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  • Castration

Castration is a routine procedure most commonly performed in young colts in order to prevent unwanted breeding and aid management.

There are three main methods of castration, the decision as to which is most appropriate should be discussed with your vet as the choice is dependent upon a number of factors including age and size of animal, temperament and previous history:

  • Open castration which is usually performed standing with the incisions left open.
  • Open castration which is performed under a short acting general anaesthetic in a field setting. (This is usually reserved for smaller ponies or unhandled colts who cannot be castrated standing.)
  • Closed castration under general anaesthetic which is performed in an operating theatre.

Open Castration

Open castration is the most commonly performed method of castration and can be performed either standing, under heavy sedation and local anaesthetic, or under a short general anaesthetic. Standing castration is only possible in quiet, well handled horses, and is not safe to undertake in small ponies or horses that are difficult to handle. Guddling around between the hind limbs of a colt who is reluctant to give up his manhood can be quite a dangerous job!

Open castration under general anaesthesia is most commonly undertaken in ponies. Although all anaesthetics carry a small risk, this is minimal in healthy horses. In most cases two incisions are made, one over each testicle, and these are left open post operatively. This allows free drainage of blood and serum that normally forms at the surgery site.

Closed Castration

This involves a general anaesthetic and the procedure can only be performed under sterile conditions in our operating theatre. The skin incisions are closed (stitched) following surgery. This method is generally recommended in older horses whose testicles and cord are more mature/larger. The closed method reduces the risk of haemorrhage.
As the incisions are sutured closed they are unable to drain as well as open castrations and as a result these horses often develop significant swelling of the castration site.

Tetanus prevention

If the horse has not already been vaccinated for tetanus, he will need to be given temporary cover at the time of the castration. Check with the vet before the operation is performed as to what is required.


It is helpful if you have your horse’s passport or breeding papers available at the time of castration, so that they can be modified to confirm that he has been gelded.


Gentle exercise should be encouraged to promote drainage and prevent swelling of the scrotum. Ideally, this should be achieved by turning the horse/pony out into a small dry paddock where he can move around quietly for at least a week. If your horse/pony is stabled then he should be walked out at least 3-4 times daily for 10-15 minutes to decrease swelling and improve drainage.

With open castrations, the wound will be left open to allow drainage. Dripping of blood from the wound is normal, and this may continue for several hours after surgery. The legs should be washed or hosed down as necessary but it is usually not necessary to clean the wounds themselves. If blood streams from the wound or there is bleeding for more than 24 hours please contact us. The scrotum may remain swollen for up to a week; again this is normal and the swelling should start to decrease after this time.

All horses are given a dose of antibiotics and pain relief for the procedure. Your vet may or may not consider it necessary to prescribe a longer course of antibiotics. Further painkillers (usually ‘bute’ powders) can be beneficial to help the horse or pony feel better after the operation, and move more freely; these may be prescribed by the vet who performs the surgery for a few days.


Castration (gelding) is one of the most common operations we perform and like any surgical procedure, complications may occur in spite of the procedure going smoothly.

This is the most immediate and common complication and can be life-threatening depending on the extent and duration of bleeding. Bleeding after surgery is often minimal with intermittent drops of blood which spontaneously stop within minutes. However, if the drops cannot be counted then prompt veterinary attention should be sought. The bleeding may come from the testicular artery (which may have been ligated during the castration procedure) or from one of the blood vessels in the scrotum which are not ligated during surgery. Depending
upon the level of haemorrhage, either the scrotum will be packed with sterile swabs or the bleeding blood vessel will require ligating (tying off).

A degree of post operative swelling is normal and is not considered a complication however excessive swelling accompanied with stiffness
should arouse suspicion of infection. We normally recommend a course of anti-inflammatories (bute) which would help to control post operative swelling and pain. Modest exercise in the form of paddock turnout will help to minimise swelling post operatively. Excessive swelling or stiffness may indicate infection (see below).

Open castration is often termed a clean rather than sterile procedure as it is performed in field conditions where it is hard to reproduce the
sterility of an operating theatre. Antibiotics are commonly administered following castration to reduce the risk of infection. The placement of a
ligature (stitch) around the testicular artery during surgery has the advantage of reducing the likelihood of haemorrhage but this does increase the infection risk due to the presence of a foreign material within the body which can act as a focus for infection. Infection causes swelling and discharge from the surgical site and a stiff gait indicative of pain. The temperature may be raised and appetite may be reduced. For minor infections, antibiotics combined with manual opening of the incisions usually resolves the infection. More serious infections can need a further surgical procedure to remove infected tissues.

Occasionally a soft, fluid swelling may be noticed within the scrotum of a gelding which is termed a Hydrocoele. This is essentially an accumulation of fluid within the vaginal tunic (the membrane that covered the testicle) which is more common following open castration.
These do not normally cause any problems but can be corrected surgically if desired. Hydrocoeles may be detected at pre-purchase examinations when a blood test may be required to confirm that no testicular tissue remains.

Occasionally a small amount of fascia/fat may protrude from the incision particularly if there is post operative swelling. Unless the amount of tissue is very small, this will probably need trimming under sedation. The more serious form of herniation occurs if small intestine is able to pass through the inguinal ring (a small gap in the body wall through which the testicle descended). This normally occurs following a standing castration and is associated with an abnormally large inguinal ring. Treatment of this is an emergency and involves replacing the intestines within the abdomen within an operating theatre. Correction of this problem can be diffcult and may prove fatal but thankfully is rare.