The term “aggression” covers a range of behaviours in dogs. Aggression can have many different causes, such as protectiveness, fear, territorial instincts, frustration, pain, possessiveness of food and other valued resources, etc.
What aggression looks like.
Dogs use a large and complex vocabulary of body language to communicate different levels of aggression. Some examples:
Going still and stiff (“freezing”).
Deep-throated, threatening barking.
Lunging at someone or something.
Growling, snarling, baring teeth.
Snapping/nipping at various intensities.
Biting at various intensities.
(Canine body language is often so subtle or quick that owners miss the cues and swear their dog attacked without warning. This is rarely the case, though, and is another reason to call in a professional. See below.)
What causes aggression? It’s a natural response to perceived threats in all animals, including humans. Genetics also play an important role—we have bred dogs to protect our livestock and hunt prey, for example, and those instincts are present in our pet dogs. Mostly, individual temperament and under-socialization are the culprits in aggression cases.
What to do.
Get perspective. Aggression can be frightening and heartbreaking—and is certainly nothing to take lightly. You’re responsible and liable for your dog’s behavior, and safety must come first. At the same time, it’s important not to think of canine aggression as you would human aggression, with its implied volition. Your dog may be familiaris, but she is first and foremost Canis, subject to the hardwired responses of her species.
Take precautions. Closely supervise your dog and avoid situations that might trigger aggression. Is she aggressive toward other dogs? Stay away from dog parks and use a muzzle when you go out in public. Is she possessive of her toys and food? Restrict access to those things and leave her alone while she eats.
Consult your vet. First, you need to rule out medical conditions. Pain can make a dog irritable and prone to aggression, and anything from joint soreness to an ear infection can trigger a bite with few warning signs. Second, intact animals are more likely to display aggression of all kinds, so if you haven’t spayed or neutered your dog, talk to your vet about an appointment.
Hire a qualified professional. Aggression is complex and can be dangerous to work with, so behavior modification should only be carried out by a professional. Look for someone whose methods are based on behavioral science concepts like operant and classical conditioning, desensitization, and counterconditioning. Relevant certifications include Certified Applied Animal Behaviourist (CAAB), veterinary behaviourist (Dip ACVB), and Certified Professional Dog Trainer (CPDT).
Whatever you do, don’t punish. Physical punishment, including dominance-theory practices like alpha rolls, can make aggression worse. Scolding a dog for growling, for example, may seem appropriate to us humans, but doesn’t address the underlying reason the dog growled. If we succeed in quieting the dog, we have turned off the warning signal that told us how she felt, and next time, she might go straight to a bite.