people, particularly in the UK, refer to a stallion as a "horse".^[16]
• Gelding: a castrated male horse of any age,^[10] though for convenience sake, many people also refer to a young gelding under the age of four as a "colt".

In horse racing, the definitions of colt, filly, mare, and stallion may differ from those given above. In the UK, Thoroughbred horse racing defines a colt as a male less than five years old, and a filly as a female less than five years old.^[17] In the United States, both Thoroughbred racing and harness racing defines colts and fillies as four years old and younger.^[18]

Size

Main article: Hand (length)

The English-speaking world measures the height of horses in hands, abbreviated "h" or "hh", for "hands high", measured at the highest point of an animal's withers, where the neck meets the back, chosen as a stable point of the anatomy, unlike the head or neck, which move up and down; one hand is 4 inches (10 cm). Intermediate heights are defined by hands and inches, rounding to the lower measurement in hands, followed by a decimal point and the number of additional inches between 1 and 3. Thus a horse described as "15.2 h", is 15 hands, 2 inches (62 in/160 cm) in height.^[19] The size of horses varies by breed, but can also be influenced by nutrition.

Size varies greatly among horse breeds, as with this full-sized horse and a miniature horse.

The general rule for cutoff in height between what is considered a horse and a pony at maturity is 14.2 hands (58 inches, 147 cm). An animal 14.2 h or over is usually considered to be a horse and one less than 14.2 h a pony.^[20] However, there are exceptions to the general rule. Some breeds which typically produce individuals both under and over 14.2 h are considered horses regardless of their height.^[21] Conversely, some pony breeds may have features in common with horses, and individual animals may occasionally mature at over 14.2 h, but are still considered to be ponies.^[22]

The distinction between a horse and pony is not simply a difference in height, but takes account of other aspects of phenotype or appearance, such as conformation and temperament. 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 often have calmer temperaments than horses and also a high level of equine intelligence that may or may not be used to cooperate with human handlers.^[20] In fact, small size, by itself, is sometimes not a factor at all. While the Shetland pony stands on average 10 hands (40 inches, 102 cm),^[23] the Falabella and other miniature horses, which can be no taller than 30 inches (76 cm), the size of a medium-sized dog, are classified by their respective registries as very small horses rather than as ponies.^[24]

Light riding horses such as Arabians, Morgans, or Quarter Horses usually range in height from 14 to 16 hands (56 to 64 inches, 142 to 163 cm) and can weigh from 385 to 540 kilograms (850 to 1,190 lb). Larger riding horses such as Thoroughbreds, American Saddlebreds or Warmbloods usually start at about 15.2 hands (62 inches, 157 cm) and often are as tall as 17 hands (68 inches, 173 cm), weighing from 500 to 680 kilograms (1,100 to 1,500 lb). Heavy or draft horses such as the Clydesdale, Belgian, Percheron, and Shire are usually at least 16 tp 18 hands (64 to 72 inches, 163 to 183 cm) high and can weigh from about 680 to 900 kilograms (1,500 to 2,000 lb).

The largest horse in recorded history was probably a Shire horse named Mammoth, who was born in 1848. He stood 21.2½ hands high (86.5 in/220 cm), and his peak weight was estimated at 1,500 kilograms (3,300 lb).^[25] The current record holder for the world's smallest horse is Thumbelina, a fully mature miniature horse affected by dwarfism. She is 17 inches (43 cm) tall and weighs 27 kilograms (60 lb).^[26]