A gelding is a castrated animal â in English, the term specifically refers to a castrated male horse or other equine. The word comes from the Old Norse geldr (barren). Castration, and 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. A male horse is often gelded to make him more well-behaved and easier to control. Gelding also removes lower quality animals from the gene pool. Horse breeders choose to leave only their best animals as stallions; lesser specimens are gelded, to improve the overall quality of the breed.