Older Discussion with Q and A

This system for classifying dog aggression is designed to help us understand the most common canine aggression "problems." It is based on scientifically recorded and studied canine behavior, including undomesticated (such as wolves), domesticated (pet population), and stray and feral populations. It also includes the most common terms used by training professionals in the pet- and working-dog fields.

Rationale for Standardizing Terms

There is very little consistency in classifying aggression, particularly in the training community. As a result, many terms are used inconsistently, despite the existence of well-validated scientific studies, particularly in the field of canine ethology. This explains the huge gap between common usage and what is scientifically accurate. Lack of educational and licensing requirements is the main reason for this problem.

This gap has cause confusion among the general public, particularly those seeking help for aggression issues. Too often, aggressive behaviors are labeled as non-aggressive and vice versa. What’s more, systems for classifying aggressive behaviors are inconsistent and frequently contradict well-validated scientific studies. Even worse, very real, potentially serious types of aggression are said to be nonexistent, dominance aggression in particular.

Correctly identifying the aggression type or types that need to be addressed is the necessary first step in developing a plan to manage, rehabilitate, or train an aggressive dog .  If the problem is not correctly diagnosed, plans to solve the problem (or problems) will be hit-or-miss affairs.

Below is a simple classification system based on scientific books and studies, the professional dog-training literature, as well as a qualitative analysis of my own work, spanning over 20 years of working, high volume, mainly with aggressive canines.

What is canine aggression?

Canine aggression is any behavior that, if left uninterrupted, can lead to a dog bite. A behavior such as barking, growling, or even staring can be interpreted as aggression if it is part of a behavioral chain that can lead to a bite.

Targets of canine aggression can be other dogs, humans, other animals, or even objects.

A word about "aggression rehabilitation".

Since many people reading this are concerned about "rehabilitating" a dog's aggressive behavior, we should be clear about what this word means.

“Rehabilitation" is the act of restoring something to its original state. It is derived from the Latin prefix “re-,” meaning “again” and “habitare,” meaning “make fit.”

Aggression is a natural behavior and its presentation primarily depends on a canine's genetics and age. Both these factors determine why and how, if uninterrupted, a dog is likely to be aggressive in certain situations.

Aggressive behavior can be interrupted by various forms of human intervention, particularly training and management, but neither of these is “rehabilitation.”  Both fall under the same category as any other learned behavior and the constraints of maintaining this behavior.

The recent surge in "rehabilitated dogs" being adopted out from rescue organizations and then causing significant injury or death underscores the importance of understanding just what “rehabilitation” means.

For example, if a greyhound has predatory aggression toward cats and a trainer uses an E-collar to shock the dog for trying to chase a cat, that dog has not been rehabilitated. Cat aggression is a natural behavior and the E-collar has been used to stop it. In other words, the dog has not been "rehabilitated,” because chasing cats and other moving animals is a natural behavior.

It’s also worth bearing in mind that unless a trainer knows how to generalize, maintain, and prevent spontaneous recovery of a natural behavior, it’s  likely that, after a while,  the dog will revert to that behavior.

Does rehabilitation occur in dog training plans?

Yes. There are many examples of dogs benefiting from true rehabilitation, but ‘rehabilitation’ must be understood to mean bringing a dog back to, or as closely as possible back to, its natural state.  When a dog has a knee injury, we can try to return the knee back to its original state but, depending on the nature and extent of the damage, that’s often impossible. The same is true of behavioral rehabilitation. In the preceding example, where the greyhound was shocked for chasing a cat, that greyhound may now hesitate to chase an electric rabbit as well as anything else that even vaguely resembles a cat. Rehabilitation is required to return that greyhound as closely as possible to his natural state so that he can participate in races.

It should also be noted that, in some cases, rehab is needed because past experience caused a dog to refrain from behaviors promoting the development of social skills, work behaviors, etc. For example, consider a German Shepherd raised by an owner who bonks the dog over the head with a rolled up towel for behaviors the owner wants to interrupt. If the owner then decides he wants to participate in a dog sport, he is likely to find that he can’t, because whenever the agitator lifts a stick, the dog generalizes, flinches, and loses his grip. That dog is associating the raised stick with past punishment, which makes it harder, possibly impossible, for him to be desensitized to light stick hits on the sport field.

This is when rehabilitation becomes part of the training plan since the dog, in his natural state, did not begin life associating a raised object with punishment and was otherwise more confident with the movement of a human. Will the dog ever completely forget the past? No, but the process of bringing the dog back to a more natural association of lifted objects (neutral) and behavior is rehabilitation.

Sometimes, as a dog matures it becomes more aggressive in certain situations, even if that dog didn’t previously behave "aggressively". If there is no evidence that specific life-events caused the change, it is likely that the progression of aggressive behavior is a product of genetics and maturity. This is why canine ethology at different life stages, as well as breed-specific behavior and bloodline-specific behavior, should always be considered before assuming an alien antagonist to the individual dog's natural behavior.

Understanding the different types of aggression is the necessary first step in developing a plan aimed at ameliorating  problem-causing aggressive behaviors.

A Classification of Aggression Types:

Dominance Aggression

In all animals, dominance is the first right to limited resources. This simple definition makes it easier to identify an aggression “problem” as dominance-related, which is the prerequisite for developing a blueprint to solve it.

Keep in mind that dominance is designed to reduce aggression. The aggression is the result of a conflict. Dominance aggression can and does manifest itself between species if the aggression is triggered over the first right to a limited resource.

In the case of dogs, and other social species the most dominant group members also are the primary leaders. However, although Leadership and dominance are closely related in social animals, but are not the same. It is important to understand the difference for troubleshooting purposes.

A leader is the decision maker for the group. This does not mean that another member of the group may not suggest an activity or otherwise initiate an activity, but ultimately it’s the leader who decides if and when that activity take place.

Among canines this includes travel, hunting, defending from an outsider, accepting an outsider, playtime, as well as other interactions.

Although conflict over leadership can trigger aggression in canines, the term "leadership aggression" is rarely used. This is simply because “leadership aggression” has historically been included in the category "dominance aggression,” since they go hand in hand and -- based on my own experience -- need to be addressed together. That said, in order to develop an effective management and training plan, the trainer must understand how to address these sub-categories individually.

Examples of "Dominance Aggression" (first right to resource):

• first right to human or other dog attention
• first right over food/water
• first right over a toy
• first right to a resting place

Examples of "Leadership Aggression":

• aggression when pack/family tries to leave
• aggression when pack/family member tries to initiate affection
• aggression when pack/family tries to initiate play
• aggression when pack/family tries to interrupt an aggressive behavior
• aggression when pack/family reprimand dog

Resource Guarding

Resource guarding is defensive aggression that is limited to guarding food, water, toys, or other objects that are within the "ownership zone" beneath a canine's mouth and between the front legs.  It should not be confused with "first right" to a resource, because the rules change radically once a dog has possession of a resource.  The following video explains the difference: Dog Culture Made Simple

Although resource guarding is a common occurrence among dogs prone to dominance aggression, it can and often is displayed independently, regardless of social status.

In fact, a study of wolf behavior in the wild by David Mech, has demonstrated that resource guarding is a natural behavior displayed by all wild wolves and is not correlated with social status. A low-ranking puppy is just as likely as an “alpha” to guard food in his “ownership zone.” This type of aggression is not viewed as any form of status challenge and does not typically trigger any kind of retaliation from higher ranking canines.

In short, resource guarding should not be interpreted as a "challenge for status" or as confirmation that a dog believes he has dominant status over a person or another dog.

Some dogs naturally have a stronger instinct for this primitive behavior while other dogs have a less intense instinct due largely to selective breeding.

Understanding what this behavior is and what it is not is the necessary first step toward improving a resource-guarding "problem".

Protective Aggression/Fear Aggression

These two are grouped together because there's just one key difference is relevant to developing a training plan.

Protective aggression is triggered by the instinct of a dog to defend him/herself and other packmates from a threat.

This is a clearly observable behavior in all studies of wild and feral dogs and an instinct that humans have taken advantage of in many working dogs.

"Fear aggression" is a variant of this behavior which is best used as a classifying term instead of protective aggression when the triggers seem to be irrational or inappropriate for a protective response. There may be some gray area as to what constitutes a rational protective response and what would be considered irrational.

A handler’s expectations of her/his dog further complicate the matter. For example, a rottweiler that acts aggressively when a stranger walks within close range on a walk, is more likely to be called "protective" while a Labrador is more likely to be called "fearful" for the same behavior. Therefore, it is somewhat subjective.

Protective Aggression Examples:

• aggression when a stranger hugs the owner
• aggression from a bitch when a stranger handles her puppies
• aggression when a stranger approaches in a "threatening" posture
• aggression toward a dog that approaches with threatening body postures

Fear aggression Examples:

• aggression toward most approaching dogs regardless of the posture
• aggression toward most approaching people regardless of the posture

Fear Biter

The term "fear biter" should not be confused with “fear aggression.” Fear aggression is a preemptive and proactive --"I'm going to get you before you get me or us" -- behavior, while “fear biter” applies to a dog that bites only in defense, and only if flight is not an option.

A typical fear biter may "fear bite" when cornered by a perceived threat, when getting nails clipped, or when he/she cannot escape various other types of fear-eliciting stimuli.

Dogs who are not fear biters, may bite in the identical circumstances. However, whether the bite is the result of protective/fear aggression or dominance aggression, will need to be determined by analyzing their behaviors and body language, preceding the bite. The true fear biter will have fearful body language and will prefer flight if there is an option.

Pain elicited aggression is also grouped here because of the similar motivation to bite which is the avoidance or cessation of pain.

Both dogs will generally prefer no contact over aggression.  The difference is the presence of actual pain in the pain elicited aggression diagnosis vs the perceived anticipation of pain, which may be irrational and based on a phobia, in the fear biter.

A similar comparison can be made of dogs labeled as protective aggressive vs fear aggressive.  The difference mainly lies in the rationale of the aggression.

Territorial Aggression

Territorial aggression will have a very similar presentation as protective aggression and can, in fact, be very intense.

True territorial aggression is motivated by the instinct to protect a perceived territory from outsiders. Perceived territory can range from the inside of a house, to a yard, or even to the entire neighborhood in which a dog is regularly walked.

A key indicator of territorial aggression is that a dog is very aggressive toward an outsider (dog or human) when that outsider enters his territory but is not aggressive when strangers are encountered in a new or neutral area.

Since territorial aggression will have a similar presentation as protective or fear aggression, it can be masked by fear aggression if the dog is also acting in a similar manner off property due to fear. Therefore, a dog that displays aggression on and off property to those that seem to pose little threat may or may not also have a layer of territorial aggression.

Territorial aggression is never directed toward other pack members. Therefore, dogs that protect resting places, crates, food, or rooms in the home from other family members should not be labeled "territorial". Instead, those behaviors need to be correctly identified as dominance or resource guarding. Technically, if a dog was exhibiting territorial aggressive toward a family member, the dog would attack the family member as soon as the member entered the yard/home.

It's important to bear in mind that different forms of aggression are motivated by different reasons and therefore must be treated differently to manage any problems successfully.

Wild canines are fiercely territorial, which is why the biggest natural killer of wolves is territorial conflict with other wolves. Humans have taken advantage of this instinct during the domestication of guardian breeds. If a wolf is behaving aggressively toward pack mates within pack territory, it is not territorial aggression. This applies equally to domestic dogs.

Another behavior that’s sometimes confused with territorial aggression is Alert Barking.

Alert Barking

Alerting barking is simply the enhancement of the muffled "woof" sound wild canines make to warn pack mates of intruders. Technically, this is not aggressive behavior since, at the core, the bark's purpose is to warn pack members, not threaten others.

Predatory Aggression

Most aggressive behavior is motivated by a threat or challenge of some kind to territory, resources, status, self, or pack.

Predatory aggression, on the other hand, is related to the instinct to hunt, chase, kill, dissect, and eat.

The wildtype predatory motor sequence consists of : orient > eye > stalk > chase > grab-bite > kill-bite > dissect> consume.

This instinct has been highly manipulated through domestication to help various breeds perform specialized tasks. By using controlled breeding to suppress or enhance particular elements of the predatory sequence, humans have created dogs that show the micro-divisions of this instinct in different combinations (see a video explaining this here). For example, a border collie has strong instincts to stalk and chase, but a lower instinct to bite. This is what enables the border collie to perform the task of herding sheep without injuring them.

If a dog's predatory instinct shows signs of escalating to an unwanted, damaging bite, the dog is considered to be displaying predatory aggression.

Play Aggression

As with other social predators, puppy and dog play is mock/practice predatory and fight behavior whose main purpose is to prepare the dog for adulthood.

In contrast to the mature forms of aggression, play “aggression” is characterized by more relaxed body and face postures, and by relatively restrained bites.

Play aggression can be used to teach young working dogs specific techniques that are subsequently refined and developed during more realistic training scenarios.

Play aggression can still be a nuisance and cause injury to pet owners and their children if it’s not channeled and managed properly.

That said, play aggression should not be confused with its mature forms and needs to be handled differently.

Barrier Frustration

This is aggression that manifests itself due to the frustration of not being able to engage with something when restrained by a leash or blocked by a barrier.

If this is the sole reason for the aggressive behavior, it will subside when the restraint or barrier is removed.

Barrier frustration can also be layered on top of and exacerbate other types of aggression, such as predatory, fear, dominance, or territorial. If this is the case, the dog will remain aggressive even after the leash-restraint or the barrier has been removed.

Barrier frustration, layered on top of another type of aggression, can lead to misdirected aggression, which describes what happens when a dog bites a substitute for the intended target.

As with all types of aggression, barrier frustration has a strong genetic component. In most cases, it has been selectively bred into dogs for a purpose.

A classic example of barrier frustration can be observed in lines bred for sport work, where the breeder chooses his stock based on ease of training the offspring to bark when restrained.  This is useful during the bark- and-hold training exercise in IPO. The frustration will look more aggressive and impressive to a judge, who is otherwise looking at a dog primarily engaged in play aggression under the layer of frustration.

If a puppy from this stock is purchased as a family pet, the owner will almost inevitably have problems because the dog will behave aggressively when restrained from meeting other dogs. This can be a turbo boost layered over other types of aggression when the dog is on-leash or otherwise restrained.

Skipping Steps in the Aggression Cycle

Ideally, a dog shows a lot of restraint when acting defensively. In many situations, the dog may accomplish what is needed by a posture and if the other dog or human doesn’t back off, escalate to a growl, snarl, snap at the air, a "hit" in which the dog hits a competitor with his teeth without breaking skin, and then escalating bite-levels intended to cause more serious injury, before moving to an all-out fight or attack.

We can typically observe appropriate restraint and the use of the least amount of aggression required to resolve a conflict during resource-guarding and normal dominance-related conflicts.  When this kind of step-by-step escalation of aggression does not occur, we say that the dog is "skipping steps in the aggression cycle".

Skipping steps in the aggression cycle can, in rare cases, have been caused by someone punishing the dog for early steps in the cycle, particularly growling.

Usually, genetics is the main culprit and the behavior can be found in bloodlines of many breeds that are otherwise not known for overly aggressive behavior but were haphazardly bred.

In other bloodlines, the behavior was an intentionally selected for trait that gave an advantage to certain working dogs, terriers, and fighting breeds that needed the advantage of a quick bite to excel at their tasks. Skipping steps in the aggression cycle can also be associated with not responding to signals of surrender and submission after the onset of aggression.

One type of aggression can be layered over and exacerbate other types of aggression.

Dogs are multidimensional, and usually show most forms of aggression to one degree or another. This is why we must be very careful before concluding that a dog has just one kind of "aggression problem.” Generally, most problems are caused by more than one aggression type.

We need to respect the fact that aggression is natural to a dog and what’s a problem in one situation is an asset in another.

Aggression problems are only problems when they cause a problem.

Understanding these "problems" instead of trying to suppress natural behavior should always be the first step in any plan.

Hacks and "quick fix it" plans will always yield bad side effects.