Why does my dog bite people?

A common cause of aggression is actually fear. To make a scary situation or person go away, the dog is resort to offense is the best defense strategy (snapping, growling, biting) To resolve this you'll want to use counter-conditioning/ desensitization techniques and train behaviors that you desire and train the dog's impulse control.

Before you can fix this issue, it's helpful to try to determine the cause of this behavior.

Is your dog...

Under the age of 1?

Biting people with his tail wagging?

Bowing down on his front legs before jumping up and attacking?

If you answered yes to any of the above questions, it is likely that your dog thinks he is playing and does not realize that his behavior is harmful. Some useful approaches are to seek out a trainer/taking training classes, to put him in a time out whenever he bites, to redirect his attention to a toy when he goes to bite, to reinforce positive behavior with a treat, and to make a yelping sound while simultaneously avoiding jerking your hand or body part away when he bites (this causes him to think you are still playing).

If this doesn't appear to be the case, consider the following.

Is your dog...

Adopted and you're unsure of his background?

Older in age?

Extremely attached to you?

Largely unsocialized with other humans and dogs?

If this sounds more like your dog, he may be protecting you. Often, when dogs are from a one-person or two-person home with minimal exposure to other people, they become fiercely loyal to their owners and see other people as a threat because they don't know how to act. In such a case, some possible ways to combat this behavior are: seek out a trainer/take a training class, use a muzzle (SOFT MESH ONLY -- DO NOT USE BASKET MUZZLES ON DOGS AS IT CAN INTERFERE WITH BREATHING AND INCREASE ANXIETY), reinforce positive behavior with a treat, introduce dog to people in a neutral, non-territorial setting (such as the park or the sidewalk), utilize time-outs when negative behavior is displayed, and redirect attention when aggression begins.

First of all, it's important to distinguish whether this is actual biting or just being mouthy-- which is normal for puppies. Mouthing means they have a "soft mouth" where they are not actually biting down hard, they are moreso just playing. This doesn't mean that behavior is acceptable. The best way to prevent it is to cease all play and attention when this happens, and give the dog an alternative that is acceptable to chew on and play with.

If your dog is actually biting people, find a trainer in your area who specializes in this ASAP. They will work with you to identify what is triggering the dog and a plan of action to correct the behavior. It's not something that you can usually solve by reading a few articles online-- this is a serious issue that needs a professional.

Dogs bite for quite a few reasons. They feel stressed, scared, startled, threatened, etc. They may be trying to protect a favorite toy, food, or anything else valuable to them.

If your dog is already biting people, hire a personal trainer. Seriously. You have a lot of work to do if he has already started biting, and no amount of Googling or community advice is going to give you the amount of help you need. He can unlearn the behavior, but you need professional help.

That said...

Make sure your dog understands you are the alpha. Always make sure you are entering the house first; you can even have him make him sit and wait before entering and leaving the house. If he barks at the window or door, calmly walk over, look at what is outside, tell him "good, thank you", and walk away. This way, he's alerting you to something, and you're showing you're not concerned, and you've taken care of it. Teach him the "Leave it!" command. Start with toys and food. I have my dogs "sit" and "leave it" for every single meal until I release them to eat. I also make them sit before giving them any treats or toys. Don't let him jump on you or furniture uninvited.

Use walks as training opportunities. All of the walks. Carry training treats on your walks. Keep him close to you. Watch him carefully. Every time he looks at you say "good" and give him a treat. This teaches him to follow your lead. If you see someone approaching, start giving him treats to get him to associate people approaching with good things. Check your emotions. He can sense what your reaction is, so if you start getting nervous or anxious because you're anticipating his reaction, he'll pick up on it and interpret it as an approaching threat. Move to the side and stand in front of him with your back to the approaching person. Have him sit and give him a treat. Continue giving him treats while he sits, and keep standing between you and the approaching person. Continue giving him treats until the person passes.

If you are using a retractable leash, stop. They encourage pulling and give control to your dog instead of you. They are horrible inventions.

Good luck!