Judas horse is term used to describe a domestic horse which has been trained to lead wild horses into a trap. A judas horse is often used when capturing wild mustangs. Once the wild horses are coerced into an area near the trap, the Judas horse is released. Its job is then to move to the head of the herd and lead them to the trap. Already confused and looking for direction, the wild horses instinctively follow the leader into the trap.