[header] How to stop your dog from biting other people [title] Distinguish between aggressive or playful biting. [step] Most dogs and puppies engage in mouthing, nipping or play biting, which is normal. If this is the case, your playful dog will have a relaxed body that isn't tense or aggressive. 
When he nips or bites, the puppy or dog won't show teeth or bite down hard. However, if your dog is aggressively biting, his body will be stiff, he'll show his teeth, and he'll bite quickly and hard.