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.
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
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
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 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 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-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 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
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.
Animals may exhibit aggression in response to pain, even in the absence of
any signs of fear, withdrawal, avoidance, or anxiety.
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.
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.):
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.
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.
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
Rage Syndrome: This condition is characterized by
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
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.
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.
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.
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.
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
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.
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