Being able to tell when your dog is going to bite is an important skill. While dogs may vary to some degree in the behaviors they show before biting, most will exhibit some combination of the following: direct staring, pulling, barking, growling, snapping, and lunging forward. The extent to which your dog engages in these behaviors depends on his individual personality, prior experiences, and the threatening stimulus.
For the sake of simplicity, let’s assume that your dog is exhibiting this wariness toward strangers he encounters during walks. To minimize the chances that he will bite, we suggest walking him on a head halter so you have more control if he does react aggressively. It’s also a good idea to always carry his favorite treats with you; should you see a stranger approaching, you can use the treats to get his attention and distract him until the stranger passes and is no longer in sight. In time your dog will associate the presence of oncoming strangers with good things—food! The main thing to keep in mind is to never put your dog in a situation in which is he uncomfortable and has the opportunity to bite.