A trained veterinary nurse or technician should hold your horse for the veterinarian. Although sometimes this is unachievable due to emergencies or staff shortages etc. The veterinarian has to trust you to hold and restrain the horse safely. This can be a lot of pressure and responsibility so if you do not feel comfortable, let the veterinarian know.
When holding the horse, it is always safer to stand on the same side of the horse as the vet so the horse can move away from you if necessary. Never stand directly in front of a horse as this is just as dangerous as standing beside one. Even when a horse has been sedated standing in these locations can still be very dangerous as the horse can still react to pain or other stimuli and injure you if you are in the way.
People often tend to relax around a sedated horse and let their guard down as they assume the horse will not move. Even horses that are sedated to the point that they can barely stand can take fright at something and cause severe injury. Stay alert if your vet is working on a sedated horse, don’t make any fast movements and don’t surprise a horse without lettingthem know that you are in their area. This can be achieved by talking to the horse before touching and letting him/her know you are near him/her. Another tip is to stay as calm as possible during an emergency situation. When a horse is afraid and thus unpredictable so it is vital for the handler to be as calm as possible. Being calm is not always easy but it can help keep your horse calm and make treatment easier for everyone.