Introduction to aggressive behavior in dogs & cats
What is aggression?
Aggression is defined as threats or harmful actions directed toward another
individual. In animals, aggressive behavior are a means of communication. Dogs
and cats use aggressive displays, threats and attacks to resolve competitive
disputes over resources (territory, food) or to increase their reproductive
potential. "Aggression" describes the behavior, but does not give
any information about underlying motives or causes. Aggression can result from
a number of motivational states.
How is aggression classified?
Aggression can be subdivided into type based on intended victim or body postures;
alternatively other factors such as the focus of competition, oestrus status
of animals involved, and location of the aggressive encounter may be used to
describe the form of aggression.
The term 'agonistic' refers to conflict or contest behavior in animals (usually
of the same species). These encounters can involve fighting, avoidance, escape,
dominant and submissive gestures and posturing. Aggressive behavior can also
be divided into offensive and defensive aggression. In dogs and cats the supposed
function of the aggression is most commonly used as the basis of classification:
Dominance (status related) related, possessive, protective and territorial,
predatory, fear induced, pain induced, parental, redirected, play, inter-male,
inter-female, and pathophysiological (medical) in origin.
Note that there is no one single cause of aggression. Many factors and stimuli
may combine to push the dog or cat to a point where aggression is displayed.
For example a dog may be territorial as well as fearful of children. This dog
may only exhibit aggression however when it is cornered or tied up and cannot
escape, and a strange child approaches it. When the dog learns that snapping
or growling successfully see off the child, the behavior may be repeated in
other similar situations.
Are aggressive dogs and cats abnormal?
Aggressive behaviors may be "normal", but when they result in human
or animal injury, the behavior is dangerous and unacceptable. Human safety must
always be a primary consideration when discussing aggression. An estimated one
in three children report that they have been "attacked" by a dog and
7% of these reported the incident to the police. This could result in a prosecution
for the owner under the Dangerous Dogs Act 1991. It is important to be able
to identify aggressive dogs and cats to prevent injuries wherever possible.
Some aggression in dogs and cats may have abnormal components and be the direct
result of genetic factors, disease, environmental conditions or experience and
learning. Health problems and degenerative changes may be present and should
be identified whether or not they contribute to the aggressive behavior.
How do dogs communicate their aggressive behaviors?
By watching the body postures and facial expressions of dogs, it is possible
to find an indication of what the dog may do. When a dog is reacting to intrusion,
the first sign may be eye contact as when two dogs meet. In some cases, the
more dominant dog will maintain eye contact, until the more subordinate dog
Prolonged eye contact may be considered a threat by both dominant and subordinate
dogs. Dogs that are acting subordinate by looking away may feel threatened by
continued eye contact and bite out of defensive fear. A dominant and/or assertive
dog can react to continued eye contact by holding the stare and escalating its
aggressive threat. In some dogs a dark iris or hair covering the eyes may make
eye contact difficult to ascertain.
What happens next?
If the intrusion or competition continues, the dog may escalate the threat
by exposing the teeth and snarling. Snarling is not always accompanied by growling
and may only be an upward movement of the lips. Long pendulous lips, long hair
or beards on the face may obscure seeing such lip movements. Ear position in
dogs can also give clues to canine intentions. A subordinate dog will usually
place the ears back as will a fearful dog. An assertive dog will have ears erect.
Again, recognition of these positions can be inhibited by conformation, coat
and cosmetic surgery.
Dogs will also attempt to change the way they position their body in response
to a perceived threat. A dog standing its ground may look "bigger"
by raising the hair along the neck and back, raising the tail in a high position
and slowly wagging its tail from side to side. Other dogs present less of a
threat by looking "smaller", crouching down, tucking the tail between
the legs and even rolling over. Crouching and a lowered body posture in dogs
is an appeasement posture designed to decrease the aggressive threat. While
maintaining either of these postures a dog may be growling, snarling or barking.
These postures can result in a stand off, a decrease or an increase in the aggression.
What does an aggressive cat look like?
Often the first sign is a dilation of the pupils and rapid lateral movements
of the tail. This may be accompanied by the ears being laid back, hissing or
growling. In addition, the cat may "swipe" at the intruder with a
front paw, either with the claws sheathed or exposed. Sometimes the cat will
gather its legs under and appear ready to pounce. If the intruder or competitor
is not too close, or begins to leave, the aggressive encounter may end.
Cats have other more dramatic body postures that signal "go away".
Cats frequently enhance their size and ferocity and make the threat more menacing.
They do this by turning sideways to the intruder, arching their back, holding
the tail upright or straight down, with their fur standing up. They may hiss,
growl and yowl at the same time. In other situations a cat may crouch down,
tail swishing back and forth with the ears tight against the head, again with
an accompanying vocalization. A cat anticipating a serious threat may roll onto
its back with claws extended ready to fend off a foe.
How should I respond to these behaviors?
The distance between the animal and the intruder can be important in determining
the response. This is often called the "flight" distance. If the opponent
is far away the animal may choose to flee, but if the encounter is very close
the animal may choose to fight. If flight is inhibited, as in a dog or cat that
is cornered or tied up, aggression or fight is likely to occur. Most dogs, and
some cats, on their own territory are more likely to fight than retreat. When
approached rapidly, a dog or cat may go through the stages of aggressive behavior
very quickly and bite without the victim being able to react. This happens in
encounters between people and their pets because they may approach too close,
Dogs and cats that are mildly fearful may calm down if the person shows no
fear, waits until the pet settles, and then offers a food reward. Reaching for
a dog or cat, while continuing to advance is most likely to lead to physical
aggression. Standing still and avoiding direct eye contact is often the best
way to reduce aggression in the dog that is chasing. Cats will often flee if
given the opportunity. However some cats will stand their ground and will scratch
or bite if reached for.
In some cases, despite standing still, avoiding further advance or retreating,
the aggression continues. Since aggression depends on the situation, the pet's
motivation, previous experiences and the type of aggression, it will be necessary
for you to provide a detailed history for your veterinary surgeon in order to
establish an accurate diagnosis, and appropriate treatment plan.
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