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The ASPCA calls aggression the most common and most serious behavior problem in dogs, and the number-one reason owners seek help from behaviorists, trainers and veterinarians. If your dog is growling, snapping or lunging more than before, the first step is working out what is behind it. This guide follows the ASPCA’s classification and its advice on when to call a vet or a behavior professional.
If your dog has started showing aggression, book a vet visit before anything else. The ASPCA says a medical check should come before any other step, because pain and illness can cause or worsen aggression.
Rule Out a Medical Cause First
The ASPCA says some aggressive dogs behave that way because of a medical condition. Besides acute painful conditions, it lists orthopedic problems, thyroid abnormality, adrenal dysfunction, cognitive dysfunction, seizure disorders and sensory deficits as causes of changes in irritability and aggression. Older dogs can become confused and insecure, which may prompt aggression. Certain medications can alter mood, and the ASPCA says even diet has been implicated as a possible contributing factor.
If the vet finds a medical problem, the ASPCA says to work closely with the vet to give the dog the best chance of improving.
What Aggression Looks Like
The ASPCA describes aggression as a range of behaviors that usually begins with warnings and can end in an attack. A dog showing aggression to people usually shows some part of this sequence of increasingly intense behavior:
- Becoming very still and rigid
- A guttural bark that sounds threatening
- Lunging forward or charging at the person with no contact
- Mouthing, as though to move or control the person, without significant pressure
- A “muzzle punch,” where the dog punches the person with her nose
- Growl, showing teeth, or a snarl (growling and showing teeth together)
- Snap, then a quick nip that leaves no mark
- A quick bite that tears the skin, a bite hard enough to bruise, or one that causes puncture wounds
- Repeated bites in rapid succession, or a bite and shake
The ASPCA adds that dogs do not always follow this order, and often do several of these at once. Owners often miss the warning signs and think the dog flew off the handle, but the ASPCA says that is rarely the case. It can be milliseconds between a warning and a bite, yet dogs rarely bite without some kind of warning first.
Types of Aggression
The ASPCA says the most useful way to understand why a dog is aggressive is by the purpose of the aggression: what motivates the dog and what she hopes to gain. Its categories, with its own one-line descriptions:
- Territorial. Some dogs will attack and bite an intruder, whether friend or foe.
- Protective. Dogs may act aggressively when they think a family member or friend is in peril.
- Possessive. Many dogs guard their possessions from others, whether they need to or not.
- Fear. A fearful dog may become aggressive if cornered or trapped.
- Defensive. Motivated by fear, these dogs decide the best defense is a good offense.
- Social. A dog who perceives herself as high in status may show aggression toward family members.
- Frustration-elicited. A dog who is excited or aroused by something but held back from approaching it can become aggressive.
- Redirected. A dog is aroused by or displays aggression toward a person or animal, and someone else interferes.
- Pain-elicited. An otherwise gentle, friendly dog can behave aggressively when in pain.
- Sex-related. Intact male dogs still vie for the attention of females in heat, and females compete for access to a male.
- Predatory. Some pet dogs show classic predatory behavior, including chasing and grabbing fast-moving things.
For possessive aggression, the VCA Animal Hospitals describe it as aggression toward humans or other pets that approach a dog holding something highly desirable, such as a chew toy, food or a treat. They note that it is not always food: a stolen tissue, a favorite toy or human food can all be guarded. Our own guide to the territorial type is why dogs mark their territory.
Who the Dog Is Aggressive Toward
The ASPCA says it is essential to know whom the dog is aggressive toward. Its points:
- Aggression toward unfamiliar people is common. The ASPCA cites studies reporting that as many as 60 to 70 percent of pet dogs bark threateningly at strangers and act unfriendly around them.
- Aggression toward family members or other pets in the home is less common.
- Aggression toward children in the family is the most problematic. The ASPCA says it is exceedingly difficult to treat because of safety concerns, and that the likelihood the dog will ever become trustworthy is slim.
- Aggression toward people, toward other dogs and toward other animals are relatively independent patterns. A dog aggressive to other dogs is not necessarily more or less likely to be aggressive to people.
Some dogs are aggressive toward only one category of person, such as the vet, the groomer or the postal carrier. That can sometimes be managed by limiting contact, and sometimes cannot, for example if you live in an apartment building next to a preschool and your dog dislikes children.
Is It Getting Worse?
The ASPCA lists factors that change how risky a dog is to live with:
- Size: large dogs are more frightening and can do more damage than small dogs.
- Age: young dogs with an aggression problem are believed to be more malleable and easier to treat than older ones.
- Bite history: dogs who have already bitten are a known risk.
- Severity: dogs who stop at showing teeth, growling or snapping are significantly safer than dogs who bite.
- Predictability: dogs at the highest risk of being euthanized for aggression give little or no warning before they bite and are inconsistent about it.
- Triggers: whether the circumstances that set the dog off are easy or impossible to avoid.
Our reading: a dog that skips the warning stages and goes straight to a bite is the most urgent case, and so is any aggression toward a child in the home.
What to Do
1. See your veterinarian
The ASPCA says to take the dog to a veterinarian before doing anything else, to rule out medical issues that could cause or worsen the behavior.
2. Work with a qualified professional
The ASPCA says aggression can be a dangerous problem, is complex to diagnose, and can be tricky to treat, and that many behavior modification techniques have detrimental effects if misapplied. It says the safest and most effective treatment is behavior modification under the guidance of a qualified professional, such as a Certified Applied Animal Behaviorist, a veterinary behaviorist or a Certified Professional Dog Trainer. If you pick a trainer, the ASPCA says to check that the person has education and experience treating aggression, because the CPDT certification does not require it.
3. Identify the trigger
The ASPCA suggests asking: who was the target, when and where did it happen, what else was going on, what had just happened or was about to happen, and what seemed to stop it. The answers can show what triggers the reaction. It says you need an accurate diagnosis before you can help the dog.
4. Manage the situation while you get help
For a possessive dog, the VCA say to prevent injury first: confine or supervise the dog so it cannot reach items it guards, and do not give high-value items such as rawhide at all during early training. Teaching puppies early that handling their food and possessions leads to good outcomes can help deter the behavior. The VCA say that if a dog growls, snarls, snaps, lunges or bites over an item, leave the area and do not try to take it; this is dangerous and serious and needs a veterinary behaviorist. Only the adult with the most control over the dog, never a child, should attempt a trade exercise.
The ASPCA’s general point: where a trigger is easy to avoid, avoiding it is part of the solution, and in many cases the only solution is to manage the problem by limiting the dog’s exposure to what triggers it.
Can Aggression Be Cured?
The ASPCA’s answer: the incidence and frequency of some types of aggression can be reduced and sometimes eliminated, but there is no guarantee that an aggressive dog can be completely cured. It tells owners to assume the dog is not cured so they never let their guard down, because even a dog that has behaved for years can meet “the perfect storm” of circumstances. Owners are responsible for the dog’s behavior and must take precautions so no one is harmed.
On breeds, the ASPCA says each dog should be viewed as an individual. It calls individual temperament and history with people and animals far better predictors of behavior than breed, and names socialization and training as the best insurance.
Final Thoughts
Start with a vet visit, then bring in a qualified behavior professional, and manage triggers while you wait. A dog that has been easygoing and changes suddenly is a reason to move faster on the vet visit. If barking at people is part of the picture, see why dogs bark at people; if it is anxiety, see how to calm a dog with anxiety.
Resources
- ASPCA, Aggression
- VCA Animal Hospitals, Possessive aggression in dogs
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