Why does my dog bite me?

There are several possible reasons for why this is happening and age can certainly play a factor. If it's a puppy, this is pretty common and not necessarily a sign of aggression. When puppies play with each other, they use their mouths, a lot. So when they play with you, they assume they can do the same until trained otherwise. A stern "no" when this happens, followed by providing an appropriate item to chew on/bite and then rewarding the desired behavior, should do the trick. If this is an older dog, it's more likely to be a behavioral/fearful response. Pay attention to what the environment is like when this happens. Is it always when your dog is on the leash? Some dogs become aggressive when restrained. Is it always around its food? It may have some guarding tendencies. Is it happening when you aren't giving him/her enough attention? Maybe it needs more exercise. Outside of behavior, the one other reason your dog will start biting is pain. If your dog is painful for whatever reason (skin infection, trauma, neurological distress), biting is a knee-jerk reaction; he/she is telling you that something hurts and they don't feel comfortable being touched. Outside of typically puppy-biting, a veterinarian should be consulted to diagnose the cause and provide the appropriate consult or treatment.