A trained veterinary technician or assistant should hold your horse for the veterinarian. However, sometimes this is impossible during emergency situations, and some vets do not have technicians available to help. The veterinarian has to trust you to hold the horse. This is a lot of responsibility so if you do not feel comfortable, tell the veterinarian.
When holding the horse, it’s much safer to stand on the same side as the vet so the horse can move away from both of you if necessary. Never stand directly in front of a horse as this is just as dangerous as standing directly behind one. Nor should you ever trust a tranquilizer; even though the horse may seem very sedated, he can still react to pain or other stimulus and injure you severely. People tend to relax around a sedated horse and let their guard down because they assume the horse will not move. However, I have seen horses so sedated they could barely stand and yet blow up and cause severe injury. Stay awake if your vet is working on a sedated horse! Also, don’t surprise a horse without letting him know you are in the area, especially if he is sedated. You can do this by talking to the horse before touching and letting him know you are near him. Another tip is to stay as calm as possible in an emergency situation. The horse is afraid and thus unpredictable so it is important for the handler to be as calm as possible. Being calm is not easy, but it can help keep your horse calm and make treatment easier for everyone.