Our approach to gelding or castration of male horses includes general anaesthesia so the procedure is done with the horse lying down. In our experience, this is much safer for the veterinarian and horse owner (compared to castrating a standing horse) and is no more dangerous to the horse with the modern anaesthetic drugs that we use.
We begin with a thorough physical examination of the horse. Assuming there are no abnormalities detected, we give the horse a premedication to relax the horse which also serves to reduce the amount of anaesthetic drug required.
Once the horse is quite sedate, we administer the anaesthetic drug. When the horse is lying on the ground, we cover its face and tie the upper leg back.
Then we perform the castration using emasculators to clamp and cut the blood vessels and spermatic cord. We give antibiotics and tetanus prevention while waiting for the horse to wake up. Once the horse is standing, the job is done.
If we cannot palpate both testicles, we will suggest referral to a specialist equine centre. The surgery to locate a retained testicle inside the abdomen can be very extensive and involved and we would not advise that it be done in a paddock.