Have you ever seen an adorable dog walking down the road and couldn't wait to pet it? If so, you are not alone. However, even if the dog looks as friendly as ever, you shouldn't pet it without proper warning. If you don't properly greet a dog before petting him, it can result in snaps or growls, according to Slate.com.

Before you pet someone else's dog, it's a good idea to squat down to his level and let him make contact first. Instead of facing the dog directly, turn slightly to your side. If you allow the dog to approach and sniff you, he will feel less threatened. It's okay to reach your hand out, as long as you do it slowly and low to the ground. 

If the dog seems shy or scared, Vet Street recommends looking away for a few minutes, pretending to ignore him.

When the dog seems comfortable enough, you can pet him. However, you shouldn't just pet the pooch anywhere. If you, for example, pet the dog on his head, ears or tails, he may feel uneasy. It's better to pet a dog on the chest, neck or shoulders. As you are petting him, move your hand in slow and gentle motions.

If the dog happens to roll over on his back, it's not an indication he wants his belly rubbed. A dog will roll over in this position when he feels scared. Never put your face near a dog's head if you don't know each other well.