Depending on the area that you are in, there will be no wondering about if they belong to someone. If there is a possibility of them belonging to someone, I ask them if they have a dog that looks like the ones I have encountered. If they don't belong to anyone in the area, or there is no one in the area, they go down. Besides, it doesn't take a trained eye to tell the difference between a healthy pet and a feral dog. One of my hunting mentors once told me, "You know how you keep it a secret when you see a huge buck? Well, if a dog keeps ruining your hunting trips, kill it and practice that same kind of secrecy."