Castration is a surgical procedure performed by a veterinarian that is defined as the removal of the testicles of a male horse. The procedure can be accomplished through sedation and local anesthesia in a standing position or through general anesthesia and the horse lying on its side (lateral recumbency). This procedure is typically performed once the horse is skeletally mature to reap the beneficial effects of testosterone. 

Why Castration May Be Necessary 

This procedure is typically performed on colts to make them more manageable and easier to train. Castration is also necessary if the horse has minimal breeding value. In horses with potential breeding value, castration may be delayed to determine if the horse has enough performance ability to make him attractive as a future sire.

A growing concern for the unwanted horse has also increased the need for castration. The goal, as a horse owner, is to act responsibly. The plight of the unwanted horse is a growing welfare issue. The Unwanted Horse Coalition, a broad alliance of national equine organizations joined together under the American Horse Council, is working to educate industry groups and help people learn to “own responsibly.” Colts that possess undesirable traits should be gelded so as to not pass these traits on to their offspring.

Undesirable Traits 

In some breed organizations, various traits are often undesirable, but horses that possess these traits are not prevented from participating in events. 

Behavioral Problems 

Stallions are constantly exposed to testosterone and can be aggressive and potentially dangerous to other horses and people. A mature, intact male horse may become progressively more aggressive and difficult to train as he becomes older. Some reports indicate that if horses are left intact too long, as many as 65 percent may continue to express the undesirable traits as learned behavior.

Cryptorchidism 

In some horses, the timing of castration is accelerated due to a condition referred to as cryptorchidism. Cryptorchidism is the retention of one (unilateral) or both (bilateral) testicles. A horse that is cryptorchid is also referred to in layman’s terms as a “ridgling,” a “rig” or a “high flanker.” Non-descended testicles have reduced fertility or are completely sterile as their retention in the inguinal canal makes them ineffective at producing sperm because of the higher temperature. However, retained testicles produce the same amount of testosterone, so stallion-like behavior will remain the same. This trait has long been considered heritable and may be genetically transferred to offspring. 

The Procedure 

In preparation for gelding, the horse should be in good health and current on deworming and immunizations, particularly tetanus. If the horse has never received vaccinations, owners are advised to vaccinate the horse using vaccines recommended by the attending veterinarian and wait two weeks after vaccination to perform the castration procedure. 

When anesthetics were unpredictable, with a narrow safety margin, most horses were castrated standing. However, with today’s safe and effective short-term anesthetics, most horses are gelded and anesthetized while lying on the ground. A new technique for retrieving cryptorchid testicles is through a minimally invasive approach using laparoscopy. During this procedure, a laparoscope (a fiber-optic camera) enters through a small incision in a standing horse’s flank. Another hole is pierced for the instruments. The veterinarian can see what the camera sees through a monitor. The horse will have a much smaller incision on the flank to heal instead of a wound in the belly. The procedure is very atraumatic to the horse since he is standing throughout the entire procedure. 

Post-Surgery 

Following castration, horses should receive a tetanus toxoid booster (if vaccinations are current) or both tetanus toxoid and a tetanus antitoxin injection if the horse has never been vaccinated. Your veterinarian may administer antibiotics/NSAIDS (anti-inflammatories) to your horse after surgery. Your veterinarian will advise you on what he/she feels is best for your horse. If flies are still in season, it is a good idea to apply an insect repellant immediately after the castration surgery. 

Shelter 

It is recommended that the horse be placed in a small paddock or stall for 12 to 24 hours for observation to ensure adequate clotting. If the horse is to be stalled, bed the enclosure with fresh shavings or straw.

Exercise 

Beginning the day after surgery, the horse should be exercised at a trot or on an automatic walker for at least 15 to 20 minutes twice a day to avoid swelling and stimulate drainage of any post-surgical fluid that may have accumulated in the swollen scrotum. Exercise should continue for about two weeks or until healing is complete.

Complications 

Post-surgical complications can occur but are rare. The most common is excessive swelling of the scrotum that can extend down into the lower hind legs. If increased exercise does not resolve the problem, contact your veterinarian. In rare instances, the horse has an unusually large inguinal ring in which intestines may protrude from the incision. This usually occurs within a few hours of the surgical procedure but can happen days later. If this occurs, consider it a true emergency, and contact your veterinarian immediately. 

Behavior 

Depending upon the horse’s age and maturity level, it may take several weeks for the testosterone levels to decrease. Aggression, especially to other horses, may still be seen for this short period. However, stallions castrated after maturity (six years old or older), especially those that have bred mares, may continue to possess stallion-like behavior, which could include the development of an erection and an attempt to mount and breed mares in estrus. 

Semen remains in the horse’s accessory sex glands and the portion of the vas deferens is not removed during surgery. There is usually enough present for one ejaculation. Therefore, gelded mature horses should be quarantined from mares for 14 to 30 days post-surgery. 

Positive Perspective of Castration 

Horse owners can promote equine welfare by becoming educated on castration practices and working proactively to address widespread concerns about the unwanted horse. 

Suppose the goal is to continue to improve a breed and minimize the number of horses that fail to meet expectations. In that case, the surgical procedure of castration should be utilized to decrease the number of unwanted horses. Horse owners can act responsibly by putting the horse first.