Gelding a colt or a stallion is the most common routine surgery performed on a horse. It is a simple procedure, but a surgery that can have its share of complications despite the frequency with which it is done.

The most common method of castration is the surgical removal of both testicles using a tool called an emasculator. These come in a variety of forms but are basically an instrument that clamps and crushes the cord including the blood vessels, above the testicle, before the testicle is removed. In many cases the emasculators have a cutting edge that cuts the testicle off at the same time it crushes the cord. Some practitioners prefer not to use the cutting edge on the emasculators and manually sever the testicle after the cord has been crushed.

Another tool used for gelding is the Henderson equine castration instrument, which clamps on the cord above the testicle and, like a drill, causes the cord to twist round and round until the cord breaks, effectively sealing the blood vessels as it goes. Some veterinarians prefer to ligate or tie off the testicular vessels prior to cutting the testicle off, as they believe this reduces the risk of excessive bleeding. Other vets are happy to just emasculate the cord including the blood vessels and not use suture material in the site.

My routine castrations are all done using a pair of emasculators and the cord is not tied off unless there are unusual circumstances that have dictated otherwise. Several years ago, there was a product available that was used “off-label” to chemically castrate colts and stallions. The product was a vaccine used to inhibit the breeding hormone GnRH and was marketed as a method to stop mares cycling. When this injection was given, the testicles reduced in size and the horses behaved like geldings, however, the results were inconsistent in their duration and a return to fertility was not guaranteed.

Castration can be performed either using a general anaesthesia or as a standing procedure whereby the colt is heavily sedated, and the testicles are removed using a local anaesthesia. I am happy to perform the task either way, but to do a standing castration properly, the horse must be well handled or extremely quiet. If I cannot walk up to an un-sedated colt and palpate his testicles without him kicking or trying to lie down, I will not do the castration as a standing procedure and opt for a general anaesthesia.

FOR AND AGAINST

There are for and against arguments as to whether a standing castration is better or worse than using a GA to geld a colt. The advantage of a standing castration over a castration using general anaesthesia is related to the risks associated with anaesthesia such as the space required to safely anaesthetise a horse, the weather (wet and muddy environments), the small but real risk of an adverse drug reaction causing death, and the risks associated with the horse going down when induced and/or getting up after as the anaesthesia wears off. The drugs available for field anaesthesia are far better nowadays than decades ago, so horses are more stable when waking up from anaesthesia. In previous decades, horses would be very ataxic and have great difficulties in rising, sometimes breaking a limb when they tried to rise to their feet.

The major advantages of a GA over a standing castration are that it is safer for the handler and the vet and there is more access to the scrotum and testicles, which is particularly important in at-risk colts and when complications occur during the castration.

A “rig” is the term used to describe a colt that has one testicle in the scrotum and one testicle still retained in the abdomen. The retained testicle can be anywhere from just inside the inguinal ring to the region of the kidneys. Castration of these colts will require a GA as the veterinarian requires access into the abdomen to remove the retained testicle. It is possible to have a colt with two retained testicles and this is referred to as a bilateral cryptorchid.

In most cases, castration is an elective surgery and can be performed at any time from shortly after birth until the stallion is in his later years, although it is more common to be performed from 6 months to 4 years of age. There are instances when the surgery is performed as part of an emergency procedure such as large inguinal hernias (usually in foals), trauma to the testicle, torsion of the testicle or with a testicular tumour.

Stallions gelded later in life will commonly retain many of their masculine tendencies even though they no longer have testicles. It takes about 6 weeks for a colt or stallion to lose the effects of testosterone, so it is important not to run a colt or stallion with a mare until this time has passed.

COMPLICATIONS

There are several complications that can occur during the castration process, but most complications occur in the hours to days or early weeks after the surgery has been performed.

Haemorrhage or excessive bleeding is not an uncommon problem. Most castrations will bleed to a degree after the procedure is performed, particularly in the cases where ligation of the cord is not performed. In castrations where the cords are ligated before the testicle is resected, there is less blood from the cord but still some blood flow from the skin vessels in the scrotum as the scrotal incision is not usually sutured closed. In some cases, more so those castrations done under sterile conditions in a hospital setting, the scrotal wound is closed and so no blood is expected. For horses where the bleeding is excessive, the two main treatment protocols are to pack the wound with absorbent material to slow down the blood flow and allow the vessels to seal or to go in surgically and locate the bleeding vessel and tie or clamp this off.

Infection is another of the more frequently encountered complications. This can involve the superficial soft tissue areas within the scrotum and are relatively easy to treat, or less frequently, extend deep into the cord remnant and form what is known as a scirrhous cord. A scirrhous cord usually presents as an enlarged, painful scrotum that may or may not be discharging pus but causes a lot of discomfort to the gelding. It will sometimes result in a visible lameness due to physical size and degree of pain in the inguinal area. Treatment usually requires surgical resection of the infected cord as only treating with antibiotics seldom is enough to resolve the infection. On a rare occasion it is possible for the infection to travel up into the abdomen from the castration site and cause a peritonitis or infection in the abdomen. Peritonitis can be life-threatening and requires more intensive treatment.

A seroma is the accumulation of fluid (serum) within the scrotum seen rarely after the scrotal wound is healed. It gives the impression of a testicle within the scrotum and often owners are concerned the vet has left a testicle behind (or that the horse had three testicles because they saw two testicles removed!). If the seroma is sterile, meaning there is no infection in the fluid, it will remain as a small ball of fluid and require no treatment. If the seroma is large and either causes the horse discomfort or worries the owner, it can be drained surgically.

Evisceration of the abdominal contents through the surgical opening in the scrotum is a rare event, but if it occurs, it can be fatal. The testicles are enclosed within a tunic of tissue that is a continuation of the lining of the abdomen. When the tunic is opened to remove the testicle, it indirectly leaves an opening that communicates with the abdominal cavity and can allow the intestines to prolapse through the wound and become exposed to the environment. This is a medical emergency and needs to be seen by a veterinarian immediately.

“There are several complications
that can occur.”

The weight of the intestines continues to pull more of the intestinal contents through the wound and if not addressed immediately, can result in the intestines reaching the ground, being traumatised, or being trampled on by the horse himself. It is vital if the owner sees any intestine protruding through the wound that they call the vet immediately and take all reasonable care to prevent further prolapse of the intestines until the vet arrives. This means restricting the horse from walking or running around, and if possible, getting a large clean wet sheet and using it as a temporary sling to support the intestines that are exposed and prevent them from touching the ground.

If a vet is not available and a sheet can be used to protect and support the intestines, I would recommend the horse be floated immediately to a veterinary hospital. Treatment is centred around decontaminating the exposed intestines, replacing the intestines back into the abdomen and preventing further prolapse occurring. Certain horse breeds are more prone to evisceration, and these include Standardbreds, draught breeds and Tennessee Walking Horses.

Colts that have had a history of an inguinal hernia as a foal or have a family history of inguinal hernias or post castration eviscerations are at high risk of developing this complication, so it is vital to inform the vet of any history of these issues prior to the procedure so preventative measures can be used. At-risk horses should have their cord and cremaster cord ligated at surgery and in some cases, the inguinal ring surgically closed, or the wound packed to minimise the risk of intestines protruding down and through into the scrotum.

Omentum is a fold of peritoneum that contains fatty cells and looks very lacey. It connects several abdominal structures in the abdomen and can also protrude down through the incision like the intestines. Whilst this causes owners a lot of distress when it happens, it is far better to see omentum than loops of intestine protruding down, as the omentum tends to plug the inguinal ring and prevent the intestines from eviscerating. Treatment for omentum prolapse is less intensive than for intestines that protrude out as unlike the intestines, the omentum can be ligated and removed and does not need to be returned into the abdomen.

Tetanus has occurred in unvaccinated horses and vaccinating your horses prior to them being castrated will eliminate this unnecessary risk. If unvaccinated, the colt should be given tetanus prophylaxis at the time of the surgery. EQ

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