When Should I Geld My Colt?

Dr. Lisa Nesson

Written by: Dr. Lisa Nesson

Congratulations on your new colt! If you’re planning on raising your colt to be a breeding stallion, head over to our posts about freezing your stallion’s semen and our pages about Dr. Pat Griffin and his reproductive specialty work to start thinking about that process. If you’re planning on raising a gelding, read on!

What is castration?

Castration is a surgical procedure to remove the testicles and associated structures. Castration is also called cutting, gelding, or emasculating. The surgery is typically done on the farm, under general anesthesia, or under standing sedation. Most veterinarians do the surgery with the colt on the ground, under full sedation, but some veterinarians prefer to do them with the colt standing. The testicles need to be descended into the scrotum. This should happen at birth, but some colts take a little longer. If they have not descended by two years of age, they are considered a cryptorchid, and will need a more complex surgery.

In this video, we go over the best time to geld your colt, from a medical standpoint.

Why should I castrate my colt?

Castration of male horses has long been used as a method of controlling aggressive behavior. The presence of testicles and production of testosterone has a significant impact on the development of a young colts’ attitude and behavior pattern. Stallions often display aggressive or undesirable behavior such as mounting, fighting, or trumpeting. If you want to ensure a well behaved and focused gelding in the future, consider castrating your colt before one year of age.

Gelding your colt also makes management of your horse easier – if you have a stallion, you’ll need to keep him pastured away from mares to prevent unwanted breedings. If you’re not planning on using your horse for reproductive purposes, you should geld him at a young age.

There is some indication that keeping your horse a stallion for a longer period of time will affect their appearance. The longer they stay as stallions, the more likely they are to develop cresty necks. Similarly, the older stallion may not become as tall as a gelding. There is some research to show that testosterone causes growth plates in their legs to close at a younger age, making them a little shorter.

When should I castrate my colt?

We do recognize that there’s some nostalgia and historical perspective on when it’s best to geld your colt. Each breed group, discipline, and industry has a different opinion on when it’s best to geld your colt, and they all recommend different things. We have gelded horses of all ages, including stallions well into their teens. That said, medically speaking, there is no reason to delay castration in most situations. Choosing the best time to geld your colt is a fine line between a horse that is too young and too developed. The most common time to geld a colt is between six and twelve months of age. Here are some reasons why:

Dr. Howard Ketover is helping a new gelding recover from general anesthesia.

Dr. Howard Ketover is helping a new gelding recover from general anesthesia.

  • At three months of age, your colt has adequate testicular development, making the testicles a good size to be able to find them and castrate easily. If you attempt to castrate your colt at too young of an age, the testicles are not very developed, and it’s more difficult to identify and sever them.

  • Recent research has shown that delaying castration past one year of age does create a horse that will have longer term stallion-like behavior. If your horse remains a stallion through even one breeding season (Spring time), even if he’s not actually breeding, this will have a long term impact on his behavior. He will display more stud-like behaviors even after being gelded.

  • As your colt ages, there is more testicular tissue development, as well as increased blood supply to the testicular region. The chances of increased bleeding and other secondary complications are smaller when your geld at a younger age.

  • Most castrations are completed with your horse under general anesthesia. When it comes to recovering your horse from the anesthesia, there is less risk with younger horses. Older horses carry more risk of injuring themselves or their handlers when standing and recovering from anesthesia.

  • Finally, as with people, the younger the patient, the faster the healing times. Younger colts have less testicular tissue and a smaller scrotum, which requires less time to heal.

  • Thinking about gelding your colt? Give us a call to talk through the procedure and set up an appointment. Let’s get it done before his first “breeding” season hits!