Horse

2007 Schools Wikipedia Selection. Related subjects: Mammals

Domestic Horse
Conservation status
Domesticated
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Mammalia Order: Perissodactyla Family: Equidae Genus: Equus Species: E. caballus
Binomial name
Equus caballus Linnaeus, 1758

The horse (Equus caballus, sometimes seen as a subspecies of the Wild Horse, Equus ferus caballus) is a large odd-toed ungulate mammal, one of ten modern species of the genus Equus. Horses have long been among the most economically important domesticated animals; although their importance has declined with mechanization, they are still found worldwide, fitting into human lives in various ways. The horse is prominent in religion, mythology, and art; it has played an important role in transportation, agriculture, and war; it has additionally served as a source of food, fuel, and clothing.

Almost all breeds of horses can, at least in theory, carry humans on their backs or be harnessed to pull objects such as carts or plows. However, horse breeds were developed to allow horses to be specialized for certain task; lighter horses for racing or riding, heavier horses for farming and other tasks requiring pulling power. In some societies, horses are a source of food, both meat and milk; in others it is taboo to consume them. In industrialized countries horses are predominantly kept for leisure and sporting pursuits, while they are still used as working animals in many other parts of the world.

Biology

Age

Depending on breed, management and environment, the domestic horse today has a life expectancy of 25 to 30 years. It is uncommon, but a few horses live into their 40s, and, occasionally, beyond. The oldest verifiable record was "Old Billy," a horse that lived in the 19th century to the age of 62.

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. Most foals are weaned at 4-6 months of age.
• Yearling: a horse of either sex that is between one and two years old.
• Colt: a male horse under the age of four.
• Filly: a female horse under the age of four.
• Mare: a female horse four years old and older.
• Stallion: a non-castrated male horse four years old and older. Some people, particularly in the UK, refer to a stallion as a "horse."
• Gelding: A castrated male horse of any age, 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 or horse may differ from those given above. In the United Kingdom, Thoroughbred horse racing defines a colt as a male horse less than five years old and a filly as a female horse less than five years old. In the USA, both Thoroughbred racing and harness racing defines colts and fillies as four years old and younger.

Size

The size of horses varies by breed, but can also be influenced by nutrition. The general rule for cutoff in height between what is considered a horse and a pony at maturity is 14.2 hands(h or hh) (147 cm, 58 inches) as measured at the withers. An animal 14.2h or over is usually considered a horse and one less than 14.2h is a pony.

However, there are exceptions to the general rule. Some smaller horse breeds who typically produce individual horses both under and over 14.2h are considered "horses" regardless of height. Likewise, some pony breeds, such as the Pony of the Americas or the Welsh cob, share some features of horses and individual animals may occasionally mature at over 14.2h, but are still considered ponies.

The difference between a horse and pony is not simply a height difference, but also a difference in phenotype or appearance. There are noticeable differences in conformation and temperament. Ponies often exhibit thicker manes, tails and overall coat. They also have proportionally shorter legs, wider barrels, heavy bone, thick necks, and short heads with broad foreheads.

Light horses such as Arabians, Morgans, Quarter Horses, Paints and Thoroughbreds usually range in height from 14.0 (142 cm) to 16.0 hands (163 cm) and can weigh from 386 kilograms (850 lbs) to about 680 kg (1500 lbs). Heavy or draft horses such as the Clydesdale, Belgian, Percheron, and Shire are usually at least 16.0 (163 cm) to 18.0 hands (183 cm) high and can weigh from about 682 kg (1500 lb) up to about 900 kg (2000 lb). Ponies are less than 14.2h, but can be much smaller, down to the Shetland pony at around 10 hands, and the Falabella which can be the size of a medium-sized dog. The miniature horse is as small as or smaller than either of the aforementioned ponies but are classified as very small horses rather than ponies despite their size.

The largest horse in history was a Shire horse named Sampson, later renamed Mammoth, foaled in 1846 in Bedfordshire, England. He stood 21.2½ hands high (i.e. 7 ft 2½ in or 2.20 m ), and his peak weight was estimated at over 3,300 lb (approx 1.5 tonnes). The current record holder for the world's smallest horse is Thumbelina, a fully mature miniature horse affected by dwarfism. She is 17 inches tall and weighs 60 pounds.

Reproduction and development

Pregnancy lasts for approximately 335-340 days and usually results in one foal (male: colt, female: filly). Twins are rare. Colts are usually carried 2-7 days longer than fillies. Females 4 years and over are called mares and males are stallions. A castrated male is a gelding. Horses, particularly colts, may sometimes be physically capable of reproduction at approximately 18 months but in practice are rarely allowed to breed until a minimum age of 3 years, especially females. Horses four years old are considered mature, though the skeleton usually finishes developing at the age of six, and the precise time of completion of development also depends on the horse's size (therefore a connection to breed exists), gender, and the quality of care provided by its owner. Also, if the horse is larger, its bones are larger; therefore, not only do the bones take longer to actually form bone tissue (bones are made of cartilage in earlier stages of bone formation), but the epiphyseal plates (plates that fuse a bone into one piece by connecting the bone shaft to the bone ends) are also larger and take longer to convert from cartilage to bone as well. These plates convert after the other parts of the bones do but are crucial to development.

Depending on maturity, breed and the tasks expected, young horses are usually put under saddle and trained to be ridden between the ages of two and four. Although Thoroughbred and American Quarter Horse race horses are put on the track at as young as two years old in some countries (notably the United States), horses specifically bred for sports such as show jumping and dressage are generally not entered into top-level competition until a minimum age of four years old, because their bones and muscles are not solidly developed, nor is their advanced training complete.

Anatomy

Horses have, on average, a skeleton of 205 bones. A significant difference in the bones contained in the horse skeleton, as compared to that of a human, is the lack of a collarbone--their front limb system is attached to the spinal column by a powerful set of muscles, tendons and ligaments that attach the shoulder blade to the torso. The horse's legs and hooves are also unique, interesting 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 the carpal bones that correspond to the human wrist. Similarly, the hock, contains the bones equivalent to those in the human ankle and heel. The lower leg bones of a horse correspond to the bones of the human hand or foot, and the fetlock (incorrectly called the "ankle") is actually the proximal sesamoid bones between the cannon bones (a single equivalent to the human metacarpal or metatarsal bones) and the proximal phalanges, 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 and hair, bone, tendons, ligaments, cartilage, and the assorted specialized tissues that make up the hoof (see section hooves, below).

Digestion

A horse is a herbivore with a digestive system adapted to a forage diet of grasses and other plant material, consumed regularly throughout the day, and so they have a relatively small stomach but very long intestines to facilitate a steady flow of nutrients. A 1000 pound horse will eat between 15 and 25 pounds of food per day and, under normal use, drink 10 to 12 gallons of water. Horses are not ruminants, so they have only one stomach, like humans, but unlike humans, they can also digest cellulose from grasses due to the presence of a "hind gut" called the cecum, or "water gut," that food goes through before reaching the large intestine. Unlike humans, horses cannot vomit, so digestion problems can quickly spell trouble, with colic a leading cause of death.

Teeth

Horses are adapted to grazing, so their teeth continue to grow throughout life. There are 12 teeth (six upper and six lower), the incisors, adapted to biting off the grass or other vegetation, at the front of the mouth, and 24 teeth, the premolar and molars, adapted for chewing, at the back of the mouth. Stallions and geldings have four additional teeth just behind the incisors, a type of canine teeth that are called "tushes." Some horses, both male and female, will also develop one to four very small vestigial teeth in front of the molars, known as "wolf" teeth, which are generally removed because they can interfere with the bit.

There is an empty interdental space between the incisors and the molars where the bit rests directly on the bars (gums) of the horse's mouth when the horse is bridled.

The incisors show a distinct wear and growth pattern as the horse ages, as well as change in the angle at which the chewing surfaces meet, and while the diet and veterinary care of the horse can affect the rate of tooth wear, a very rough estimate of the age of a horse can be made by looking at its teeth.

Hooves

The critical importance of the feet and legs is summed up by the traditional adage, "no foot, no horse." The horse hoof begins with the distal phalanges, the equivalent of the human fingertip or tip of the toe, surrounded by cartilage and other specialized, blood-rich soft tissues such as the laminae, with the exterior hoof wall and horn of the sole made essentially of the same material as a human fingernail. The end result is that a horse, weighing on average 1,000 pounds, travels on the same bones as a human on tiptoe. For the protection of the hoof under certain conditions, some horses have horseshoes placed on their feet by a professional farrier. The hoof continually grows, just like a large fingernail, and needs to be trimmed (and horseshoes reset, if used) every six to eight weeks.

Senses

The senses of a horse are generally superior to those of a human. As prey animals, they must be aware of their surroundings at all times. They have very large eyes (among land animals only the ostrich has a larger eye), with excellent day and night vision, though they may have a limited range of colour vision. The side positioning of the eyes gives the horse a wide field of vision of about 350°. While not colour-blind, studies indicate that they have difficulty distinguishing greens, browns and grays. Their hearing is good, and the pinna of their ears can rotate a full 360 degrees in order to pick up sound from any direction. Their sense of smell, while much better than that of humans, is not their strongest asset; they rely to a greater extent on vision.

A horse's sense of balance is outstanding; the cerebellum of their brain is highly developed and they are very aware of terrain and placement of their feet. Horses' sense of touch is better developed than many people think; they immediately notice when a fly or mosquito lands on them, even before the insect attempts to bite. Their sense of taste is well-developed in order to determine the nature of the plants they are eating, and their prehensile lips can easily sort even the smallest grains. Horses will seldom eat most poisonous plants or spoiled food unless they have no other choices, although a few toxic plants have a chemical structure that appeals to animals, and thus poses a greater risk of being ingested.

Behaviour

Horses are prey animals with a well-developed fight-or-flight instinct. Their first response to threat is to flee, although they are known to stand their ground and defend themselves or their offspring in cases where flight is not possible, such as when a foal would be threatened. Through selective breeding, some breeds of horses have been bred to be quite docile, particularly certain large draft horses. However, most light horse riding breeds were developed for speed, agility, alertness and endurance; natural qualities that extend from their wild ancestors.

Horses are herd animals, with a clear hierarchy of rank, led by a dominant animal (usually a mare). Horses are also social creatures who 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. Many horses will become flighty and hard to manage if they are isolated. When this behaviour occurs while being handled by human, the horse is called being "herd-bound". However, through proper training, it is possible to teach any horse to be comfortable away from the herd.

When confined with insufficient companionship, exercise or stimulation, horses may develop stable vices, an assortment of bad habits, mostly psychological in origin, that include wood chewing, wall kicking, "weaving" (rocking back and forth) and other problems.

Sleep patterns

Horses are able to sleep both standing up and lying down. They are able to doze and enter light sleep while standing, an adaptation from life as a prey animal in the wild. Lying down makes an animal more vulnerable to predators. Horses are able to sleep standing up because a "stay apparatus" in their legs allows them to relax their muscles and doze without collapsing.

Unlike humans, horses do not need a solid, unbroken period of sleep time. They obtain needed sleep by means of many short periods of rest. Horses may spend anywhere from four to fifteen hours a day in standing rest, and from a few minutes to several hours lying down. However, not all this time is the horse actually asleep; total sleep time in a day may range from several minutes to a couple of hours. Horses require approximately two and a half hours of sleep, on average, in a 24-hour period. Most of this sleep occurs in many short intervals of about 15 minutes each.

Horses must lie down to reach REM sleep. 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, though horses may also suffer from that disorder.

Horses sleep better when in groups because some animals will sleep while others stand guard to watch for predators. A horse kept entirely alone will not sleep well because its instincts are to keep a constant eye out for danger.

Gaits

All horses move naturally with four basic gaits; the walk, trot or jog, canter or lope, and gallop.

Besides these basic gaits, there are many additional "ambling" or "single-foot" gaits such as pace, slow gait, rack, fox trot running walk, and tölt. These special gaits are often found in specific breeds, often referred to as "gaited" horses because they naturally possess additional gaits that are approximately the same speed as the trot but smoother to ride. Technically speaking the so called "gaited horses" replace the standard trot which is a 2 beat gait with a four beat gait (as opposed to the canter/lope and gallop which are three beat gaits).

Horse breeds with additional gaits that often occur naturally include the Tennessee Walking Horse which naturally performs a running walk, the American Saddlebred which can easily be trained to exhibit a slow gait and the rack, the Paso Fino horse with the paso corto and paso largo, and Icelandic horses which are known for the tölt. The fox trot is found in several breeds, most notably the Missouri Foxtrotter. Standardbreds, depending on bloodlines and training, may either pace or trot.

Horse Care

Horses are animals that evolved to graze. Therefore, they eat grass or hay, sometimes supplemented with grain. Although horses are adapted to live outside, they require shelter from the wind and rain. Horses require annual vaccinations to protect against various diseases, need routine hoof care by a farrier, and regular dental examinations from a veterinarian 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.

Evolution

The horse as it is known today adapted by evolution to survive in areas of wide-open terrain with sparse vegetation, surviving in an ecosystem where other large grazing animals, especially ruminants, could not.

Horses and other equids are odd-toed ungulates of the order Perissodactyla, a relatively ancient group of browsing and grazing animals that first arose less than 10 million years after the dinosaurs became extinct. In the past, this order contained twelve families, but only three families— Equidae (the horse and related species), the tapir and the rhinoceros—have survived to the present day. The earliest equids known as Hyracotherium developed approximately 54 million years ago, during the Eocene period. One of the first true horse species, it had 4 toes on each front foot, and 3 toes on each back foot. By the Pleistocene era, as the horse adapted to a drier, prairie environment, the 2nd and 4th toes disappeared on all feet, and horses became bigger. These side toes first shrunk in size until they have vanished in modern horses. All that remains are a set of small vestigial bones on either side of the cannon ( metacarpal or metatarsal) bone, known informally as splint bones, which are a frequent source of splints, a common injury in the modern horse. Their legs also lengthened as their toes disappeared and until they were a hoofed animal capable of running at great speed.

Over millions of years, equid teeth also evolved from browsing on soft, tropical plants to adapt to browsing of drier plant material, and grazing of tougher plains grasses. Thus the 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. For reasons not fully understood, Equus caballus disappeared from North America around 10,000 years ago, at the end of the last Ice Age.

Domestication and surviving wild species

Competing theories exist as to the time and place of initial domestication. The earliest evidence for the domestication of the horse comes from Central Asia and dates to approximately 4,500 BC. Archaeological finds such as the Sintashta chariot burials provided unequivocal evidence that the horse was definitely domesticated by 2000 BC.

Wild prototypes and modern species

Most "wild" horses today are actually feral horses (see feral horses, below), animals that had domesticated ancestors but were themselves born and live in the wild, often for generations. However, there are also some truly wild horses whose ancestors were never successfully domesticated.

The "Four Foundations" theory

There is a theory that there were four basic "proto" horses that developed with adaptations to their environment prior to domestication. There are competing theories, some arguing that the prototypes were separate species, others suggesting that the prototypes were physically different manifestations of the same species. Either way, the most common theories of historical wild species from which other types are thought to have developed suggests the following base prototypes:

• The "Warmblood subspecies" or "Forest Horse" (Equus ferus silvaticus, also called the Diluvial Horse), thought to have evolved into Equus ferus germanicus, and which may have contributed to the development of the warmblood horses of northern Europe, as well as older "heavy horses" such as the Ardennais.
• The "Draft" subspecies, a small, sturdy, heavyset animal with a heavy hair coat, arising in northern Europe, adapted to cold, damp climates, somewhat resembling today's draft horse and even the Shetland pony
• The "Oriental" subspecies, a taller, slim, refined and agile animal arising in western Asia, adapted to hot, dry climates, thought to be the progenitor of the modern Arabian horse and Akhal-Teke
• The "Tarpan subspecies," dun-colored, sturdy animal, the size of a large pony, adapted to the cold, dry climates of northern Asia, the predecessor to the Tarpan and Przewalski's Horse as well as the domesticated Mongolian horse.

Species surviving into modern times

The tarpan, Equus ferus ferus, survived into the historical era, but became extinct in 1880. Its genetic line is lost, but its phenotype has been recreated by a " breeding back" process, in which living domesticated horses with primitive features were repeatedly interbred. Thanks to the efforts of the brothers Lutz Heck (director of the Berlin zoo) and Heinz Heck (director of Munich Tierpark Hellabrunn), the resulting Heck horse together with the Konik resembles the tarpan more closely than any other living horse.

Przewalski's Horse (Equus ferus przewalskii), a rare Asian species, is the only true wild horse alive today. Also known as the Mongolian Wild Horse, Mongolians know it as the taki, while the Kirghiz people call it a kirtag. Small wild breeding populations of this animal, named after the Russian explorer Przewalski, exist in Mongolia. There are also small populations maintained at zoos throughout the world. After a battle against extinction, the Przewalksi's Horse is finally flourishing in the wild once again.

Other truly wild equids alive today include the zebra and the onager.

Feral horses

Feral animals, who had domesticated ancestors but were born and live in the wild, are distinct from wild animals, whose ancestors have never undergone domestication. Several populations of feral horses exist, including those in the western United States and Canada (often called " mustangs"), and in parts of Australia (" brumbies") and New Zealand (" Kaimanawa horses"). Isolated feral populations are often named for their geographic location: Namibia has its Namib Desert Horses; the Sorraia lives in Spain and Portugal; Sable Island Horses reside in Nova Scotia, Canada; and New Forest ponies have been part of Hampshire, England for a thousand years.

Studies of feral horses have provided useful insights into the behaviour of ancestral wild horses, as well as greater understanding of the instincts and behaviours that drive horses.

Other modern equids

Other members of the horse family include zebras, donkeys, and onagers. The Donkey, Burro or Domestic Ass, Equus asinus, like the horse, has many breeds. A mule is a hybrid of a male ass (jack) and a mare, and is usually infertile. A hinny is the less common hybrid of a female ass (jenny) and a stallion. Breeders have also tried crossing various species of zebra with mares or female asses to produce "zebra mules" ( zorses, and zonkeys (also called zedonks)). This will probably remain a novelty hybrid as these individuals tend to inherit some of the undomesticated nature of their zebra parent, but they may inherit the zebra's resistance to nagana pest: zorses, also called zebroids, have been used in Central African game parks for light haulage.

Horses within the human economy

Around the world, horses play a role within human economies, for leisure, sport and working purposes. To cite one example, 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 wealthier, First World, industrialized economies, horses are primarily used in recreational pursuits and competitive sports, though they also have practical uses in police work, cattle ranching, search and rescue, and other duties where terrain or conditions preclude use of motorized vehicles. In poorer, Third World economies, they may also be used for recreational purposes by the elite population, but serve a much wider role in working pursuits including farming, ranching and as a means of transportation. To a very limited extent, they are also still used in warfare, particularly in regions of extremely rugged terrain.

Sport

Horses are trained to be ridden or driven in many different sporting events and competitions. Examples include horse shows, gymkhana and O-Mok-See, rodeos, endurance riding, fox hunting, and Olympic-level events such as three-day eventing, combined driving, dressage, and show jumping. Although scoring varies by event, most emphasize the horse's speed, maneuverability, obedience and/or precision. Sometimes the equitation, the style and ability of the rider, is also considered.

Sports such as polo and horseball 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 assists this process and requires specialized training to do so, 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 achievement. Examples of these sports of partnership between human and animal also include jousting (reenacting the skills used by medieval knights), where the main goal is for one rider to dismount the other, and buzkashi, a team game played throughout Central Asia, the aim being to capture a goat carcass while on horseback.

The most widely known use of horses for sport is horse racing, seen in almost every nation in the world. There are three types: "flat" racing; steeplechasing, i.e. racing over jumps; and harness racing, where horses trot or pace while pulling a driver in a small, light cart known as a sulky. Most race horses in the developed world are Thoroughbreds, a breed which can reach speeds up to 40 mph/70 km/h. In the case of a specialized sprinting breed, the American Quarter Horse, speeds over 50 mph have been clocked. In harness racing, performed by Standardbred horses, speeds over 30 mph have been measured. A major part of the economic importance of horse racing, as for many sports, lies in the gambling associated with it.

Work

There are certain jobs that horses do very well, and no amount of technology appears able to supersede. Mounted police horses are still effective for 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 teams to locate people, particularly hikers and hunters, who are lost in remote areas.

Some land management practices such as logging can be more efficiently managed with horses, to avoid vehicular disruption to delicate soil in areas such as a nature reserve. Forestry rangers may use horses for their patrols.

In poor countries such as Romania, Kyrgyzstan, and many parts of the Third World, horses, donkeys and mules are routinely used for transport and agriculture. In areas where roads are poor or non-existent and fossil fuels are scarce or the terrain rugged, riding horseback is still the most efficient way to get from place to place.

Entertainment and culture

Modern horses are often used to re-enact their historical work purpose. One famous example is the Budweiser Clydesdales. This team of draft horses pull a beer wagon in a manner similar to that used prior to the invention of the modern motorized truck.

Horses are used, complete with equipment that is authentic or a meticulously recreated replica, in various historical reenactments of specific periods of history, and especially famous battles. Popular subjects include American Revolutionary War and Civil War reenactments, as well as battles of the 19th century between the U.S. Cavalry and Native Americans, such as the Battle of the Little Bighorn.

Horses also are used preserve cultural traditions and for ceremonial purposes. Examples include the use of horses at tourist destinations such as Colonial Williamsburg or the presence of cavalry horses at significant funerals of military figures and heads of state. Countries such as the United Kingdom still use horse-drawn carriages to convey royalty and VIPs to and from certain culturally significant events.

Horses are frequently used in television and motion pictures to add authenticity to historical dramas as well as adding charm to films set in modern-day, or even futuristic science fiction settings.

Assisted learning and therapeutic purposes

People with disabilities obtain beneficial results from association with horses. The movement of a horse strengthens muscles throughout a rider's body and promotes better overall health. In many cases, riding has also led to increased mobility for the rider. Horses also provide psychological benefits to people whether they actually ride or not. 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 FEI.

Hippotherapy and therapeutic horseback riding are names for different physical, occupational and speech therapy treatment strategies that utilize equine movement. In the hippotherapy environment, a therapist uses the horse's movement to provide carefully graded sensory input, whereas therapeutic horseback riding uses specific riding skills.

"Equine-assisted" or "equine-facilitated" psychotherapy uses horses as companion animals to assist people with psychological problems. Actual practices vary widely due to the newness of the field; some programs include Therapeutic Horseback Riding and hippotherapy. Non-riding therapies simply encourage a person to touch, speak to and otherwise interact with the horse. People appear to benefit from being able to be around a horse; horses are very sensitive to non-verbal communication and are an ideal resource for working with individuals who have "tuned out" human therapists.

Equine Assisted Learning (EAL), Equine guided education, or equine assisted professional development, is another relatively new field of experiential learning for corporate, professional and personal development.

There also have been experimental programs using horses in prison settings. Exposure to horses appears to improve the behaviour of inmates in a prison setting and help reduce recidivism when they leave. A correctional facility in Nevada has a successful program where inmates learn to train young mustangs captured off the range in order to make it more likely that these horses will find adoptive homes. Both adult and juvenile prisons in New York, Florida, and Kentucky work in cooperation with the Thoroughbred Retirement Foundation to re-train former racehorses as pleasure mounts and find them new homes. Horses are also used in camps and programs for young people with emotional difficulties.

Warfare

Horses in warfare have been seen for most of recorded history, dating back at least to the 19th century B.C. While mechanization largely has 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 Darfur conflict in attacks against unarmed civilians.

Products

• Horse meat has been used as food for animals and humans throughout the ages. It is eaten in many parts of the world and is an export industry in the United States and other countries. Bills have been introduced in both the House and the Senate which would put an end to this practice in the United States. Horse consumption is taboo in some cultures.

• Mare's milk is used by people with large horse-herds, such as the Mongols. They may let it ferment to produce kumis. Mares produce a lower yield of milk than cows, but more than goats and sheep.

• Horse blood was also used as food by the Mongols and other nomadic tribes. The Mongols found this food source especially convenient when riding for long periods of time. Drinking their own horse's blood allowed the Mongols to ride for extended periods of time without stopping to eat.

• Premarin is a mixture of female hormones ( estrogens) extracted from the urine of pregnant mares (pregnant mares' urine). It is a widely used drug for hormone replacement therapy. This horse product is especially controversial; see the Premarin article.

• The tail hair of the horse is used for making bows for stringed instruments such as the violin, viola, cello and double bass.

• Horsehide leather has been used for boots, gloves, jackets, baseballs, and baseball gloves. The saba is a horsehide vessel used in the production of kumis. Horsehide can be used to produce animal glue.

• Horse hooves can be used to produce hoof 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.

Specialized vocabulary

Because horses and humans have lived and worked together for thousands of years, an extensive specialized vocabulary has arisen to describe virtually every horse behavioural and anatomical characteristic with a high degree of precision.

The anatomy of the horse comes with a large number of horse specific terms.

Horses exhibit a diverse array of coat colors and distinctive markings, and a specialized vocabulary has evolved to describe them. Often, one will refer to a horse in the field by its coat colour rather than by breed or by sex. The genetics of the coat colors has largely been resolved, although discussion continues about some of the details.

The English-speaking world measures the height of horses in hands, abbreviated "h" or "hh," and is measured at the highest point of an animal's withers. One hand is 4 Imperial inches, or, as defined in British law, 101.6 mm. 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 hh tall, means it is 15 hands, 2 inches, or 62 inches/1.57 m in height.

The origin of modern breeds

Horses come in various sizes and shapes. The draft breeds can top 19 hands (2 metres, 76 inches) while the smallest miniature horses stand as low as 5.2 hands (0.56 metres, 22 inches). The Patagonian Fallabella, usually considered the smallest horse in the world, compares in size to a German Shepherd Dog.

Different schools of thought exist to explain how this range of size and shape came about. One school, which some refer to as the "Four Foundations", (see Domestication of the horse and surviving wild species, above), suggests that the modern horse evolved from multiple types of early wild pony and horse prototypes; the differences between these types account for the differences in type of the modern breeds. A second school - the "Single Foundation" - holds only one type of wild horse underwent domestication, and it diverged in form after domestication through human selective breeding (or in the case of feral horses, through ecological pressures). This question will most likely only be resolved once geneticists have finished evaluating the horse genome, analyzing DNA and mitochondrial DNA to construct family trees. See: Domestication of the horse.

In either case, modern horse breeds developed in response to the need for "form to function"; that is, the necessity to develop certain physical characteristics necessary to perform a certain type of work. Thus, light, refined horses such as the Arabian horse or the Akhal-Teke developed in dry climates to be fast and with great endurance over long distances, while heavy draft horse such as the Belgian developed out of a need to pull plows and perform other farm work. Ponies of all breeds developed out of a dual need to create mounts suitable for children as well as for work in small places like mine shafts or in areas where there was insufficient forage to support larger draft animals. In between these extremes, horses were bred to be particularly suitable for tasks that included pulling carriages, carrying heavily-armored knights, jumping, racing, herding other animals, and packing supplies.

Some countries specialize in breeding horses suitable for particular activities. For example, Australia, the United States, and the Patagonia region of South America are known for breeding horses particularly suitable for working cattle and other livestock. Germany produces many Warmblood breeds that are used for dressage. Ireland is recognized for breeding hunters and jumpers. Spain and Portugal are known for the Iberian horse breeds used in high school dressage and bullfighting. Austria is known worldwide for its Lipizzaner horses, used for dressage and high school work in the famous Spanish Riding School in Vienna. The United Kingdom breeds an array of heavy draft horses and several breeds of hardy ponies. Both the United States and Great Britain are noted for breeding Thoroughbred race horses. Russia takes great pride in breeding harness racing horses, a tradition dating back to the development of the Orlov Trotter in the 18th century.

Breeds, studbooks, purebreds, and landraces

Selective breeding of horses has occurred as long as humans have domesticated them. However, the concept of controlled breed registries has gained much wider importance during the 20th century. One of the earliest formal registries was General Stud Book for thoroughbreds, a process that started in 1791 tracing back to the foundation sires for that breed. These sires were Arabians, brought to England from the Middle East.

The Arabs had a reputation for breeding their prize Arabian mares to only the most worthy stallions, and kept extensive pedigrees of their " asil" (purebred) horses. Though these pedigrees were primarily transmitted via an oral tradition, written pedigrees of Arabian horses can be found that date to the 14th century. During the late Middle Ages the Carthusian monks of southern Spain, themselves forbidden to ride, bred horses which nobles throughout Europe prized; the lineage survives to this day in the Andalusian horse or caballo de pura raza espanol.

The modern landscape of breed designation presents a complicated picture. Some breeds have closed studbooks; a registered Thoroughbred, Arabian, or Quarter Horse must have two registered parents of the same breed, and no other criteria for registration apply. Other breeds tolerate limited infusions from other breeds; for example, the modern Appaloosa must have at least one Appaloosa parent but may also have a Quarter Horse, Thoroughbred, or Arabian parent and must also exhibit spotted coloration to gain full registration. Still other breeds, such as most of the warmblood sport horses, require individual judging of an individual animal's quality before registration or breeding approval, but also allow outside bloodlines in if the horses meet the standard.

Breed registries also differ as to their acceptance or rejection of breeding technology. For example, all Jockey Club Thoroughbred registries require that a registered Thoroughbred be a product of a natural mating (live cover in horse parlance). A foal born of two Thoroughbred parents, but by means of artificial insemination or embryo transfer is barred from the Thoroughbred studbook. Any Thoroughbred bred outside of these constraints can, however, become part of the Performance Horse Registry.

On the other hand, since the advent of DNA testing to verify parentage, most breed registries now allow artificial insemination (AI), embryo transfer (ET), or both. The high value of stallions has helped with the acceptance of these techniques because they 1) allow a stallion to breed more mares with each "collection," and 2) take away the risk of injury during mating.

Hot bloods, warm bloods, and cold bloods

Horses are mammals and as such are all warm-blooded creatures, as opposed to reptiles, which are cold-blooded. However, these words have developed a separate meaning in the context of equine description, with the "hot-bloods", such as race horses, exhibiting more sensitivity and energy, while the "cold-bloods" are heavier, calmer creatures such as the draft giants.

Hot bloods

Arabian horses, whether originating on the Arabian peninsula or from the European studs (breeding establishments) of the 18th and 19th centuries, gained the title of "hot bloods" for their temperament, characterized by sensitivity, keen awareness, athleticism, and energy. European breeders wished to infuse some of this energy and athleticism into their own best cavalry horses. These traits, combined with the lighter, aesthetically refined bone structure of the oriental-type horse ( Akhal-Teke, Arabian, Barb), were used as the foundation of the thoroughbred breed.

True hot bloods usually offer both greater riding challenges and rewards than other horses. Their sensitivity and intelligence enable quick learning with greater communication and cooperation with their riders. However, their intelligence also allows them to learn bad habits as quickly as good ones. Because of this, they also can quickly lose trust in a poor rider and do not tolerate inept or abusive training practices.

Cold bloods

Muscular and heavy draft horses are known as "cold bloods", as they have been bred to have the calm, steady, patient temperament needed to pull a plow or a heavy carriage full of people. One of the best-known draft breeds is the Belgian. The largest is the Shire. The Clydesdales, with their common coloration of a bay or black coat with white legs and long-haired, "feathered" fetlocks are among the most easily recognized.

Warmbloods

" Warmblood" breeds began when the European carriage and war horses were crossed with oriental horses or thoroughbreds. The term " warm blood" was originally used to mean any cross of heavy horses on Thoroughbred or Arabian horses. Examples included breeds such as the Irish Draught horse, and sometimes also referred to the "Baroque" horses used for "high school" dressage, such as the Lipizzaner, Andalusian, Lusitano and the Alter Real. Sometimes the term was even used to refer to breeds of light riding horse other than Thoroughbreds or Arabians, such as the Morgan horse. But today the term "warmblood" usually refers to a group of sport horse breeds that have dominated the Olympic Games and World Equestrian Games in Dressage and Show Jumping since the 1950s. These breeds include the Hanoverian, Oldenburg, Trakehner, Holsteiner, Swedish Warmblood, and Dutch Warmblood.

The list of horse breeds provides a partial alphabetical list of breeds of horse extant today, plus a discussion of rare breeds' conservation.

Riding methods

Saddling and mounting

The common European practice and tradition of saddling and mounting the horse from the left hand side is widely believed to originate from the practice of right-handed fighters carrying their sheathed sword on their left hip, making it easier to throw their right leg over the horse when mounting. However, several other explanations are equally also plausible.

Horses can be mounted bareback with a vault from the ground, by grabbing the mane to provide leverage as a rider makes a small jump and scrambles up onto the horse's back (an awkward but popular method used by children), or by "bellying over", a technique which involves placing both hands side by side on the horse's back, jumping up so that the rider lays belly down on the horse's back, and swinging the leg over to sit astride. In actual practice, however, most bareback riders use a fence, mounting block, or other object which can be stood upon to be able to simply slide onto the horse's back. This method is more convenient for both horse and rider, as the horse is more comfortable not being accidentally jabbed by the legs and arms of the rider, and any method of mounting without a saddle can be difficult for the rider, especially if the horse is tall.

Control of the horse

Riders communicate with the horse through commands called aids. The main natural aids of the rider are the legs, the seat, the hands (through the reins) and the voice (used less often than other aids). The rider's legs generally tell the horse to move forward or to turn. The hands help to guide the horse in the direction of the turn, and ask the horse to either slow his tempo or to slow from a faster gait to a slower one. The seat is the most difficult aid to develop, and can communicate to the horse not only to speed up, but also to turn and slow down.

Correct position allows for the rider to communicate effectively without getting in the way of the horse. Additionally, the position is slightly modified according to the type of riding that is being preformed. Like most arts, riding takes years of practice to become competent, as the riders work to refine their aids and position, and learn "feel" (or what the horse is doing underneath them).

Types of riding

Since the horse was domesticated, a wide variety of riding methods or styles have developed, all of which balance the need to allow the horse freedom of movement in activities such as horse racing or show jumping and the need for security of the rider, precision of commands and overall control as seen in activities such as dressage and reining. Worldwide, the most common modern riding style is referred to as English riding, which is a broad style that encompasses most Olympic Equestrian competition, and includes such specific styles as dressage, hunt seat, show jumping and saddle seat, among many others. Western riding is a popular style seen in North America, derived from the traditions of Spain, modified to fit the needs of cattle ranchers. A similar riding style is seen with the Stockman of Australia.