Disclaimer: The following is only general information. If you believe that your horse has a problem please call your veterinarian as soon as possible.

741_Castration1Gelding, castration or cutting all mean the same thing: they are a surgical procedure that removes the testicles of a male horse. A veterinarian can perform this procedure either by sedating the horse and using a local anaesthetic while the horse is standing, or by administering a general anaesthetic with the horse lying on its side.

There are also two methods of treating the incision. The traditional method leaves the wound open, allowing it to heal on its own, while the other method closes the incision with sutures (stitches). You should discuss these various methods with your equine veterinarian to decide which one is right for your horse. Your horse’s age at the time of castration may be an important factor.

A Stallion’s Reproductive System


Why geld/castrate your horse?

The more appropriate question is ‘Why not?’.

Male horses that are left ‘entire’ or ‘intact’ (colts and stallions) are extremely difficult to manage. Even the quietest stallion can have a dramatic personality change in Spring, when they smell mares on the wind.

764 Stallions

If you want to keep a stallion you will need special facilities (unless he’s a Miniature or Shetland). Fences will need to be higher and stronger and you will need enough room to separate your colt or stallion from your mares, or other people’s mares for that matter.

Again, behaviour issues can range from difficult to extremely dangerous for other horses, you, your family, and other people. Stallions are constantly exposed to testosterone (male hormone), which drives their behaviour. A mature, intact male horse may become progressively more aggressive and difficult to train as he becomes older.

There is also a growing concern with ‘unwanted’ horses across the USA, UK and Australia. This is a growing welfare issue that has all the animal welfare organisations in these countries extremely concerned.

Another consideration for people who wish to breed, and own a registered ‘breed’ colt (such as Arabian, Welsh, AQH, ASH, to name just a few), is that you may want to put off castrating him until you can tell if he is going to develop into a worthwhile breeding prospect. At this time you should be looking for the existence or development of any undesirable traits. There may be obvious conformation problems or specific traits that your breed organisation finds undesirable. This will not prevent you from participating in events but it would mean that your colt may not be a good breeding prospect.

765 lineup thmWe all fall in love with our young horses so get an independent opinion by exhibiting your colt in a competitive breed show (winning your local show against a limited line-up doesn’t count), discuss with the judge, discuss with top breeders, and seek advice from experienced commercial breeders. But remember if you don’t have experience with stallions it may become a very dangerous experience.

When should you castrate?

740_TesticlesYou can castrate as soon as both testes are fully descended into the scrotum, however, unlike small animals, veterinarians tend to castrate colts when they are about 12 months old (yearlings).

Colts should be gelded before they reach sexual maturity if you wish to avoid unwanted foals or unwanted stallion behaviour. Just like humans, sexual maturity can vary from colt to colt, however a two-year-old colt is perfectly capable of ‘covering’ a mare. There have even been reports of foals (between 6 to 12 months) covering mares, so managing your colt before he is gelded is a very important issue – this may involve removing him from mares no later than 6 months of age.

The best time to geld a horse is always a subject for debate, with some feeling that if you geld early they wont grow and others arguing that if you geld early they grow taller.

The best person to ask is your equine veterinarian!

Most vets would agree that the smaller the testicles when they are removed, the less chance of a haemorrhage (continual bleeding for more than 15 minutes) and other complications.

Although stallions (male horses over four-years-old) can still be gelded, they may retain much of their learned stallion behaviour (especially if they have already covered mares) and there is a greater risk of complications following the surgery.

What is a Cryptorchid?

777_equine_laparoscopyA young colt whose testes have not fully descended into the scrotum is called a cryptorchid. It is possible for one or both testicles to stay up in the canal or abdomen and never descend into the scrotum. These colts can still be gelded, however it is a more complicated operation. In the past, the vet had to open the horse’s abdomen, which is a major surgery, however now the vet is more likely to use ‘keyhole’ surgery involving two holes. One hole will be used for the laparoscope (a flexible tube with a camera and light on the end), and the other hole for the instruments. The vet will be able to see inside the horse on a monitor, which is connected to the camera. The horse is sedated but standing through this procedure, as shown in this photo.

Horses that have been gelded but still have a non-descended testicle or part of a testicle left behind, or stallions that have both testicles retained inside, are called ridglings or rigs. They are usually infertile because of the higher temperatures inside the horse, however they still exhibit all the same stallion behaviours.

Preparing for the operation

Your horse should be in good health (no colds or diarrhoea), and preferably in good body condition (not too fat and not too thin).

He should also be up-to-date with his tetanus vaccination, however if he isn’t, your vet will give him both the tetanus toxoid and a tetanus antitoxin injection on the day. Even if your horse is immunised your vet may still give him a ‘booster’ injection, just to be safe (see ‘Tetanus’ article for more information).

After the operation

Your vet will probably give him an antibiotic and anti-inflammatory injection as well as the tetanus injection(s). You may also continue with a course of anti-inflammatory medication in your horse’s feed. Always follow your vet’s instructions.

You should place your horse in a small yard or stall for 12 to 24 hours for observation to ensure the wound is clotting (no haemorrhage). You want your horse to move around but not have so much space that they canter and disturb the wound. If you horse is in a stable your bedding should be fresh, clean shavings or straw.

After 24 hours you can move him out to a small paddock, well away from mares (it can take up to 6 weeks before stallion behaviour and fertility subside). If you don’t have these facilities, keep him in a yard but make sure it is kept clean (clear manure and urine if possible, 3 to 4 time a day).

779_Lunge2Most vets suggest that you should move your horse around the day after surgery to minimise the swelling. You can exercise him on the lunge (slowly) or hand-walk him for 15 minutes 2 to 3 times a day. Exercising should continue for at least 2 weeks, when healing should be complete. When to exercise, how much and how often will depend on your horse’s recovery and whether or not he has had any complications. Always ask your vet and follow their instructions.


Castration is one of the most common surgical procedures that equine veterinarians perform. Although the procedure is relatively simple, it does come with a number of possible complications. It has been estimated that 25% of castrations encounter some form of complication.

Swelling – This is the most common problem and can be caused by the wound not draining, not enough exercise, surgical trauma, or infection. Gentle exercise, cold water or compresses (don’t hose directly into the wound), and administering non-steroidal anti-inflammatory drugs will probably help to reduce the swelling, however an infection may require a course of antibiotics.

The most important thing is to let the wound heal from the inside first. If the wound closes up too soon it may trap fluid in the internal cavity, which has been left behind after the testicles are removed.

Haemorrhage – The next most common complication is excessive bleeding, either internally or externally. This can occur during or just after the surgery. It can even happen several days later. You should expect some bleeding, however if it doesn’t stop after 15 minutes it is considered excessive. A true haemorrhage from the spermatic chord can be life-threatening, so call your vet immediately.

Eventration/Evisceration – This is the most dangerous complication but thankfully it is not common. Eventration is when something inside the abdomen, such as the intestines or other tissue, pushes through the site of the incision. The first 24 hours are critical, which is why you keep your horse under close observation during this time. It can occur later, however it is not common. If you see anything hanging from the wound, keep your horse quiet and call your vet immediately – it is an emergency.

Other complications can occur weeks or months after castration, these can include infection in the spermatic chord, or fluid swelling in the scrotum. The best thing you can do is to keep an eye on this area by making it part of your regular horse check.


Comment: After a couple of experiences with stallions, in my younger years, I have never had any desire to keep a stallion on our property.

The first was in a Racing Stables, when one of the grooms walked a mare past the sand roll. What he didn’t know was that the horse in the sand roll was a stallion. All I could hear was roaring, and when I turned around the stallion had pushed through the brick wall with his chest and was attacking the groom.

The second experience was on a Thoroughbred and Standardbred Stud. It was breeding season and when the owner’s son went in to feed one of their stallions he picked him up by the thigh muscle and took off through the yard and across the paddock before he dropped him. Needless to say there was an emergency dash to the local hospital to stop the bleeding and try to save his leg.

I’m not trying to scare you, and not all stallions are this aggressive, however anyone who deals with stallions professionally knows that you can never take them for granted. A friend of mine breeds AQH’s and she has a terrific stallion and several colts, which she handles. Even though she is always calm and cool around them, I know she has eyes in the back of her head.

When I bought Dioso as a 2 year-old colt he came off the truck full of hormones. It seems that he had spent 7 hours side by side with some mares, and he wasn’t in a good mood. As he came down the ramp he was biting, rushing and roaring, so as soon as he was in the yard I rang the vet and said ‘Can you be here tomorrow?’ I was going to leave him a couple of days to let him get over the long journey, but I had no intention of risking my family or myself.


The above information is only general in nature. Please discuss all procedures, options and problems with your veterinarian.

Update: News Articles

NERN to Trial Gelding Clinics in California

First published here: 15 February 2011

The National Equine Rescue Network (NERN) is hoping to castrate 100 or more horses across California through 2011. This is a trial that may result in a national roll-out of the programme.


The main aim is to reduce the number of ‘unwanted’ horses that are putting an unaffordable strain on welfare organisations across America. The programme is intended to help owners who can’t afford to castrate their horses.

Shirley Puga, founder of NERN, said ‘The current economy has created a greater number of displaced horses and this trend will likely continue for at least the next few years. By gelding colts and stallions, we can help reduce the number of new horses coming into the world during these trying economic times. Hopefully, proactive measures such as these will go a long way towards alleviating this problem”.

The gelding clinics will be a joint effort between NERN, local non-profit equine welfare organisations and veterinarians who volunteer their time.

The first clinic will be held in February at Huntington Central Park Equestrian Centre, located in Huntington Beach, California. They then intend to hold a clinic once a month and publish the details 30 days before each clinic.

NERN is a non-profit organisation and is accepting public donation to help with the costs of these clinics. Anyone interested in helping with a donation, or who needs help with their horses, should go to the NERN website.

Comment: This is a great idea and we hope that it is successful. Organisations in other countries should keep an eye on the success, or otherwise, of this programme, and maybe think of implementing a similar strategy.

Governments should also think about this approach when it comes to cats and dogs. If you have ever visited a pound you will understand the unnecessary suffering that occurs when we allow indiscriminate breeding.