Riverina Equine Vet



Colt Castration Aftercare

Timing and Preparation

Castration is surgical removal of the testicles. It is performed on colts to modify behaviour, prevent stallion-like body development, and avoid unwanted pregnancies. Castration is usually performed before the age of 24 months. Any colt older than 9 months of age should not be paddocked with fillies and mares as they may mount and potentially impregnate them. In our area, we like to castrate colts during the cooler months when there is less dust and fewer flies.

It is a good idea to try to visualise or feel for the presence of two testicles before your vet comes to perform a routine castration. In normal colts, the testicles will have descended into the scrotum by the time of birth. Occasionally one testicle does not completely descend into the scrotum but remains in the inguinal canal. In some cases, with time, this high testicle may descend into the scrotum and be more accessible for removal. Colts that retain a testicle in the abdomen are known as “cryptorchid”, meaning hidden testicle. Removal of an undescended testicle, called a “cryptorchid castration”, is more complicated and should be performed in a surgical centre by a veterinarian experience with performing this procedure.

Before castration, the colt should be accustomed to handling and be halter trained, so it can be easily managed during and after surgery. Tetanus immunization is necessary before or at the time of surgery. Postoperative care and monitoring is usually needed for around 2 weeks after castration, so schedule the surgery for a time when you are available to monitor the horse after the procedure. Ideally, you should be comfortable handling the young stallion before having him castrated. In some cases, it can take weeks to months for stallion-like behaviour to decrease after castration. Monitoring at home and caring for the colt according to instructions is essential for a smooth, uncomplicated recovery. The period after castration is also a good time to begin daily training of your young gelding.


The Procedure

At REVS we perform our colt castrations in the field under a short-acting general anaesthesia, with the colt positioned on his back. We have the ability to perform either the traditional emasculator technique or the more recently developed Henderson drill technique. Recent studies have indicated that there is no significant difference in complication rate between these two techniques, however if you have a preference for technique please let us know at the time of booking.

The colt is firstly examined for the presence of two testicles and his overall health is assessed. A sedative is administered, followed by a general anaesthetic 5 minutes later which will render the colt unconscious. An antibiotic injection, an anti-inflammatory injection, and the appropriate tetanus injections are also administered. Once the colt has been positioned on his back, the scrotum is surgically prepared and the surgery completed in a sterile fashion with the incisions left open. The surgical procedure usually takes no longer than 10 minutes, with the general anaesthetic usually lasting 20-30 minutes.

We monitor the horse as he recovers from the anaesthetic which may take 10-15 minutes. Generally speaking, the longer he lies there and ‘sleeps off’ his anaesthetic, the better he will rise. He will be unsteady on his feet for another 5-20 minutes.



The gelding should be monitored closely in the 6 hours immediately after surgery and kept quiet and reasonably confined for the first 12 hours. After this time he should be allowed out into his normal paddock to encourage movement and exercise, which is important to help reduce swelling and facilitate drainage. Occasionally, forced exercise will be required if the gelding is not active enough in the paddock. This can be in the form of 15 minutes trotting at the lunge or in a roundyard, twice daily.

Look for streaming of blood from the wound. Some dripping is to be expected for the first few hours after castration, but call us immediately if blood streams from the wound. Also call us if you observe colic signs or any dramatic increase in scrotal swelling or pink/red tissue protruding from the wound.

You can apply fly spray around the flanks and hindquarters if you wish. Spray from the side. Do not spray directly up into the wounds as fly spray can be very irritating to open wounds.

During days 2 through 5, the scrotum may swell up to 3 times its original size. This is normal. This postoperative swelling is reduced with exercise. The scrotum is usually back to normal size after 5 days but a bit of swelling may persist at the lowest part of the sheath.

Clear, red tinged fluid draining from the wound is normal for the first few days. If the drainage becomes yellow or pus coloured, you should get in touch with us.


Potential Complications

Castration is a routine surgical procedure, but complications can happen. The most common complications include:

  • Bleeding: slow dripping from the surgical incision is normal after the castration. If the drops of blood are too fast to count please call us immediately.
  • Swelling: swelling in the first 24-48 hours post surgery is normal and will vary from horse to horse. Swelling will often appear in the horse’s sheath near the penis (as this is the lowest point and fluid tends to follow gravity). It should begin to reduce after 3-4 days. If swelling suddenly reappears after this time, please call us.
  • Infection: after the testicles are removed, the incisions are not sutured and are allowed to heal as a small open wound. If the incision becomes blocked or closes prematurely, infection can be sealed inside. Post-castration infection usually causes sudden excessive swelling of the scrotal area and sheath and a depressed attitude and appetite. Horses with infections will often have a fever over 38.5°C. This complication is most often seen 2-7 days after castration but can occur anytime.
  • Inguinal hernia: should you notice and pink or red material hanging from the surgical site, please call us immediately. In some horses, the opening in the abdominal wall (inguinal canal) through which the testicles descend into the scrotum is larger or more flexible. In these horses, there is potential for intestines and other abdominal tissue to pass through the inguinal opening and come out the incision (called herniation). Although inguinal hernias are uncommon, they are a life threatening complication and must be dealt with immediately and properly.
  • Pregnancy: a recently castrated gelding can still get a mare in foal for some time after castration because of residual sperm in the urogenital tract. Recently castrated geldings should be kept away from females for at least 30 days.