It’s hard to know how an unfamiliar dog will react to your attempts to become his leader; if you catch a very self-protective dog off guard, he may bite. It doesn’t happen frequently, but don’t take the chance, and make your assessments in other ways instead. He’s going to be a little bit out of sorts when you first take him out of his cage. Give him some time to get used to you and to work out his excess energy. Don’t make loud noises or sudden moves; just let him sniff and greet you, and then take him somewhere where you can really get acquainted.

Never grab an unfamiliar dog; he may interpret this as a threatening gesture and respond by snapping. If you’ve brought your kids with you to the shelter, ask them not to touch the dog until he’s gotten accustomed to you and until you know that he is trustworthy.

Crouch down and pet him and play with him. Does he accept and enjoy your affection, or does he act suspicious of you or ignore you altogether? Does he trample and nip you, or does he avoid you? Look for a dog who plays and cuddles with you enthusiastically but not obnoxiously or fearfully. Take a walk around the room. Does he trot after you, or does he seem relieved to see you go? He should follow you happily without attacking your legs. If you have a toy, toss it for him. Does he show interest, or does he turn up him snout at your attempt at a game?

Keep petting, talking, and playing with him. If he growls or snaps at you or curls his lip, move on to another dog. Unless you’re an experienced dog trainer, you don’t want to mess with an aggressive dog. If he doesn’t appear dangerous but is nevertheless very rough or mouthy, he still may be too dominant for you.

If he slinks around and avoids looking at you, he’s probably a submissive dog who will need a lot of positive reinforcement. Some dogs may cower or shake when you try to pet them; many interpret this as a sign that the dog has been hit or beaten. However, adult dogs often shrink away from human hands simply because they were not properly socialized and have never gotten used to being touched and petted.

If a dog seems wary of your touch at first but begins to accept your affection after a few minutes, chances are that he’ll be able to come out of his nervousness pretty quickly with good training and lots of love. Bur if he remains nervous and terrified, it’s probably going to be a real challenge to turn him into a happy and comfortable pet, and he’s better left to someone who’s had lots of experience working with undersocialized or abused dogs. If he’s lethargic and draggy, there’s a good chance that poor health is to blame. Look elsewhere. You don’t want to adopt a dog who may be sick. Be on the lookout for a dog who’s cheerful, responsive, and confident.

Do you have fun playing with him and paying attention to him? Often, when owners who are having troubles with their adopted dogs, their biggest problem seems to be that they just don’t like their dogs very much. Do not adopt a dog if you’re not crazy about him! Spend as much time as you need to get to know as many dogs as you can; make more than one visit if necessary. But don’t forget that a dog who catches your eye one day may be adopted by someone else or even euthanized the next, so you’ll have to judge for yourself how long it’s safe to wait.