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Aggression

Aggression is the most common behavior problem in dogs and is the #1 reason pet parents reach out for help from a professional.

What Is Aggression?

The term "aggression" encompasses a wide variety of behaviors. Aggression is used by virtually all species, including humans, for different reasons: to guard their territories and resources (such as food); to protect their family groups & offspring, offspring; and to keep the peace in their social groups. To say that a dog is “aggressive” can mean a whole host of things. Aggression encompasses a range of behaviors that usually begins with warnings and can culminate in an attack.

A dog that shows aggression to people usually exhibits some part of this sequence of behaviors:

Becoming still, rigid
Threatening-sounding guttural bark
Lunging forward at the object of its aggression, without contact
Mouthing, as though to move or control the person, without applying the pressure of a true bite
Muzzle punching: literally punching the object of its aggression with its nose
Growling
Baring teeth
Snarling
Snapping
Nipping that leaves no mark
Quick biting that does leave a mark / tears skin
Biting with enough pressure to cause a bruise
Biting that causes punctures
Repeated biting in rapid succession
Biting and shaking

Dogs do not usually follow this exact progression, and sometimes several behaviors can be exhibited at once. Many times, pet parents don’t recognize the warning signs before a bite, so they perceive their dogs as suddenly, "unpredictably" biting. That’s rarely the case, but since it can just be fractions of a second between a warning and a bite, the warning signs can be easily missed.

Classification of Aggressive Behavior

There are many classifications of aggressive behavior. If your dog has shown aggressive behavior or you think she has the potential for it, take some time to evaluate the situations that have upset her.

Who did she get aggressive with?
What was happening at the same time?
When and where did it happen?
What was just about to happen to her when she showed aggression?
What stopped the aggressive behavior?

Learning the answers to these questions can help provide insight into why your dog showed aggressive behavior and will help you address the issue causing aggression.

The following are the "types" of aggression that dogs can exhibit:

Territorial: Some dogs will act aggressive with new people in their home, whether it's an intruder or just a guest
Protective: Dogs may show aggressive behavior when they think that one of their people or friends is in danger
Possessive: Many dogs guard their possessions from other dogs or people, from food to toys, whether or not they need to
Fear: A fearful dog can show aggression when they feel trapped or cornered
Defensive: Also motivated by fear, defensively aggressive dogs will show aggression even before they feel trapped or cornered, acting offensively
Social: A dog who believes she is high in status may show aggression with others aka alpha behavior
Frustration-Elicited: A dog who’s excited by something but is held back from approaching it can become aggressive
Redirected: Occurs when a dog is aroused by or displays aggression toward a person or animal, and someone else interferes: example
Pain-Elicited: An otherwise gentle dog can behave aggressively when in pain; this is why a previously gentle pet exhibiting aggression should be evaluated by a veterinarian to make sure there is no underlying physical cause for the aggression. Also, if your pet has been injured or is otherwise in pain, proceed handling her with caution.
Sex-Related: Intact male dogs will vie for the attention of females, and females will compete for access to a male. This is one of many reasons spay/neutering your pet is so important and beneficial.
Predatory: Some dogs show classic canine predatory behaviors, including chasing and grabbing fast-moving things (including small pets)

Family Members, Strangers or Other Animals

Determining whom your dog is aggressive toward is essential to understanding her behavior. It’s common for dogs to behave aggressively toward unfamiliar people. Some studies report that as many as 60 to 70% of all pet dogs bark threateningly at strangers and act unfriendly when around them. Aggression toward unfamiliar dogs is also widespread. It’s less common for dogs to direct aggression toward family members or other pets in the home. Most problematic are dogs who are aggressive toward children, especially children in the family. Not only is aggression toward children exceedingly difficult to treat because of safety concerns, the likelihood that a dog with this problem will ever become trustworthy is slim.

Some dogs are aggressive only to a certain category of people. A dog might be aggressive only with the veterinarian or groomer, or with the postal carrier, or with people in wheelchairs or individuals using canes and walkers. In some cases, it’s easy to limit a dog’s access to the people that upset her. For instance, if your short-haired dog dislikes the groomer, you can just groom her yourself at home. But in other cases, the targeted people are impossible to avoid. For example, if you have a dog who dislikes children and you live in a densely populated urban apartment building next to a preschool, it will be difficult to avoid exposing your dog to children.

Aggression toward people, aggression toward dogs and aggression toward other animals are relatively independent patterns of behavior. If your dog is aggressive toward other dogs, for example, that doesn’t mean she’s any more or less likely to be aggressive toward people.

Risk Factors

If you’re deciding whether to live with and treat your aggressive dog, there are several factors to consider because you, as the pet parent, are ultimately responsible for your dog’s behavior. These factors involve the level of risk in living with your dog and the likelihood of changing her behavior:

Size. Regardless of other factors, large dogs can inflict more damage than small dogs.
Age. Young dogs with an aggression problem are believed to be more malleable and easier to treat than older dogs.
Bite history. Dogs who have already bitten are a known risk and an insurance liability.
Severity. Dogs who stop their aggression at showing teeth, growling or snapping are significantly safer to live and work with than dogs who bite. Likewise, dogs who have delivered minor bruises, scratches and small punctures are less risky than dogs who have inflicted serious wounds.
Predictability. Dogs at the highest risk of being euthanized for aggression are those who give little or no warning before they bite and who are inconsistently, unpredictably aggressive. Dogs who give warning before they bite allow people and other animals time to retreat and avoid getting hurt. As counterintuitive as it might seem, it’s easier to live with a dog who always reacts aggressively when, for instance, every time you push him off the bed than a dog who does so only sporadically.
Targets. How often your dog is exposed to the targets of her aggression can affect how easy it is to manage and resolve her behavior. A dog who’s aggressive to strangers is relatively easy to control if you live in a rural environment with a securely fenced yard. A dog who’s aggressive to children can be managed if her pet parents are childless and have no friends or relatives with children. A dog who is aggressive to unfamiliar dogs poses little difficulty for pet parents who dislike dog parks and prefer to exercise their dog on isolated hiking trails. In contrast, living with a dog who has recurring ear infections and bites family members when they try to medicate her can be stressful and unpleasant.
Triggers. Are the circumstances that prompt your dog to behave aggressively easy or impossible to avoid? If your dog only guards her food while she’s eating, the solution is straightforward: Keep away from her while she’s eating. If no one can safely enter the kitchen when your dog’s there because she guards her empty food bowl in the cupboard, that’s another story. If your dog bites any stranger within reach, she’s a lot more dangerous than a dog who bites strangers only if they try to kiss her.
Ease of motivating your dog. The final consideration is how easy it is to motivate your dog during retraining. The safest and most effective way to treat an aggression problem is to implement behavior modification under the guidance of a qualified professional. Modifying a dog’s behavior involves rewarding her for good behavior—so you’ll likely be more successful if your dog enjoys praise, treats and toys. Dogs who aren’t particularly motivated by the usual rewards can be especially challenging to work with, and the likelihood of such a dog getting better is small.

"Fixing" Aggression

How to go about working to "fix" aggression issues will depend on the triggers for your pet's aggression. Treatment for a fear aggressive dog will be much different than that for a resource guarder.

You can find a lot of resources on the Internet for understanding and beginning to treat behavior issues. Do take care to ensure any advice you are following is backed up by several other sources, and that the resources you use are positive reinforcement only (no punishments, no shock collars, etc.).

Always Work with Your Veterinarian

Some aggressive dogs behave the way they do because of a medical condition or complication. Therefore, it important to always rule out a physical cause to a dog's aggression before doing anything else. If your veterinarian discovers a problem, you will be able to work together to solve the problem and give your dog her best chance at improving.

In addition to acute painful conditions, dogs can show changes in irritability and aggression due to with orthopedic problems, thyroid abnormality, cognitive dysfunction, seizure disorders, and sensory deficits . Geriatric dogs can suffer confusion and insecurity, which may prompt aggressive behavior.

Always Work with a Professional Behavior Expert

Aggression can be a dangerous behavior problem. It’s complex to diagnose and can be tricky to treat. Many behavior modification techniques have detrimental effects if misapplied. Even highly experienced professionals get bitten from time to time, so living with and treating an aggressive dog is inherently risky. A qualified professional can develop a treatment plan customized to your dog’s temperament and your family’s unique situation, and she can coach you through its implementation. She can monitor your dog’s progress and make modifications to the plan as required. Please see our page of local trainers & resources. Before hiring a trainer, determine whether she has education and experience in treating canine aggression, as this expertise isn’t required for CPDT certification.

If you believe you cannot afford to hire a professional behavior expert, consider researching trainers in your area and what their prices are. With the guidance of a good behaviorist, you do not need to have weekly appointments. Rather, you can get some good ideas to start working with your dog on your own with periodic trainer check-ins.

Can Aggression Be Cured?

Pet parents of aggressive dogs often ask whether they can ever be sure that their dog is “cured.” We can work to reduce and even eliminate the aggressive behavior, but a responsible pet parent will always keep the dog's potential for aggression in the back of her mind to ensure that no one is harmed should a dog's aggressive behaviors be triggered even if it has been years since any such display.

In many cases, the best solution is to try to prevent a dog's exposure to the situations that cause her to become aggressive; for example, if a dog gets aggressive with other canines in the home over her favorite toy, she should only have access to that toy if she is secured in her crate. If they are situations which cannot be avoided, then behavior modification training can help a dog learn to cope and potentially reevaluate the sources of her aggression, for example, if she becomes aggressive with any new stranger, work can be done to help her understand that not all strangers present danger.

Are Some Breeds More Aggressive Than Others?

It’s true that some breeds might be more likely to bite if we look at statistics gathered on biting and aggression. There are many reasons for this. One likely reason is that most dog breeds once served specific functions for humans. Some were highly prized for their guarding and protective tendencies, others for their hunting prowess, others for their fighting skills, and others for their “gameness” and tenacity. Even though pet dogs of these breeds rarely fulfill their original purposes these days, they still carry their ancestors’ DNA, which means that members of a particular breed might be predisposed to certain types of aggression which was historically welcomed. Despite this, it’s neither accurate nor wise to judge a dog by her breed.

A better predictor of aggressive behavior is to view each dog as an individual. What is her temperament? What is his history of interacting with people and other animals?