Why castrate?
Colts are generally castrated for ease of management. If a colt is left entire it is usually impractical to run him with mares, geldings or other stallions, especially as he matures. Colts can become difficult to handle or even dangerous. They are sometimes castrated because of conformational problems. Less common reasons to castrate include retained testicles (cryptorchids), scrotal hernias or testicular tumours.
Horses castrated as foals tend to recover quicker while stallions castrated after maturity may take longer to recover and be more prone to some complications.
Horses to be castrated should be in good general health and have their tetanus vaccinations up to date. If there is any doubt regarding their tetanus vaccination history, they will require a tetanus anti-toxin (see our article on vaccination at www.totallyvets.co.nz).
Most horses are now castrated "down". This means a full general anaesthetic is given and the surgery is performed while the horse is lying down. Quiet, well-handled horses can be castrated while standing, using local anaesthetic and heavy sedation. Either way, a clean dry area is required in which to castrate the horse and fine weather makes this more achievable.
Castration can be further divided into "open" or "closed" castration, referring to whether or not a final layer of tissue over the testicle is cut or left intact.
In the field, open castration is used and the incisions are left open to drain.
Closed castrations require a longer anaesthetic and sterile conditions as the incisions are closed after surgery. This increases the cost considerably, but reduces the risk of complications such as haemorrhage, infection or herniation.
Immediately following surgery, turn the horse into a small, clean, grassy paddock. For the first 24 hours following castration, keep the horse in this restricted area to reduce the likelihood of bleeding (due to blood clots dislodging). After 24 hours, he can be moved into a larger paddock. The horse will need to be separated from mares for a further 3 weeks post-castration.
The first complication that may result from castration is excessive bleeding. The wounds may drip blood for 24-48 hours after the surgery. If individual drops cannot be counted, the vet needs to be called immediately. This may occur in the first 24 hours post-operatively even after appearing to be under control.
Evisceration may occur, where a piece of fat (omentum) that lines the gut, or more seriously a loop of bowel, may become exposed through the incisions. This is very serious and requires a vet immediately. The bowel must be kept off the ground, e.g. in a clean sheet wrapped around the horse's belly until the vet arrives. Evisceration can occur anytime in the first 48 hours following castration.
Swelling will normally be maximal at approximately 3-5 days after the surgery. Encourage the horse to exercise e.g. lunging, hand walking, gentle exercise or turning him into a paddock with company where he will move about. If you notice that he is standing around, then he will need to be forcibly exercised to help prevent excessive swelling.
Infection may develop after 5-7 days. The horse may have swelling and discharge around the incisions or be lethargic and not eat. The vet should be contacted as the incisions will need to be reopened to drain and antibiotics and anti-inflammatories may be required.
If you have any concerns, or would like to book one of our dedicated equine vets to castrate your horse, please do not hesitate to call Totally Vets.
