Equine Castration Considerations
Castration is surgical removal of the testicles to prevent stallionlike behavior and development, as well as pregnancy in herd settings. Stallions can be gelded as young as nursing foals up until their 20s, though veterinarians typically castrate colts before 2 years of age. Many vets prefer to perform castrations during the cooler months when there are fewer flies.

Colts should be halter-trained and accustomed to handling so they can be eas- ily managed during and after surgery. The veterinarian will often administer a teta- nus immunization before or at the time of surgery. Usually, castration patients need at least two weeks of postoperative care, so schedule the surgery for a time when you can monitor the horse closely.

The procedure

In our practice we usually perform recumbent (down) castration under short-acting general anesthesia. The colt lies on his left side with his right hind leg tied up so we can access the scrotum. We perform the procedure in the field or at the clinic, and usually outside. Some vets prefer to do the procedure with the horse standing and sedated.

Once the horse is sedated and the scrotum surgically prepared, the castration procedure itself only takes about five to 10 minutes. I make a large incision to expose each testicle, then use sterile emasculators to crush the large vessels of the spermatic cord to prevent hemorrhage. It takes about 15 minutes for the colt to recover from the anesthetic. At that point he usually gets up easily with little assistance. He will be unsteady for another five to 20 minutes, after which he can be trailered or moved to a stall.

Potential complications

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


Excessive postoperative bleeding is more common in horses that have clotting abnormalities or very large testicular blood vessels. It can also occur if the vessels are not crushed properly. Most correctly castrated horses bleed very little.

Inguinal hernia

In some horses the opening in the abdominal wall (inguinal canal) through which the testicles descend into the scrotum is large or flexible. In these horses the intestines and other abdominal tissue can pass through the inguinal opening and out the incision (herniation). Although inguinal hernias are uncommon, they are life-threatening complications that must be dealt with immediately.


Castration incisions are not sutured but, rather, allowed to heal from the inside out. If theincision closes prematurely, infection can get sealed inside. Post-castration infection usually causes excessive swelling of the scrotal area and sheath and a depressed attitude and appetite. Horses with infections often have a fever over 102.5 degrees Fahrenheit. Signs usually appear two to five days after castration, but infection can occur anytime.


For 24 hours after castration, keep your gelding confined and calm in an up to 20-by-20 stall or corral. During the first six hours after surgery, look in on him every few hours, as directed.

Some slow-dripping blood is normal in the hours after castration, but call your vet immediately if blood streams from the wound for more than a few minutes.

Exercise is important to help reduce swelling and facilitate drainage. We recommend starting a controlled exercise program (15 minutes of longeing or ponying at the trot, for example, once or twice daily) 24 hours after the procedure. The horse may initially seem stiff, but this usually resolves with more exercise.

In warm weather apply fly spray around the flanks and hindquarters. Spray from the side and not up into the wounds.

The incision will contract over a few days to a much smaller wound and then fill with a bed of red tissue, healing within 12 to 14 days. Any drainage should subside after a few days to a week.

Days 2-5 the scrotum might swell up to three times its original size. This is normal and often goes down with exercise. The scrotum is usually back to normal size after five 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-colored, call your veterinarian. Also call your vet immediately if:

  • You have questions concerning the castration or its healing.
  • Your
  • You observe excessive swelling the scrotum sheath.
  • Your horse’s temperature in the morning, before exercise, is higher than 102.
  • You see excessive bleeding or drainage from> the scrotal incision.
  • You observe tissue hanging out of the incision.

In some cases, it can take weeks to months for stallionlike behavior to decrease after castration. Monitoring at home and caring for the colt according to veterinarian instructions is essential for a smooth, uncomplicated recovery.