Colt Castration – advice to owners.
Castration is a surgical procedure performed by a veterinarian that is defined as the removal of the testicles of a male horse.
Safety and management are often good reasons to justify castration. If a colt is left entire it is usually impractical/impossible to run them in company, with either mares, geldings or other stallions. Stallions are constantly under the influence of testosterone (hormones) and can be aggressive and potentially dangerous to other horses and people.
Castration will make life easier all round, unless you plan to breed. If castration is delayed, it can be more expensive as the cost of surgery can be much greater.
Before undergoing castration, the colt should be in good health and up to date with worming and vaccinations, particularly tetanus.
Please be aware that a colt should be well-handled prior to the procedure, whichever technique is used. As a vet, there is nothing worse than realising that a colt has never worn a head-collar! This is dangerous for everyone concerned, as well as very stressful for the colt and ultimately more costly.

The procedure
The procedure can be carried out under sedation and local anaesthesia in a standing position or through general anaesthesia.

Factors which influence the choice of method:

  • Age (e.g. a mature adult has a higher risk of complications)
  • Size (e.g. a Shetland pony is too small to castrate in the standing position)
  • Breed (e.g. Shires are an increased risk of general anaesthesia, donkeys increase risk of haemorrhage)
  • Temperament (e.g. a horse can still kick despite heavy sedation, making the procedure impossible)
  • Maturity (e.g. testicles must have dropped sufficiently so that everything is easily within the surgeon’s reach; mature stallions are at increased risk of haemorrhage)

Standing open castration: This is the most commonly used method. The surgery is performed under heavy sedation and local analgesia thus removing the risk of a general anaesthesia. There is a relatively high complication rate (approx. 20%) with standing castration – although the majority of these are minor, primarily post-operative swelling and infection. The standing method is cheaper. The major risk factor is herniation of gut through the castration wound which can be fatal.
Closed castration under general anaesthesia: This is the most suitable method for stallions over 4 years of age. There is an associated risk of a general anaesthetic but there is a much-reduced risk of haemorrhage and herniation of gut. Surgery is normally performed at the clinic.

When is the best time to castrate a colt?
A colt can be castrated at any age. It is traditionally done as a yearling, but we have increasingly castrated at a much younger age. We now routinely castrate at 5 months of age while still on the dam (ideally about a month prior to weaning). There is no evidence that foals left entire, develop any differently from those castrated early. If only one testicle is present (a ‘rig’), the owner may decide to wait a bit longer and hope that the missing testicle will eventually descend (it may or may not). A rig may be castrated in hospital under general anaesthesia.

Colts can be castrated at any time of year; however, they should ideally be castrated either in the spring or autumn, in order to avoid the flies of summer and the deep mud of winter.

Post-operative care:
Castration is generally regarded as being a routine procedure, and in the vast majority of cases it is both straightforward and uncomplicated. However, it should not be forgotten that it is an invasive surgery and occasionally complications will occur.

Following castration, horses may receive a tetanus toxoid booster (if vaccinations are current) or both tetanus toxoid and a tetanus antitoxin injection if the colt has never been vaccinated. Your vet will administer antibiotics and anti-inflammatories to your colt at and following surgery. Advice varies slightly with individual circumstances. If flies are still in season, it is a good idea to apply an insect repellent immediately after the castration around the surgery site but not on the wound.

We try to castrate most colts in the morning. We recommend that the horse be placed in a small paddock or box after surgery for 12 to 24 hours for observation and to ensure adequate clotting. If the horse is kept in, the bedding should be clean and fresh.

Beginning from the day after surgery, if kept in, the horse should be exercised at a walk or on a horse walker for at least 15 to 20 minutes three times a day to avoid swelling and stimulate drainage of any post-surgical fluid that may have accumulated in the swollen scrotum. Exercise should continue for about two weeks or until healing is complete. There may be some swelling of the scrotum (up to twice its normal size) for 3 – 4 days post op, however this should start to decrease by the end of the first week.

Post-surgical complications can occur.

  • A general anaesthetic in any horse carries an element of risk, but the castration procedure in itself carries less risk, when compare to the standing method, in older/mature stallions.
  • The most common complication is excessive swelling of the scrotum that can extend down into the sheath. If the wounds seal too quickly, fluid can be trapped, giving the impression that the testicles have returned! These horses should continue to be lightly exercised, but may require sedation for drainage of the fluid. If increased exercise does not resolve the problem, contact us.
  • Bleeding commonly occurs. If there is a slow drip from the wound, over the first 24 hours – this is normal. If it exceeds a fast drip or does not slow down over a few hours, ring Walker Equine Vets immediately.
  • In rare instances, following standing castration, the intestines may protrude from the incision. In such cases the animal is usually obviously unwell and uncomfortable. This usually occurs within a few hours of the surgical procedure but can happen days later.

If this occurs, consider it as a true emergency and contact Walker Equine vets immediately on 01823475208.

  • Infection can occur in the wound. This most commonly happens several days after castration. Antibiotics may be required, speak to us if you think this has happened. The horse may develop an uncomfortable swelling and may be reluctant to move normally.
  • If the horse shows any signs of colic or develops a temperature, contact Walker Equine Vets immediately.

Important considerations after castration:
A colt CAN be fertile for a short while after being gelded, so he should not be turned out with mares for at least 8 weeks following castration

The ‘stallion like’ behaviour can continue for up to 6 months, but rarely more. In young animals it is likely to reduce much sooner. The length of this period depends largely upon the age of the horse. Mature animals can continue to show strong stallion-like behaviour, especially if they have previously covered mares.