# Stallion

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Male horse that has not been castrated

For other uses, see [Stallion (disambiguation)](/source/Stallion_(disambiguation)).

A stallion

A stallion's secondary characteristics include heavier muscling than is seen in mares or geldings, often with muscular development along the crest of the neck.

A **stallion** is an adult male [horse](/source/Horse) that has not been gelded ([castrated](/source/Neutering)). Stallions follow the [conformation](/source/Horse_conformation) and [phenotype](/source/Phenotype) of their [breed](/source/Horse_breed), but within that standard, the presence of [hormones](/source/Hormone) such as [testosterone](/source/Testosterone) may give stallions a thicker, "cresty" neck, as well as a somewhat more muscular physique as compared to female horses, known as *[mares](/source/Mare)*, and castrated males, called *[geldings](/source/Gelding)*.

Temperament varies widely based on [genetics](/source/Genetics) and [training](/source/Horse_training), but because of their [instincts](/source/Instincts) as herd animals, they may be prone to aggressive behavior, particularly toward other stallions, and thus require careful management by knowledgeable handlers. With proper training and management, stallions are effective equine athletes at the highest levels of many disciplines, including [horse racing](/source/Horse_racing), [horse shows](/source/Horse_show), and international [Olympic](/source/Equestrian_at_the_Summer_Olympics) competition.

"Stallion" is also used to refer to males of other equids, including [zebras](/source/Zebras) and [donkeys](/source/Donkeys).

## Herd behavior

Main article: [Horse behavior](/source/Horse_behavior)

Stallion exhibiting the [flehmen response](/source/Flehmen_response)

Young female horses usually leave their band and join one with a different stallion from the one that sired them. Young male horses without mares of their own usually form small, all-male, "bachelor bands" in the wild. Living in a group gives these stallions the social and protective benefits of living in a herd. A [bachelor herd](/source/Bachelor_herd) may also contain older stallions who have lost their herd in a challenge.[1]

## Reproductive anatomy

See also: [Horse breeding](/source/Horse_breeding), [Horse anatomy](/source/Horse_anatomy#Stallion), and [Horse sheath cleaning](/source/Horse_sheath_cleaning)

[Genitourinary system](/source/Genitourinary_system) of a stallion

The external genitalia comprise the testes and the penis.

The [testes](/source/Testes) are suspended horizontally within the [scrotum](/source/Scrotum). The testes of an average stallion are ovoid, 8 to 12 cm (3.1 to 4.7 in) long, 6 to 7 cm (2.4 to 2.8 in) high, and 5 cm (2.0 in) wide.[2]

Stallions have a musculocavernosus [penis](/source/Penis)[3] with a well-developed [glans](/source/Glans_penis).[4] When non-erect, it is quite flaccid and contained within the sheath. The [retractor penis muscle](/source/Retractor_muscle_of_the_penis) is relatively underdeveloped. Erection and protrusion take place gradually, by the increasing [tumescence](/source/Tumescence) of the erectile vascular tissue in the *[corpus cavernosum penis](/source/Corpus_cavernosum_penis)*.[5] When not erect, the penis is housed within the prepuce or [penile sheath](/source/Penile_sheath),[6][7] 50 cm (20 in) long and 2.5 to 6 cm (0.98 to 2.36 in) in diameter with the distal end 15 to 20 cm (5.9 to 7.9 in) free in the prepuce. The [retractor muscle](/source/Retractor_penis_muscle) contracts to retract the penis into the sheath and relaxes to allow the penis to extend from the sheath. When [erect](/source/Erection), the penis increases in length and thickness by 50% while the thickness of the glans increases by four to five times. The [urethra](/source/Urethra) opens within the **urethral fossa**, a small pouch at the distal end of the glans.[8] A structure called the urethral process projects beyond the glans.[9]

The internal genitalia comprise the [accessory sex glands](/source/Accessory_sex_glands), which include the [vesicular glands](/source/Vesicular_glands), the [prostate gland](/source/Prostate_gland) and the [bulbourethral glands](/source/Bulbourethral_glands).[10] These contribute fluid to the [semen](/source/Semen) at [ejaculation](/source/Ejaculation), but are not strictly necessary for fertility.[2][11]

## Management and handling of domesticated stallions

See also: [Horse breeding](/source/Horse_breeding), [Horse training](/source/Horse_training), and [Horse care](/source/Horse_care)

Even well-trained stallions require firm and consistent handling by experienced individuals.

Stallions are trained and managed in a variety of ways, depending on the region of the world, the owner's philosophy, and the individual stallion's temperament. In all cases, however, stallions have an inborn tendency to attempt to dominate both other horses and human handlers, and will be affected to some degree by proximity to other horses, especially [mares](/source/Mare_(horse)) in [heat](/source/Mare#Reproductive_cycle). They must be trained to behave with respect toward humans at all times or else their natural aggressiveness, particularly a tendency to bite, may pose a danger of serious injury.[1]

The advantage of natural types of management is that the stallion is allowed to behave "like a horse" and may exhibit fewer [stable vices](/source/Stable_vices). In a harem model, the mares may "cycle" or achieve estrus more readily. Proponents of natural management also assert that mares are more likely to become pregnant in a natural herd setting. Some stallion managers keep a stallion with a mare herd year-round, others will only turn a stallion out with mares during the breeding season.[12]

In some places, young domesticated stallions are allowed to live separately in a "bachelor herd" while growing up, kept out of sight, sound or smell of mares. A Swiss study demonstrated that even mature breeding stallions kept well away from other horses could live peacefully together in a herd setting if proper precautions were taken while the initial herd hierarchy was established.[13]

As an example, in the [New Forest](/source/New_Forest), England, breeding stallions run out on the open Forest for about two to three months each year with the mares and youngstock. On being taken off the Forest, many of them stay together in bachelor herds for most of the rest of the year.[14][15][16] New Forest stallions, when not in their breeding work, take part on the annual [round-ups](/source/Muster_(livestock)), working alongside mares and geldings, and compete successfully in many disciplines.[17][18]

There are drawbacks to natural management, however. One is that the breeding date, and hence foaling date, of any given mare will be uncertain. Another problem is the risk of injury to the stallion or mare in the process of natural breeding, or the risk of injury while a hierarchy is established within an all-male herd. Some stallions become very anxious or temperamental in a herd setting and may lose considerable weight, sometimes to the point of a health risk. Some may become highly protective of their mares and thus more aggressive and dangerous to handle. There is also a greater risk that the stallion may escape from a pasture or be stolen. Stallions may break down fences between adjoining fields to fight another stallion or mate with the "wrong" herd of mares, thus putting the pedigree of ensuing foals in question.[19]

Aggressive and even violent behavior between stallions not habitually living together or in the presence of mares adds to the challenges in stallion management.

Provided with sufficient space and food with no distractions from mares in estrus, even stallions previously used for breeding may coexist peacefully. Not all individuals are suited for this kind of arrangement, however.

Complete isolation has significant drawbacks; stallions may develop additional behavior problems with aggression due to frustration and pent-up energy. As a general rule, a stallion that has been isolated from the time of weaning or sexual maturity will have a more difficult time adapting to a herd environment than one allowed to live close to other animals. As horses are instinctively social creatures, even stallions are believed to benefit from being allowed social interaction with other horses, though proper management and cautions are needed.[13]

Properly trained stallions can live and work close to mares and to one another. Examples include the [Lipizzan](/source/Lipizzan) stallions of the [Spanish Riding School](/source/Spanish_Riding_School) in Vienna, [Austria](/source/Austria), where the entire group of stallions live part-time in a bachelor herd as young [colts](/source/Colt_(horse)), then are stabled, train, perform, and travel worldwide as adults with few if any management problems. Even stallions who are unfamiliar with each other can work safely in reasonable proximity if properly trained; the vast majority of [Thoroughbred](/source/Thoroughbred) horses on the racetrack are stallions, as are many equine athletes in other forms of competition. Stallions are often shown together in the same ring at [horse shows](/source/Horse_show), particularly in [halter](/source/Halter_(horse_show)) classes where their [conformation](/source/Horse_conformation) is evaluated. In horse show performance competition, stallions and mares often compete in the same arena with one another, particularly in [Western](/source/Western_pleasure) and [English](/source/English_pleasure) "pleasure"-type classes where horses are worked as a group. Overall, stallions can be trained to keep focused on work and may be brilliant performers if properly handled.[20]

A [breeding](/source/Horse_breeding) stallion is more apt to present challenging behavior to a human handler than one who has not bred mares, and stallions may be more difficult to handle in spring and summer, during the breeding season, than during the fall and winter. Some stallions are used for both [riding](/source/Equestrianism) and breeding at the same general time of year. Though compromises may need to be made in expectations for both athletic performance and [fertility](/source/Fertility) rate, well-trained stallions with good temperaments can be taught that breeding behavior is only allowed in a certain area, or with certain cues, equipment, or with a particular handler.[21][22]

## Geldings

Main article: [Gelding](/source/Gelding)

If a stallion is not to be used for breeding, castrating (gelding) the male horse will allow it to live full-time in a herd with both males and females, reduce aggressive or disruptive behavior, and allow the horse to be around other animals without being seriously distracted.[23] If a horse is not to be used for breeding, it can be gelded prior to reaching sexual maturity. A horse gelded young may grow taller[23] and behave better if this is done.[24] Older stallions that are sterile or otherwise no longer used for breeding may also be gelded and will exhibit calmer behavior, even if previously used for breeding. However, they are more likely to continue stallion-like behaviors than horses gelded at a younger age, especially if they have been used as a breeding stallion. Modern surgical techniques allow [castration](/source/Castration) to be performed on a horse of almost any age with relatively few risks.[25]

In most cases, particularly in modern industrialized cultures, a male horse that is not of sufficient quality to be used for breeding will have a happier life without having to deal with the instinctive, hormone-driven behaviors that come with being left intact. Geldings are safer to handle and present fewer management problems.[24]

Some in the [animal rights](/source/Animal_rights) community maintain that castration is mutilation and damaging to the animal's psyche.[26]

### Ridglings

Main article: [Ridgling](/source/Ridgling)

A [ridgling](/source/Ridgling) or "rig" is a [cryptorchid](/source/Cryptorchidism), a stallion which has one or both testicles undescended. If both testicles are not descended, the horse may appear to be a gelding, but will still behave like a stallion. A gelding that displays stallion-like behaviors is sometimes called a "false rig".[27] In many cases, ridglings are [infertile](/source/Infertility), or have fertility levels that are significantly reduced. The condition is most easily corrected by gelding the horse. A more complex and costly surgical procedure can sometimes correct the condition and restore the animal's fertility, though it is only cost-effective for a horse that has very high potential as a breeding stallion. This surgery generally removes the non-descended testicle, leaving the descended testicle, and creating a horse known as a monorchid stallion. Keeping cryptorchids or surgically-created monorchids as breeding stallions is controversial, as the condition is at least partially genetic and some handlers claim that cryptorchids tend to have greater levels of behavioral problems than normal stallions.[28][29]

## See also

- [Horse behavior](/source/Horse_behavior)

- [Horse breeding](/source/Horse_breeding)

## References

1. ^ [***a***](#cite_ref-Gender_1-0) [***b***](#cite_ref-Gender_1-1) Release, Press (June 29, 2007). ["Gender Issues: Training Stallions"](http://www.thehorse.com/viewarticle.aspx?ID=9881). The Horse. Retrieved November 6, 2011.

1. ^ [***a***](#cite_ref-UWMadison_2-0) [***b***](#cite_ref-UWMadison_2-1) ["The Stallion: Breeding Soundness Examination & Reproductive Anatomy"](https://web.archive.org/web/20070716140038/http://www.wisc.edu/ansci_repro/101equinelab/reproduction/stallion_exam.html). University of Wisconsin-Madison. Archived from [the original](http://www.wisc.edu/ansci_repro/101equinelab/reproduction/stallion_exam.html) on July 16, 2007. Retrieved July 7, 2007.

1. **[^](#cite_ref-3)** Budras, Klaus-Dieter; Sack, W. O.; Rock, Sabine (2003). [*Anatomy of the Horse: An Illustrated Text*](https://www.google.com/books/edition/Anatomy_of_the_Horse/CUFN_K0AHgsC?hl=en&gbpv=1&pg=PA78&printsec=frontcover). Schlütersche. [ISBN](/source/ISBN_(identifier)) [978-3-89993-003-0](https://en.wikipedia.org/wiki/Special:BookSources/978-3-89993-003-0).

1. **[^](#cite_ref-4)** NICKEL (November 11, 2013). [*The Viscera of the Domestic Mammals*](https://www.google.com/books/edition/The_Viscera_of_the_Domestic_Mammals/0rDhBwAAQBAJ?hl=en&gbpv=1&pg=PA346&printsec=frontcover). Springer Science & Business Media. [ISBN](/source/ISBN_(identifier)) [978-1-4757-6814-5](https://en.wikipedia.org/wiki/Special:BookSources/978-1-4757-6814-5).

1. **[^](#cite_ref-Sarkar_5-0)** Sarkar, A. (2003). *Sexual Behaviour in Animals*. Discovery Publishing House. [ISBN](/source/ISBN_(identifier)) [978-81-7141-746-9](https://en.wikipedia.org/wiki/Special:BookSources/978-81-7141-746-9).

1. **[^](#cite_ref-6)** Schumacher, James (2006). "Penis and prepuce". [*Equine Surgery 2*](https://web.archive.org/web/20170828144535/http://www.ovs0.com/PDF/20335316.pdf) (PDF). pp. 540–557. Archived from [the original](http://www.ovs0.com/PDF/20335316.pdf) (PDF) on August 28, 2017.

1. **[^](#cite_ref-HayesKnightbridge2002_7-0)** Hayes, Captain M. Horace; Knightbridge, Roy (2002). [*Veterinary Notes for Horse Owners: New Revised Edition of the Standard Work for More Than 100 Years*](https://books.google.com/books?id=rcNw1sUPmdsC&pg=PA364). Simon and Schuster. p. 364. [ISBN](/source/ISBN_(identifier)) [978-0-7432-3419-1](https://en.wikipedia.org/wiki/Special:BookSources/978-0-7432-3419-1).

1. **[^](#cite_ref-McKinnonSquires2011_8-0)** McKinnon Angus O.; Squires, Edward L.; Vaala, Wendy E.; Varner, Dickson D. (2011). [*Equine Reproduction*](https://books.google.com/books?id=QPJQT6-g-YMC&q=penis). John Wiley & Sons. [ISBN](/source/ISBN_(identifier)) [978-0-470-96187-2](https://en.wikipedia.org/wiki/Special:BookSources/978-0-470-96187-2).

1. **[^](#cite_ref-9)** Equine Research (2005). [*Horseman's Veterinary Encyclopedia, Revised and Updated*](https://books.google.com/books?id=RXhcr53lkbwC&q=penis). Lyons Press. [ISBN](/source/ISBN_(identifier)) [978-0-7627-9451-5](https://en.wikipedia.org/wiki/Special:BookSources/978-0-7627-9451-5).

1. **[^](#cite_ref-M.C.G.D.2008_10-0)** Morel, M.C.G.D. (2008). [*Equine Reproductive Physiology, Breeding and Stud Management*](https://books.google.com/books?id=iz1C6pSwq40C&q=accessory+glands). CABI. [ISBN](/source/ISBN_(identifier)) [978-1-78064-073-0](https://en.wikipedia.org/wiki/Special:BookSources/978-1-78064-073-0).

1. **[^](#cite_ref-11)** Parker, Rick (January 13, 2012). [*Equine Science*](https://books.google.com/books?id=cCt9EKwu9r0C&q=penis) (4th ed.). Cengage Learning. p. 240. [ISBN](/source/ISBN_(identifier)) [978-1111138776](https://en.wikipedia.org/wiki/Special:BookSources/978-1111138776).

1. **[^](#cite_ref-12)** Strickland, Charlene (July 5, 2007). ["Return to Nature With Pasture Breeding"](http://www.thehorse.com/ViewArticle.aspx?ID=159&nID=5&n=Stallion). The Horse. Retrieved November 6, 2011.

1. ^ [***a***](#cite_ref-pasture_13-0) [***b***](#cite_ref-pasture_13-1) Lesté-Lasserre, Christa (June 8, 2010). ["Pasturing Stallions Together Can Work, Says Study"](http://www.thehorse.com/ViewArticle.aspx?ID=16476). The Horse. Retrieved November 6, 2011.

1. **[^](#cite_ref-14)** ["MINUTES of the Court of Verderers"](http://www.verderers.org.uk/oct05mins.pdf) (PDF). October 19, 2005. p. 3. Retrieved December 26, 2011.(Document refers to the local group-keeping of stallions: 15 stallions on winter grazing at New Park, 20 stallions at Cadland, and to free winter grazing to all stallions passed to run on the Forest, "all those stallions will now remain at our two secure grazing sites at New Park and the Manor of Cadland")

1. **[^](#cite_ref-15)** ["MINUTES of the Court of Verderers"](http://www.verderers.org.uk/apr09mins.pdf) (PDF). April 15, 2009. p. 3. Retrieved December 24, 2011.(Document refers to the group-keeping of 22 stallions at Cadland)

1. **[^](#cite_ref-16)** ["New Forest Pony Stallions"](http://www.nfstallions.info/). Nfstallions.info. October 2, 2011. Retrieved November 6, 2011.(This site has photographs and video of group-kept stallions)

1. **[^](#cite_ref-17)** ["Ellingham show ringside attractions"](https://web.archive.org/web/20120331123606/http://www.ellinghamshow.co.uk/attractions.html). Ellinghamshow.co.uk. Archived from [the original](http://www.ellinghamshow.co.uk/attractions.html) on March 31, 2012. Retrieved November 6, 2011.

1. **[^](#cite_ref-18)** ["Winning Olympia Quadrille"](https://web.archive.org/web/20120415021613/http://www.newforestpony.com/news_quadrille_dec10.php). The New Forest Pony. December 18, 2010. Archived from [the original](http://www.newforestpony.com/news_quadrille_dec10.php) on April 15, 2012. Retrieved November 6, 2011.

1. **[^](#cite_ref-19)** McDonnell, Sue. ["Keeping Horses in Harems"](http://www.thehorse.com/ViewArticle.aspx?ID=6283). The Horse. Retrieved November 6, 2011.

1. **[^](#cite_ref-20)** Strickland, Charlene. ["Males as Athletes"](http://www.thehorse.com/ViewArticle.aspx?ID=772&nID=5&n=Stallion). The Horse. Retrieved November 6, 2011.

1. **[^](#cite_ref-21)** Mendell, Chad (2005). ["Stallion Handling (AAEP 2005)"](http://www.thehorse.com/ViewArticle.aspx?ID=6549). The Horse. Retrieved November 6, 2011.

1. **[^](#cite_ref-22)** McDonnell, Sue. ["Keeping Stallions Focused"](http://www.thehorse.com/ViewArticle.aspx?ID=8808). The Horse. Retrieved November 6, 2011.

1. ^ [***a***](#cite_ref-Netvet_23-0) [***b***](#cite_ref-Netvet_23-1) ["The Advantages of Spaying and Castrating Horses"](http://www.netvet.co.uk/equine/neutering/advantages-of-neutering-horses.htm). Netvet UK. Retrieved March 3, 2014.

1. ^ [***a***](#cite_ref-Hill_24-0) [***b***](#cite_ref-Hill_24-1) Hill, Cherry (2008). ["Gelding and Aftercare"](http://www.horsekeeping.com/horse_health_care/gelding_and_aftercare.htm). Cherry Hill. Retrieved March 3, 2014.

1. **[^](#cite_ref-25)** Cable, Christina S. (April 1, 2001). ["Castration in the Horse"](http://www.thehorse.com/articles/10024/castration-in-the-horse). The Horse. Retrieved March 3, 2014.

1. **[^](#cite_ref-26)** Schmid, Mark (February 20, 2010). ["What is Castration / Spaying / Neutering?"](http://www.animaldignity.org/generaltopics/sexualityofanimals/soawhatiscastration/main_xx.php). Organization for Animal Dignity. Retrieved November 6, 2011.

1. **[^](#cite_ref-27)** ["When is a gelding actually a rig?"](http://www.horseandhound.co.uk/horsecare/1370/57411.html). *Horse & Hound*. February 11, 2013. Retrieved March 3, 2014.

1. **[^](#cite_ref-28)** Paulick, Ray (November 5, 2004). ["Surgery to Address Roman Ruler's Ridgling Condition"](http://www.thehorse.com/articles/11695/surgery-to-address-roman-rulers-ridgling-condition). The Horse. Retrieved March 3, 2014.

1. **[^](#cite_ref-29)** Smith Thomas, Heater (July 1, 2004). ["Stallion or Gelding?"](http://www.thehorse.com/articles/11443/stallion-or-gelding). The Horse. Retrieved March 3, 2014.

## External links

Wikimedia Commons has media related to [Stallions](https://commons.wikimedia.org/wiki/Category:Stallions).

- [Update on sheath cleaning, with how-to video link](http://www.thehorse.com/articles/31873/spring-cleaning-dont-forget-sheath-cleaning) [Archived](https://web.archive.org/web/20210706103300/https://thehorse.com/115934/male_horse-health-care-dont-forget-sheath-cleaning/) July 6, 2021, at the [Wayback Machine](/source/Wayback_Machine)

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