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Pregnant mare grazing Jument boulonnaise alezan crins laves, Samer.jpg
Pregnant mare grazing

A mare is an adult female horse or other equine. [1]


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 years old. The word can also be used for other female equine animals, particularly mules and zebras, but a female donkey is usually called a "jenny". A broodmare is a mare used for breeding. A horse's female parent is known as its dam.

An uncastrated adult male horse is called a stallion and a castrated male is a gelding. Occasionally, the term "horse" is used to designate only a male horse.

Reproductive cycle

A nursing foal. Domesticated mares may nurse their foals an average of four to six months, occasionally longer, depending on human management decisions and the temperament of a given mare. Poulain ardennais 02.jpg
A nursing foal. Domesticated mares may nurse their foals an average of four to six months, occasionally longer, depending on human management decisions and the temperament of a given mare.
Reproductive organs of the mare. (superior view) The anatomy of the horse - a dissection guide (1922) (18008737319).jpg
Reproductive organs of the mare. (superior view)

Mares carry their young (called foals) for approximately 11 months from conception to birth. (Average range 320–370 days.) [2] Usually just one young is born; twins are rare. When a domesticated mare foals, she nurses the foal for at least four to six months before it is weaned, though mares in the wild may allow a foal to nurse for up to a year.

The estrous cycle, also known as "season" or "heat" of a mare occurs roughly every 19–22 days and occurs from early spring into autumn. As the days shorten, most mares enter an anestrus period during the winter and thus do not cycle in this period. The reproductive cycle in a mare is controlled by the photoperiod (length of the day), the cycle first triggered when the days begin to lengthen. As the days shorten, the mare returns to the anestrus period when she is not sexually receptive. Anestrus prevents the mare from conceiving in the winter months, as that would result in her foaling during the harshest part of the year, a time when it would be most difficult for the foal to survive. [3]

However, for most competitive purposes, foals are given an official "birthday" of January 1 (August 1 in the Southern hemisphere), and many breeders want foals to be born as early in the year as possible. Therefore, many breeding farms begin to put mares "under lights" in late winter in order to bring them out of anestrus early and allow conception to occur in February or March. One exception to this general rule is the field of endurance riding, which requires horses to be 60 true calendar months old (5 years) before competing at longer distances.

Fillies are sexually mature by age two and are sometimes bred at that age, but generally should not be bred until they have stopped growing, usually by age four or five. [4]

A healthy, well-managed mare can produce a foal every year into her twenties, though not all breeders will breed a mare every year. In addition, many mares are kept for riding and so are not bred annually, as a mare in late pregnancy or nursing a foal is not able to perform at as athletic a standard as one who is neither pregnant nor lactating. In addition, some mares become anxious when separated from their foals, even temporarily, and thus are difficult to manage under saddle until their foals are weaned.

Illustration of a cross-section of a pregnant mare The new book of the horse (Pl. 27) (8536503249).jpg
Illustration of a cross-section of a pregnant mare


A broodmare. Note slight distension of belly, indicating either early pregnancy or recent foaling. Lovely Little Girl.jpg
A broodmare. Note slight distension of belly, indicating either early pregnancy or recent foaling.

Mares are considered easier to handle than stallions. However, geldings have little to no hormone-driven behavior patterns at all, thus sometimes they are preferred to both mares and stallions. Mares have a notorious, if generally undeserved, reputation for being "marish", meaning that they can be cranky or unwilling when they come into season.[ citation needed ]

While a few mares may be somewhat more distractible or irritable when in heat, they are far less easily distracted than a stallion at any time. Solid training usually minimizes hormonal behavior. For competitive purposes, mares are sometimes placed on hormone therapies, such as the drug Regumate, to help control hormonally based behavior. Some riders also use various herbal remedies, most of which have not been extensively tested for effectiveness.

In relation to maternal behaviour, the formation of the bond between a mare and her foal "occurs during the first few hours post-partum, but that of the foal to the mare takes place over a period of days". [5]

Mares and geldings can be pastured together. However, mares may be a bit more territorial than geldings, even though they are far less territorial than stallions. Sex-segregating herds may make for less infighting, especially if kept in close quarters. However, studies also have shown that when a "lead mare" or "boss mare" is in charge of a herd, all remaining animals rest for longer periods and seem more at ease than do those in herds led by a gelding.

In wild herds, a "boss mare" or "lead mare" leads the band to grazing, to water, and away from danger. She eats and drinks first, decides when the herd will move and to where. The herd stallion usually brings up the rear and acts as a defender of the herd against predators and other stallions.


Mares can be used in any equestrian sport and have competed successfully against males. Zenyatta, winner of the 2009 Breeders' Cup Classic, racing in the Lady's Secret Stakes. Zenyatta2009LadySecret.jpg
Mares can be used in any equestrian sport and have competed successfully against males. Zenyatta, winner of the 2009 Breeders' Cup Classic, racing in the Lady's Secret Stakes.

Mares are used in every equestrian sport and usually compete equally with stallions and geldings in most events, though some competitions may offer classes open only to one sex of horse or another, particularly in breeding or "in-hand" conformation classes. In horse racing, mares and fillies have their own races and only a small percentage compete against male horses. However, a few fillies and mares have won classic horse races against colts, including the Prix de l'Arc de Triomphe, the Kentucky Derby, the Preakness Stakes, the Belmont Stakes, the Melbourne Cup and the Breeders' Cup Classic.

Mares are used as dairy animals in some cultures, especially by the nomads and formerly nomadic peoples of Central Asia. Fermented mare's milk, known as kumis, is the national drink of Kyrgyzstan. Some mares, usually of draft horse breeding, are kept in North America for the production of their urine. Pregnant mares' urine is the source of the active ingredient in the hormonal drug Premarin (derived from Pregnant mares' urine).

Historic use

Until the invention of castration, and even later where there was less cultural acceptance of castration, mares were less difficult to manage than stallions and thus preferred for most ordinary work. Historically, the Bedouin nomads of the Arabian peninsula preferred mares on their raids, because stallions would nicker to the opposing camps' horses, whereas mares would be quiet. However, other cultures preferred male horses over mares either due to a desire for more aggressive behavior in a fighting animal, or to not be inconvenienced with a loss of work ability due to a mare's pregnancy, parturition and lactation.


The word mare, meaning "female horse", took several forms before A.D. 900. [6] In Old English the form was mīere, mere or mȳre, the feminine forms for mearh (horse). The Old German form of the word was Mähre. [7] Similarly, in Irish and Gaelic, the word was marc, in Welsh, march, in Cornish "margh", and in Breton marc'h. [7] The word is "said to be of Gaulish origin." [7] It is said by some writers to derive from Proto-Germanic *marhijō (“female horse”), from Proto-Germanic marhaz ("horse"), from Proto-Indo-European *markos ("horse"). [8] [9] The word has no known cognates beyond Germanic and Celtic. [7] One possible derived term is a mare's nest, an expression for "excitement over something which does not exist". [7] The term nightmare , is not directly connected etymologically with the word for female horse, but rather to homophones that meant "incubus" or "goblin". [7]

See also

Related Research Articles

Horse Domesticated four-footed mammal from the equine family

The horse is one of two extant subspecies of Equus ferus. It is an odd-toed ungulate mammal belonging to the taxonomic family Equidae. The horse has evolved over the past 45 to 55 million years from a small multi-toed creature, Eohippus, into the large, single-toed animal of today. Humans began domesticating horses around 4000 BC, and their domestication is believed to have been widespread by 3000 BC. Horses in the subspecies caballus are domesticated, although some domesticated populations live in the wild as feral horses. These feral populations are not true wild horses, as this term is used to describe horses that have never been domesticated, such as the endangered Przewalski's horse, a separate subspecies, and the only remaining true wild horse. 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.

A horse breed is a selectively bred population of domesticated horses, often with pedigrees recorded in a breed registry. However, the term is sometimes used in a broader sense to define landrace animals of a common phenotype located within a limited geographic region, or even feral “breeds” that are naturally selected. Depending on definition, hundreds of "breeds" exist today, developed for many different uses. 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.

Horse breeding

Horse breeding is reproduction in horses, and particularly the human-directed process of selective breeding of animals, particularly purebred horses of a given breed. Planned matings can be used to produce specifically desired characteristics in domesticated horses. Furthermore, modern breeding management and technologies can increase the rate of conception, a healthy pregnancy, and successful foaling.

Mule Offspring of a male donkey (jack) and a female horse (mare)

A mule is the offspring of a male donkey (jack) and a female horse (mare). Horses and donkeys are different species, with different numbers of chromosomes. Of the two first-generation hybrids between these two species, a mule is easier to obtain than a hinny, which is the offspring of a female donkey (jenny) and a male horse (stallion).

Gelding Castrated horse or other male equine

A gelding is a castrated 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 horse to be calmer and better-behaved, making the animal quieter, gentler and potentially more suitable as an everyday working animal. The gerund and participle "gelding" and the infinitive "to geld" refer to the castration procedure itself.

A bachelor herd is a herd of (usually) juvenile male animals who are still sexually immature or 'harem'-forming animals who have been thrown out of their parent groups but not yet formed a new family group. It may also refer to a group of males who are not currently territorial or mating with females.


A filly is a female horse that is too young to be called a mare. There are two specific definitions in use:

Foal A horse of either sex up to the age of one year

A foal is an equine up to one year old; this term is used mainly for horses. 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 is nursing from its great (mother), it may also be called a "suckling". After it has been weaned from its dam, it may be called a "weanling". When a mare is pregnant, she is said to be "in foal". When the mare gives birth, she is "foaling", and the impending birth is usually stated as "to foal". A newborn horse is "foaled".


The Holsteiner is a breed of horse originating in the Schleswig-Holstein region of northern Germany. It is thought to be the oldest of warmblood breeds, tracing back to the 13th century. Though the population is not large, Holsteiners are a dominant force of international show jumping, and are found at the top levels of dressage, combined driving, show hunters, and eventing.

The estrous cycle or oestrous cycle 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 phases or by pregnancies. Typically, estrous cycles continue until death. Some animals may display bloody vaginal discharge, often mistaken for menstruation.

A colt is a male horse, usually below the age of four years.

Stud (animal)

A stud animal is a registered animal retained for breeding. The terms for the male of a given animal species usually imply that the animal is intact—that is, not castrated—and therefore capable of siring offspring. A specialized vocabulary exists for de-sexed animals and those animals used in grading up to a purebred status.

Stallion male horse that has not been castrated

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" neck, as well as a somewhat more muscular physique as compared to female horses, known as mares, and castrated males, called geldings.

Horse behavior

Horse behavior is best understood from the view that horses are prey animals with a well-developed fight-or-flight response. Their first reaction to a threat is often to flee, although sometimes they stand their ground and defend themselves or their offspring in cases where flight is untenable, such as when a foal would be threatened.

La Troienne (1926–1954) was one of the most famous and influential Thoroughbred broodmares in twentieth century America. She produced 10 winners including two Hall of Fame inductees while at stud, while her daughters in turn produced many notable offspring. In 2000, pedigree expert Janeen Oliver designated her as the taproot of family 1-x, a designation that was implemented by the Pedigree Online Thoroughbred Database in 2003. Recent matrilineal descendants include 2003 Horse of the Year Mineshaft and Kentucky Derby winners Smarty Jones (2004) and Super Saver (2010).


A ridgling, or rig, is a cryptorchid; a male animal with one or both testicles undescended, usually describing a ram, bull, or male horse, but cryptorchidism also can be an issue in dogs and cats. Because the heat inside the body is too high for sperm to survive, an undescended testicle is non-functional. The condition is most often discussed in the horse world, as the health behavioral issues surrounding adult males with the condition are of concern to owners and handlers of such animals.

Mountain and moorland pony breeds

Mountain and moorland ponies form a group of several breeds of ponies and small horses native to the British Isles. Many of these breeds are derived from semiferal ponies kept on moorland or heathland, and some of them still live in this way, as well as being kept as fully domesticated horses for riding, driving, and other draught work, or for horse showing.

An Austrian Warmblood is a warmblood type of horse registered with the Arbeitsgemeinschaft für Warmblutzucht in Österreich. Although the studbook is made up of jumping and dressage horses from many other countries, the mare base consists of native horses with a long history. The AWÖ keeps an open studbook, in which mares and stallions must pass rigorous inspections before becoming breeding stock.

Studbook selection is a process used in certain breeds of horses to select breeding stock. It allows a breed registry to direct the evolution of the breed towards the ideal by eliminating unhealthy or undesirable animals from the population. The removal of individuals from a population is called culling, and does not suggest killing the animal in question. Typically, culls are castrated or they and their offspring are unable to be registered.

Glossary of equestrian terms List of definitions of terms and concepts related to horses

This is a basic glossary of equestrian terms that includes both technical terminology and jargon developed over the centuries for horses and other equidae, as well as various horse-related concepts. Where noted, some terms are used only in American English (US), only in British English (UK), or are regional to a particular part of the world, such as Australia (AU).


  1. "Oxford Dictionaries | The World's Most Trustegd Dictionary Provider". Oxford Dictionaries. Archived from the original on 2007-09-29. Retrieved 2017-11-12.
  2. Ensminger, M. E. Horses and Horsemanship: Animal Agriculture Series. Sixth Edition. Interstate Publishers, 1990. ISBN   0-8134-2883-1 p. 156
  3. Ensminger, M. E. Horses and Horsemanship: Animal Agriculture Series. Sixth Edition. Interstate Publishers, 1990. ISBN   0-8134-2883-1 p. 150
  4. Ensminger, M. E. Horses and Horsemanship: Animal Agriculture Series. Sixth Edition. Interstate Publishers, 1990. ISBN   0-8134-2883-1 p. 149-150
  5. Houpt, Katherine Albro (2002). "Formation and dissolution of the mare–foal bond". Applied Animal Behaviour Science. 78 (2–4): 319–328. doi:10.1016/S0168-1591(02)00111-9.
  6. "Archived copy". Archived from the original on 2009-09-05. Retrieved 2009-09-30.CS1 maint: archived copy as title (link) Multiple definitions of Mare and its etymological origins. Web site accessed September 30, 2009
  7. 1 2 3 4 5 6 Etymology OnLine Archived 2007-12-14 at the Wayback Machine , accessed November 25, 2007
  8. Vries, Jan de (April 28, 1977). "Altnordisches etymologisches Wörterbuch". E.J. Brill via Google Books.
  9. Brewer, Warren A. (1984). "The resistance of Latin equa 'mare' to replacement". Zeitschrift für vergleichende Sprachforschung. 97 (2): 236–243. JSTOR   40848753.