Becoming educated on the entire process of castrating horses can only help you make decisions that are best for your horse. Castration has been used to control masculine/aggressive behavior in the male horse for hundreds of years. In medieval times, kings rode stallions, and people of less stature often were described as riding geldings. Castration also is called gelding, cutting, or emasculating. The scientific name for castration is orchidectomy–orchid meaning testicle and -ectomy meaning to remove or resect. Orchidectomy therefore is the surgical removal of a testicle.

Castrating horses in the past was, of course, not always performed by licensed veterinarians. Even today in some cultures it is performed by a lay person. Although it is one of the most common surgeries performed by a veterinarian, it should never be considered routine, as the procedure can have very serious complications. Furthermore, the follow-up care is extremely important. In this article, we’ll see how an orchidectomy is performed in the horse, when it can be performed, potential complications, and the myths behind castration in horses.

Why Castration?

Castration in any species involves the removal of one or both testicles and associated structures (such as the epididymis) and part of the spermatic cord. The spermatic cord is the tube-like structure that contains the blood supply (veins and artery), ductus deferens, and nerve supply to the testicle. Castration usually is performed in male horses of inferior breeding stock, in cases of cryptorchidism, or in stallions which are difficult to manage. Some owners believe that stallions perform better than geldings; this is common in several disciplines.

The testicles are the organs responsible for producing testosterone (the main hormone that creates stallion-like physical features and behavior). Removal of both testicles usually rids the horse of unwanted stallion-like behavior, including screaming at and fighting with other horses, attempting to mount other horses, erection, masturbation, and potentially aggressive behavior toward humans. However, when castration is performed at a late age and/or after the horse has been used to breed mares, is not always successful in abolishing learned stallion-like behavior. Even though the horse will not be able to reproduce, the behavior of mounting mares in the pasture in an attempt to breed and aggressive behavior with other horses might not