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Description or definition:

All dogs are capable of aggressive behavior.  There is no single definitive “cause” of aggressive behavior in dogs.  Development of aggressive behavior depends on a variety of things including both genetics and environment.  For example, a dog that is genetically predisposed to certain types of aggression, but discouraged at an early age from displaying the behaviors, may not ever exhibit the behaviors.  On the other hand, a dog who is not genetically predisposed to aggression, but who is encouraged (intentionally, or unintentionally) to exhibit certain types of behavior can learn to display aggressive behavior.  Additionally, pain or medical conditions can cause aggressive outbursts in a dog that has an otherwise gentle and placid nature.


Aggressive behavior in canines is often separated into the following categories.


Dominance Aggression: Since dominance aggression is the number one problem treated by behaviorists, this summary will focus more on this type of aggression than some of the others.  Dominant aggression is aggressive behavior that is used to control people or other dogs.  Dominant aggression is thought to develop in two types of dogs.  Those that are confident and feel that they are in control and can cause others to do their bidding.  And those that are unsure of their social status and use this type of behavior to discover what is expected of them.  

 Some typical signs of early dominant behavior can include a dog standing on its owners feet, leaning against them, “talking back,” standing in front or the doorway, blocking the owner, or attempting to knock them over, demanding affection and/or jumping in your lap, placing a paw on the shoulder of another dog during introduction and/or play and/or mounting another dog during play, excessive territorial marking.  When introduced to another dog of social maturity, dominant dogs may stand tall, with their ears up and forward, tail high and wagging slowly and stiffly from side to side, with raised hackles, staring, and/or growling lowly with lips pursed and teeth exposed.  If the other dog displays submissive behavior, these displays subside.  Dogs that display aggression toward other dogs regardless of social maturity, or submissive reaction in response to the display, are considered dog-aggressive not dominance aggressive.

A dog can be confident, even pushy and assertive without being aggressive.  A dog can “talk back” and snort at you, or demand affection, without being aggressive.  However, the longer controlling behaviors are tolerated, the more the behavior is likely to escalate into aggression as the dog begins to enter into social maturity (18-36 months).  Once a dog has begun growling or snarling when a person reaches over its shoulders or head, handles its muzzle or face, looks it in the eye, reprimands it, or disturbs it while sleeping, the pushy behavior has risen to a level that is now considered aggressive. 

Intact males are more likely to exhibit dominance aggression than neutered males or females.  It is speculated that there may be a link to dominance aggression and the hormone androgen since female dogs who show aggression before puberty and who are spayed often become more dominant.  Because dominance aggression is about control (the dog thinking the dog is in charge), leash correction and physical punishment often can make dominance aggression worse.  Dogs that are dominant aggressive do not necessarily display food aggression, possession aggression, or territorial aggression, however these aggressions can be correlates of dominance aggression and, when associated with it, may be indicative of a more severe situation.


Territorial Aggression: Territorial aggression is aggression that is consistently displayed within or near a specific area (like a car, or yard) when that area is approached by another individual regardless of whether there is a threat from that individual.   It is often characterized by barking and lunging.  Most dogs, if allowed to, will exhibit some varying degree territorial aggression (barking at the door, barking at the mailman, patrolling the yard or house perimeter).  And in many pet dogs the behavior, in a moderate degree, is seen as desirable and even encouraged by their owners.  However, this behavior can escalate, particularly if the dog is allowed to “patrol” and protect an area separated by a barrier (such as a fence, window, door, or even inside of a car).  One characteristic of a territorial aggressive dog, is that the dog will often not show any aggressive behavior at all when taken into an unfamiliar context (no “property” to protect).  Some people feel that protective aggression and territorial aggression are the same, or at least related.  Others divide them into separate categories.


Protective Aggression: Protective aggression is aggression that is consistently displayed when a third party approaches an individual or class of individuals (usually the owner, another dog, or other animal in the dog’s “family”) that the dog sees as a member of his or her pack.  Many pet dogs will exhibit some varying degree of protective behavior.  And in many pet dogs the behavior, in a moderate degree, is seen as desirable and even encouraged.  The behavior can, however, escalate to an unacceptable level.  Some dogs with a protective nature can become agitated into acting aggressively if the owner grabs the dog by the collar, or tightens up on the leash when greeting a third party.  One characteristic of protective aggression is that the dog will frequently fail to display the behavior in the absence of its owners (no owner to protect).  There is some thought that protective and territorial aggression are the same, or at least related.  However, others prefer to divide these types of aggressive behavior into distinct categories.

Fear or Defense Aggression:  Fear or defense aggression is aggression is most often displayed when a dog with a timid-nature is placed in a situation that it finds overwhelming and has no ability to withdraw from the situation or avoid confrontation.  Fearful dogs often display submissive body language (ears back, flat against the head, avoidance of direct eye contact, lowering of the head and body, tucking tail between the legs).  They do not handle stress well and may lick nervously, roll over to expose their belly, and submissively urinate.  Often these dogs resist handling and will shy away from people.  If forced into a corner, or into a situation where they are overwhelmed and cannot withdraw, they may snap and growl or even bite as the person turns to walk away. 

Food Aggression: Food aggressive dogs consistently display aggression in the presence, and only in the presence, of pet food, bones, rawhides, biscuits, blood, or human food in the absence of starvation, or neglect.  Food-related aggression is a separate type of aggression unrelated to possession or dominance aggression.  However, the behavior may also occur in conjunction with other forms of aggression including possession and/or dominance aggression.  Dominant dogs may try to control another dog’s activities, including access to food as a display of hierarchy.   However, food aggressive dogs consistently display aggressive behavior whenever food is present.  For example, they will often guard their food and/or growl even in the absence of any threat to the food or presence of another dog.


Possession Aggression: Possession-related aggression is aggressive behavior that is consistently directed toward another individual (human or animal) whenever that individual approaches or attempts to obtain a non-food object or toy  to which the aggressor has regular access.  For example, it need not be necessary that the dog has the item at that particular moment, it may become aggressive merely upon seeing another individual with the object.  A dog can have possession aggression without having other forms of aggression such as food or dominance aggression.  Or, the behavior can occur in conjunction with other forms of aggression.  Dominant dogs may occasionally try to control another dog’s access to an object as a display of hierarchy, however, possession-aggressive dogs consistently display aggressive behavior whenever they have access to a toy or other object that they consider a “possession."


Maternal Aggression: Maternal aggression consists of unprovoked, age-inappropriate attacks on puppies by their mother.  The behavior is usually obvious, even if the puppies are not injured or killed, as the mother will display consistent aggressive behavior directed toward the puppies in the absence of pain, challenges, or threats.


Predatory Aggression: This involves behavior that is consistent with predatory behavior such as staring, lowering the head and body, salivating, stalking, and ending in a bite and shaking motion of the head.  Predatory aggression is more normally associated with specific species that are seen as prey (birds, cats, small animals).  However, it can also be triggered by uncoordinated movement  (injured animals or people, infants, small children, the elderly) or fast movement (joggers, skate boarders, bicyclists).  Some degree of predatory behavior is normal in all predatory animals, including canines.  However, the behavior can escalate to an unacceptable level in some animals.


Redirected Aggression: This is aggressive behavior that usually occurs in conjunction with some other form of aggressive behavior.  A dog has re-directed aggressive tendencies if it consistently directs aggressive behavior at a third party whenever it is interrupted from exhibiting aggressive behaviors toward another target.  This should be distinguished from a situation where the aggression toward the third party was accidental.  For example, the sort of situation where a person reaches between two fighting animals to break up the fight and is bitten because the dog was either in the process of biting the other and could not stop in time, or did not see the person’s hand.

Dog-Dog Aggression or Inter-Dog Aggression: Dog to Dog aggression is often confused with dominance aggression.  A dominant dog will often attempt to establishing himself as leader and will display aggressive behavior toward other dogs of similar age and social status.  However, a dominant aggressive dog is not generally aggressive toward other dogs that are submissive, or under the age of social maturity.  On the other hand, a truly dog-aggressive dog, will display consistent aggression toward any dog regardless of context, social hierarchy, social maturity, sex, presence of threat, or submissive response received by the dog it is displaying the aggressive behavior towards.  Dog aggressive dogs are not necessarily aggressive towards humans or other animals.


Frustration Aggression:  Researchers studying aggression in dogs noticed that dogs who were not allowed to interact “naturally” with other people and other dogs were more prone to displays of aggressive behavior.  This behavior has been termed “frustration aggression.”  The longer a dog is physically restricted from normal interactions (interactions with people, other dogs, and the outside world), the dog develops a more and more intense desire to gain access to those things.  This increasing excitability can grow from mere exuberance to overwhelming agitation, frustration, and aggression.  As a result, dogs who are regularly tied, regularly confined to an apartment or yard with windows or a chain link fence, regularly walked on a tight leash, or otherwise regularly confined in a situation where they can observe other people and dogs but have no ability to interact with them on a normal level have a significantly higher number of incidents involving unprovoked aggression.


Play Aggression: Out of context, consistent aggression in response to play or in context in which play behaviors (play-bows, yips, shoulder blocks, etc) would normally occur.  This should be distinguished from normal rough play or attention seeking behavior, both of which are learned in interactions from other animals or people.


Pain Aggression:  Animals may exhibit aggression in response to pain, even in the absence of any signs of fear, withdrawal, avoidance, or anxiety.


Learned Aggression: Dogs can be intentionally trained to act aggressively on command (or in particular situations).  However,  learning is also an important component of most other types of aggression.  Whenever a dog learns that aggression is successful at removing a stimulus, or gaining a reward, the aggressive behavior is further reinforced.  Many of the above categories of aggressive behavior can be learned responses. 

Potential Medical Causes of Aggression:

There is speculation that there are some 50 potential medical causes for aggression in dogs.  Some of the more commonly noted ones are listed below (NOTE: This information has been provided for educational purposes, these medical causes have NOT been seen in Shilohs.):


Thyroid-Dysfunction:  Hypothyroidism is the most prevalent endocrine disease in dogs.  The hypothyroid dog is generally thought of as being lethargic and mentally dull, however, aggression and hyperactivity are also common responses to a low thyroid level.  Thyroid dysfunction as a potential cause of aggressive may go undiagnosed because the behavioral signs often precede the more traditional skin, coat and metabolic changes characteristic of hypothyroidism.  This condition can be detected through a blood test and treated through synthetic hormones.


Brain Chemistry:  Serotonin is thought to play an important role in the neurochemical control of aggression in the brain.  The family of SSRI drugs may be helpful in treating aggression related to brain chemistry.


Epilepsy: Seizures occurring in a region of the brain that controls aggression can cause sudden unprovoked aggression.  Depending on the location of the area of the brain that is affected, a dog having a complex partial seizure may exhibit behavioral, but not physical, signs of the seizure, including aggression.  These types of seizures cause distortions of thought, perception, “emotion” (an increase in fear, or aggression), and visual and auditory hallucinations.  Physical signs in addition to aggression could include one or more of the following: sudden lip-smacking, chewing, “fly biting,” vocalization, hysterical running, cowering, vomiting, diarrhea, abdominal distress, excessive salivation, blindness, unusual thirst or appetite, and flank biting.  Dogs that experience visible physical convulsions, are often more aggressive immediately following the seizure.  Dogs in either state are not fully aware of what they are doing.  Epilepsy is treatable with medication, but diagnosis is sometimes difficult in dogs that are experiencing complex partial seizures.


Canine Rage Syndrome: This condition is characterized by sudden episodes of aggression, often directed at the dog’s owner (or other people most often around the dog).  Many owners report that the episodes are completely unpredictable.  Others report that the episodes are triggered by specific stimulus that varies depending on the dog.  The episodes are characterized by extreme aggressiveness, often including multiple bites or bite attempts, and the episodes stop as suddenly as the begin.  Dilation of the dog’s eyes are often reported prior to the attack.  And the dog is often said to seem confused or “remorseful” about what he has done following the attack.  There is a lot of speculation about  the cause of this syndrome.  The two most common theories is that it is either a form of seizure, or that these dogs have an underlying chemical imbalance (such as reduced serotonin levels)  that are associated with similar violent outbursts in people. Many people prefer to refer to canine rage syndrome as idiopathic aggression because the condition is not really related to human emotions such as “rage” or “anger.”  However, the term idiopathic aggression more properly refers to sudden unpredictable outbursts in which no underlying  neurological or other medical condition is present.  Canine Rage Syndrome is sometimes also referred to as Behavioral Seizure disorder.


Hypoglycemia/Diabetes: Dogs, like humans, can be either diabetic or hypoglycemic.  Both diabetic and hypoglycemic dogs can go into a state of very low blood sugar.  Symptoms include moodiness, irritability, aggression, staggering or collapse, weakness, and staring with a glassy-dazed look.  Hypoglycemia and diabetes are easily detected through a blood test. 


Cognitive Dysfunction Syndrome: degenerative changes in the brain, resulting in brain cell loss can cause aggression in dogs.  This condition is typically associated with advanced age.  In addition to irritability and aggressive behavior some of the other symptoms may include sudden unexplainable anxiety and/or disorientation, aimless wandering,  inappropriate elimination (“accidents” in housetrained dogs), social detachment, changes in activity level, and changes in sleep-wake patterns.


Brain Tumors:  A brain tumor can cause changes in temperament including aggression, confusion, irritability, increased vocalization, apathy, hyper excitability, tremors, weakness, disorientation, visual deficits, circling, falling, sleep habits, abnormal postures, exaggerated gait, head tilt, pain, house soiling, staring, trembling, decreased appetite, seizures, paralysis.


Encephalitis: Both bacterial and viral encephalitis (distemper) are known to cause aggression in dogs.  But any condition that causes inflammation of the brain can cause neurological signs, including aggression. 


Head Trauma: When the brain has suffered an injury, swelling or bleeding may result.  This can in turn interfere with the normal function of that part of the brain causing unusual neurological symptoms, including aggression.


Diagnosis and Treatment:

Problems with diagnosing a dog as “aggressive” arise from human misunderstanding of canine social systems, canine signaling, and canine anxieties about contextually appropriate responses to unfamiliar situations.  A diagnosis of an “aggressive temperament” should not be based on a one-time event.  Often the dog has been displaying signs of an upcoming problem  (unbeknownst to the owner) and has been allowed to continue the behavior until it has escalated to a full scale problem.  Diagnosis of aggression, and the cause of the aggression, requires an evaluation (by qualified medical and behavioral specialists) of the type of behavior that the dog is displaying, the dog’s medical condition, its background (if known), and its present environment.  Treatment for aggressive behavior can include medication,  but most often includes behavior modification in conjunction with an experienced behaviorist or trainer.  Rehabilitating a truly aggressive dog is not an easy fix.  Aggressive behavior does not develop overnight, and cannot be “cured” overnight – or by sending the dog away to a training camp.  Management of an aggressive dog requires constant commitment, consistency, and follow through from the owner of the dog, for the life of the animal.


If your dog is exhibiting aggressive behavior seek the medical advice of a licensed veterinarian, and training advice from a professional animal behaviorist knowledgeable about your breed of dog and the specific type of behaviors that you are concerned about.  Many licensed veterinarians keep a list of recommended behaviorists in your area.


Links to sites about this condition:



This summary provided by: 

bulletJessica Schepler
bulletWildfire Kennel



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Copyright © 1998 - 2009. Shiloh Shepherd Dog™ Club of America.
All rights reserved. Revised: January 2008

The information on this website was written by ISSR breeders and other concerned individuals, however we are are NOT veterinarians. This information is being provided as a general overview, from information we were able to find about each disease through our own research. These summaries are not intended to be relied upon as medical or veterinary advice, nor do we consider ourselves experts in the veterinary field or in any of these conditions. While we do our best to provide the most up to date information, new research is constantly being done on these diseases. We recommend that you do further study and talk to your veterinarian on any topics you see here, as we cannot guarantee that the information posted here is the most current information available.  This site was originally designed and maintained by Debbie Knatz.