T here are four basic types of aggression: fearful aggression, dominance aggression, possessive/protective/territorial aggression and redirected aggression. Each of these types of aggression are demonstrated by similar actions such as growling, biting, baring teeth, refusing to move or any other behavior meant to harm or intimidate another dog or human.

Each of these kinds of aggression is complex and the consequences can be serious. Therefore, a professional animal behaviorist should address aggressiveness. Find an animal behaviorist or trainer who will work one-on-one with you and your dog.

From the dog’s perspective an aggressive response is always warranted. However, a dog’s aggressiveness is almost never acceptable to people. The key to solving aggressiveness is to identify the type of aggression and the triggers and then retraining the dog to trust his or her human companion to be in control of the situation.

Let’s learn a little more about each type of aggression:
Fearful Aggression
This type of aggression occurs when your dog perceives that he is about to be harmed. Whether or not this is the intent, his perception drives his response. For example, another dog runs toward your dog. You perceive this as a playful gesture, but your dog perceives it as a threat. Or, you stand suddenly from the couch and your dog reacts aggressively to your sudden movement.

Dominance Aggression
Dogs are always working out a “pack” order or “dominance hierarchy”. Your dog considers you, other dogs and other pets part of her pack. Everyone’s role in this hierarchy must be clearly defined for your dog to feel confident in her place. It is up to you to establish the hierarchy and to establish yourself as the leader. However, some dogs take the role of setting pack order onto themselves. If your dog perceives her ranking to be higher than yours, she will take it upon herself to be sure the pack order is maintained. This means that if she feels challenged, she will defend her place at the top. You may have simply been reaching for her collar, but she perceived it as a challenge. Or your child may have been simply looking her in the eye, but she perceived it as a challenge. The neighbor’s dog may have appeared to be greeting your dog, but it may have been a challenge or at least perceived as one. As you can see, this is a complex issue. We again reiterate that you should consult a professional trainer to work with you and your dog privately to overcome these issues.
Here are some things you can do to establish that you are the pack leader:
Always go through doorways first. Make your dog wait.
Do not let her onto the couch or bed. These are places reserved for the pack leader.
Greet other dogs and people first, showing your approval. Do not let your dog greet first and determine your reaction based on his.
Do not play tug-of-war. Whenever the dog wins, he is establishing his dominance over you.
Do not let your dog stand over you and do not place yourself physically lower than your dog.
Do not let your dog stare you in the eye. Don’t break your gaze, but distract her from hers with a toy or a command.
Teach your dog that nothing is free. From feeding to putting on a leash, you should make your dog perform a command. Even making him sit will do. This shows you control every situation.

Possessive/Protective/Territorial Aggression
This kind of aggression is in response to the threat of loosing a valuable resource.
Possessive aggression is often related to food and toys. Protective aggression is a dog’s defense of his pack – people and dogs. Territorial aggression occurs when your dog perceives a threat to “his” yard or space.

Redirected Aggression
This form of aggression is common but hard to understand. If a dog is stimulated it will react by acting aggressively to a person or animal near by. For example, both of your dogs are looking out the window when a neighbor walks by with his dog. Both of your dogs bark and are stimulated. One of your dogs suddenly turns on the other and attacks him. Or, you scold your dog for misbehaving and he tears out of the room after your cat.

What will individual training do?
The basic goal of working one-on-one with a trainer is to provide a controlled environment while raising the dog’s threshold. Each dog differs in his or her tolerance of threatening stimuli. Modification techniques will raise your dog’s tolerance over time. An experienced animal behavior specialist understands best how to address each of these types of aggression while achieving maximum results for your dog.

What can I do?
Aggression is serious and dangerous. Your main objective should be to keep all people and animals around your dog safe.
Take your dog to the vet to find out if a medical cause can be determined. This is especially important if the onset of aggression is sudden.
Hire a professional. The problem will not go away and it is most likely that you do not have the knowledge of animal behavior necessary to fix the problem.
Be safe. Use confinement, separation, and supervision to avoid conflicts. Restrict your dog’s movement in the house. And when venturing out with your dog, you may want to consider a muzzle.
Try to identify triggers and avoid them.
Spay or neuter your dog! Hormones are a serious factor in aggression. Eliminating hormones can eliminate many challenges.

But don’t…
…punish your dog. This may make things much worse for a dog who is aggressive out of fear. It may be seen as a challenge to the dominant dog again escalating the problem.
…encourage aggressive play. Don’t intentionally get your dog excited when you hear a noise outside. Don’t say things like “go get ‘em”. Do not wrestle with, play tug-of-war with or otherwise make a game out of anything your dog may be able to “win” at.