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CANINE AGGRESSION – OVERVIEW OF
DIAGNOSIS AND TREATMENT
Aggression is the most serious and dangerous behavior
problem that dog owners may need to face. Since there are
many different types of aggression, making a diagnosis,
determining the prognosis (the chances of safe and effective
correction) and developing an appropriate treatment plan are
usually best handled with a veterinary or applied animal
behaviorist. In some cases medical conditions can contribute
to aggression, therefore before a behavior consultation it
is essential that your dog have a complete physical
examination and a set of blood tests to rule out organ
dysfunction (See our handout ‘Behavior – causes and
diagnosis of problems’). In order to treat the problem
effectively, it will first be necessary to determine which
type of aggression your dog displays:
dominance/conflict-related, fear, possessive, protective and
territorial, parental, play, redirected, pain induced,
pathophysiological (or medical) or learned. In many cases
more than one form of aggression may be exhibited (See our
handout on ‘Aggression – introduction to aggressive
behavior’).
Why might a dog become aggressive to its owners? Could this
be dominance aggression?
One of the most common types of aggression seen by
veterinary behaviorists is related to the relationship
between the dog and family members and is often called
dominance/conflict-related aggression. In order to achieve
security and cohesiveness within a group or pack, a
hierarchy develops amongst groups of dogs. Social control in
the group is maintained through dominance displays, threats
and deferential responses between the individual pack
members. This type of communication helps to maintain group
harmony with a minimum of fights and injuries amongst pack
members. Although it is not clear if the concept of
hierarchy applies to dog - human relationships, your dog is
programmed (and limited) through genetics and learning to
act like a dog (e.g. to communicate with canine postures,
body language and actions) in its interactions with people,
other dogs, and other animals.
In the home, your dog may display actions and postures that
range from those indicating control and leadership to
deference and compliance in relationship to each family
member. Dog / owner relationships develop from a combination
of genetic factors and learning, i.e. the day-to-day
interactions with each family member. Most interactions with
family members are likely to be aggression free, but when
there are conflicts, aggressive displays may arise. Most
aggression towards family members arises out of fear or
anxiety, as a defensive response (e.g. to punishment), when
in possession of a favored resource, or in play. There also
appear to be cases, especially in more assertive dogs, where
the dog uses threats or even aggression to avoid being
petted, hugged, handled or moved especially when resting or
sleeping and this might be referred to as dominance
aggression.
The owners response to an aggressive display shapes the dogs
behavior for future interactions and this may differ from
situation to situation and from family member to family
member. Owner’s that retreat or give in to their dog’s
aggressive demands are inadvertently reinforcing their dog’s
behavior (although this may be prudent when the dog is
threatening harm). Owners that respond with fear, punishment
or retaliation will increase the pet’s fearfulness and
aggressiveness especially during similar situations in the
future. Owners that respond unpredictably will cause the pet
to be in conflict as to what response might be expected in
the future. Therefore, much of what has been commonly known
in the past as dominance related aggression may in fact be
comprised of possessiveness, fearful and defensive
responses, learned behavior, conflict induced behavior, or
an owner impinging on the pet’s personal space or critical
distance when the pet is not interested or prepared for
social interactions. In cases where the aggression is out of
context with the threat or challenge or lacks normal
inhibition, there may be an impulse control disorder
underlying the aggression.
Once a dog develops a position where it can control
resources and social interactions, any challenge to that
dog’s control may lead to aggression. Dogs that learn to
achieve their goals with aggression are reinforced for their
actions if the stimulus retreats. On the other hand, owner
responses that are confrontational or disciplinary can lead
to more intense retaliation and aggression, particularly
from dogs that are fearful and defensive.
Dogs use facial expressions and body postures as signals to
display assertive behavior, such as standing tall, a high
wagging tail, eye contact, or snarling. However, in cases
that are referred to as dominance aggression, it’s also
possible that the dog might have appeared defensive and/or
fearful in early encounters and has learned that aggressive
displays achieve a goal (removing the threat). When there
are competing motivations (approach / withdrawal, social /
fearful) this state of conflict may then lead to aggression.
Aggression towards family members in one or more of the
following circumstances along with assertive signaling may
indicate dominance or conflict related aggression with
either genetic or learned components or both:
• Protecting resting areas or resources (food, toys)
• Overprotection of a more subordinate family member
• Staring, eye contact
• Handling by the owner (lifting, petting, hugging, rolling
over onto back or side)
• Restraint, pulling, pushing, discipline, punishment
The presence of these signs alone is not diagnostic of
dominance aggression as they can also be seen with other
forms of aggression. If any of these signs are displayed
along with fearful, anxious or mixed signaling then a
diagnosis of conflict or fear elicited aggression is more
likely. (For treatment, see handout on ‘Aggression toward
family members‘).
What is fear aggression and how is it diagnosed?
Fear aggression arises when a dog is exposed to people or
other animals that the dog is unfamiliar with or to those
that have been previously associated with an unpleasant or
fearful experience. Although some dogs may retreat when
fearful, those that are on their own territory and those
that are prevented from retreating because they are cornered
or restrained, are more likely to fight. If the person or
animal retreats, acts overly fearful or the pet is harmed or
further frightened in any way (e.g. a fight, punishment),
the fear is likely to be further aggravated. Fear aggression
toward family members might arise out of punishment or some
other unpleasant experience associated with the owners. Many
cases of fear aggression are seen as combinations or
complicating factors of other forms of aggression
(dominance/conflict, maternal, possessive, etc.). Fearful
body postures in conjunction with aggressive displays are
diagnostic of fear aggression; however, in some cases, as
dog learn that aggression changes the outcome of the
encounter, their body postures may become more confident but
the underlying motivation of fear is unaltered. Behavior
therapy, perhaps in combination with drug therapy can be
used to treat most cases of fear aggression. (See handout on
‘Fears and Phobias – animals and people’).
What is play related aggression and how is it diagnosed?
Play-related aggression is commonly seen in young dogs
toward people or other pets in the family. Overly
rambunctious play, along with grabbing, nipping or biting of
people or their clothing are some of the common signs of
play-related aggression. Although it is a normal behavior,
it can lead to injuries and, if handled incorrectly could
lead to more serious forms of aggression as your dog
matures. (See also our handouts: ‘Canine Aggression –
sibling rivalry’; ‘Puppy Biting’, and ‘Play and exercise in
dogs’).
What is possessive aggression and how is it diagnosed?
Possessive aggression may be directed to humans or other
pets that approach the dog when it is in possession of
something that is highly desirable such as a favorite chew
toy, food, or treat. While protecting possessions may be
necessary if an animal is to survive and thrive in the wild,
it is unacceptable when directed toward people or other pets
in a household. What can be confusing for some owners is
that it is not always food that brings out the most
protective displays. Novel and highly desirable objects such
as a tissue that has been stolen from a garbage can, a
favored toy, human food, or a piece of rawhide are some of
the items that dogs may aggressively protect. Possessive
aggression should be considered whenever the dog does not
willingly relinquish possessions and uses aggressive
displays and responses to keep them. The dog’s motivation
and ability to hold on to the object (which might include
aggression) might also be referred to as its resource
holding potential (See our handout on ‘Possessive
aggression, toy and food guarding’)
What is protective or territorial aggression and how can it
be diagnosed?
Protective aggression may be exhibited toward people or
other animals that approach the pet’s property (territorial
aggression). Generally people and other animals that are
least familiar to the dog, or most unlike the members of the
household are the most likely “targets” of territorial
aggression. While most forms of territorial aggression are
likely to occur on the property, some dogs may protect
family members regardless of the location. Territorial
aggression can be prevented or minimized with early
socialization and good control. Young dogs should be taught
to sit and receive a reward as each new person comes to the
door. To reduce potential fear and anxiety toward visitors,
you should ensure that a wide variety of visitors come over
to visit the puppy, while the puppy is young and sociable
(See our handout on ‘Socializing your new puppy’). In time,
most dogs will begin to alert the family by barking when
strangers come to the home. However the dog that has been
well socialized and under good control can be trained to
quickly settle down and relax. Territorial aggression can be
a learned form of aggression. For example when a puppy first
beings to bark at novel noises and visitors that arrive at
the property (alerting, alarm barking), the dog’s genetics,
socialization and previous experience along with the
consequences of the event (outcome) will begin to shape
further responses. Owners that are angry, frustrated or that
yell at or punish the dog, may lead to a fearful association
(pairing/conditioning) with the stimulus (arrival of
visitors, knock at the door, doorbell). Similarly if the
stimulus is particularly unusual (e.g. wearing uniforms,
carrying mail bags) or threatens the dog in any way (shoving
items inside your door, threatening the dog, spraying pepper
spray) this may further enhance the dog’s fear of visitors.
In addition, should the dog bark or growl and the stimulus
retreat, the behavior will have been reinforced. Therefore
learning may be a major contributing factor to territorial
aggression. For treatment of dogs with territorial
aggression see our handout on ‘Canine Territorial
Aggression’.
What is predatory behavior and how can it be diagnosed?
Predation is the instinctive desire to chase and hunt prey.
Predatory behaviors include stalking, chasing, attacking,
and ingestion of prey animals, but may occasionally be
directed at people or other pets. Some dogs that have never
shown chase or predation, may display the behavior when
running together with a group of dogs. Although the desire
to chase can be reduced by using a head collar and
desensitizing and counter-conditioning in the presence of
passing stimuli, this is a very dangerous form of
aggression, which must be prevented. Whenever the dog is
outdoors it should be confined to an escape-proof pen or
run, or controlled securely by the owners. A leash and head
collar or a leash and muzzle can help to ensure safety when
out for walks. (Also see handouts on ‘Behavior
modification’, ‘Controlling chase’, ‘Controlling pulling and
controlled walk’).
What is pain-induced and irritable aggression and how can it
be diagnosed and treated?
Some form of handling or contact that causes pain or
discomfort usually elicits pain-induced aggression. However,
even if your dog is not exhibiting pain, certain medical
conditions (endocrine imbalances, organ disease, etc.) may
make the pet more irritable and perhaps more prone to
aggression. Fear and anxiety further compound many of these
cases. Once your dog learns that aggression is successful at
removing the stimulus, aggression may recur when similar
situations arise in the future, whether or not the pain is
still present. Treatment requires that the medical or
painful condition is resolved first. Next, you will need to
identify the types of handling and situations that have led
to aggression in the past. With desensitization and
counter-conditioning, your dog can slowly and gradually be
accustomed to accept and enjoy these situations. Once the
dog learns that there is no more discomfort associated with
the handling, but that there may be rewards, the problem
should be resolved. A muzzle or leash and head collar, may
be the safest way to begin the retraining. (See our handout
on ‘Behavior Modification – Counter-conditioning and
Desensitization’)
What is maternal aggression and how can it be diagnosed and
treated?
Maternal aggression is directed toward people or other
animals that approach the bitch with her puppies. When
bitches go through pseudopregnancy (false pregnancy) they
may also become aggressive and begin to protect nesting
areas or stuffed toys at the approximate time when the
puppies would have been born. Once the litter of puppies are
weaned and the dog is spayed the problem is unlikely to
recur. In the interim, the owners can use a leash or leash
and head collar, along with the ‘come’ command and rewards
to teach the dog to leave the litter, at which time the
puppies can then be handled. With desensitization,
counter-conditioning, good control and highly motivating
rewards, it may be possible to train your dog to accept
approach and handling of the puppies.
What is redirected aggression and how can it be diagnosed
and treated?
Aggression that is directed toward a person or pet that did
not initially evoke the aggression is classified as
redirected aggression. This is likely to occur when the dog
is aroused and a person or other pet intervenes or
approaches. Dogs that are highly aroused must be avoided. In
some cases a water rifle, air horn, or long leash can be
used to safely remove the dog from the situation. If the
aggression and arousal does not immediately subside,
consider locking your dog in a dark, quiet room until it
settles down. Since redirected aggression arises out of
other forms of aggression, it is important to identify and
treat or prevent the initial cause of aggression (e.g. fear,
territorial, sibling rivalry, etc.). This can be
accomplished by avoiding exposure to the stimulus for
aggression or by keeping a leash and head collar or leash
and muzzle on your dog when exposure is possible. (Also see
our handout on ‘Redirected Aggression in Cats’)
What is learned aggression and how can it be diagnosed and
treated?
Although learned aggression can refer to dogs that are
intentionally trained to act aggressively on command (or in
particular situations), learning and conditioning are also
important components of many forms of aggression. Whenever a
dog learns that aggression is successful at removing the
stimulus, the behavior is further reinforced. Owners who, in
an attempt to calm the pet and reduce aggression, actually
encourage the behavior with petting or verbal reassurances
will inadvertently reward some forms of aggression. Pets
that are threatened or punished for aggressive displays may
become even more aggressive each time the situation recurs
because they have come to associate the stimulus with an
adverse outcome; the punishment. In addition, if the
response of the owner, or the stimulus (person or other pet)
is one that evokes anxiety or fear, the aggression is likely
to escalate. When learned aggression is present, the
underlying stimuli must be identified and a treatment
program designed to teach the dog new responses. (See
handout on ‘Behavior Modification, desensitization,
counter-conditioning’).
What are some of the other causes of aggression?
Aggression associated with medical disorders may arise at
any age, may have a relatively sudden onset and may not fit
any canine species-typical behavior. Some medical conditions
can, on their own, cause aggression, but in many cases a
combination of behavioral factors and medical problems cause
the pet to pass a certain threshold at which aggression is
displayed. Infectious agents such as rabies, hormonal
imbalances such as hypothyroidism, psychomotor epilepsy,
hyperkinesis, neoplasia, and a variety of genetic and
metabolic disorders can cause or predispose a dog to
aggression. Painful conditions such as dental disease or
arthritis, and medical conditions causing fever, fatigue or
sensory loss might increase the pet’s irritability (See our
handouts on ‘Behavior – causes and diagnosis of problems’
and ‘Behavior problems of older pets’).
In rare circumstances, aggression has no identifiable
etiology and no particular stimuli that initiate the
aggressive displays. There may be a genetic propensity to
aggression in some lines of some breeds, but many of the
cases previously labeled as “idiopathic”, “rage” or “mental
lapse aggression” have been disputed and in some cases
subsequently reclassified. Only when there is no
identifiable stimulus or cause for the behavior, or when an
abnormal EEG is documented, should the diagnosis of
idiopathic aggression be considered. Alterations in
neurotransmitters or receptor sites in the brain may be the
cause of these types of aggression and drug therapy might be
one aspect of treatment.
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Monday thru Friday
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Saturday
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