Stallion

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.

Temperament varies widely based on genetics and training, but because of their instincts as herd animals, they may be prone to aggressive behavior, particularly toward other stallions, and thus require careful management by knowledgeable handlers.

Young male horses without mares of their own usually form small, all-male, "bachelor bands" in the wild.

Erection and protrusion take place gradually, by the increasing tumescence of the erectile vascular tissue in the corpus cavernosum penis.

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.

[10] 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.

Some stallions become very anxious or temperamental in a herd setting and may lose considerable weight, sometimes to the point of a health risk.

[17] Complete isolation has significant drawbacks; stallions may develop additional behavior problems with aggression due to frustration and pent-up energy.

Examples include the Lipizzan stallions of the Spanish Riding School in Vienna, Austria, where the entire group of stallions live part-time in a bachelor herd as young colts, then are stabled, train, perform, and travel worldwide as adults with few if any management problems.

Though compromises may need to be made in expectations for both athletic performance and 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.

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.

[23] 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.

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.