AGGRESSION – SOCIAL AGGRESSION TO
UNFAMILIAR DOGS
UNFAMILIAR DOGS
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Why is my dog aggressive towards other dogs?
Aggression between dogs can result in injury to dogs and/or to the
people trying to separate them. The behavior can consist of growling,
snarling, barking, lunging, snapping and biting.
Why would my dog fight with dogs he has never
met?
Aggression between unfamiliar dogs can be due to dominance, fear, or
protective behavior over territory or owner.
Dominance motivated aggression
This aggression can be elicited by dominant gestures or postures from
either dog. These can include placing head or feet, on the back of the
other dog, dominant body postures such as eye contact, and high tail
and stiff legged approach. Owners may inadvertently reinforce the
behavior by leash tightening and vocal cues. These may signal to the
dog that the impending approach is problematic. Unfortunately leash
restriction does not allow the dog to react with a complete rate and
range of responses including body postures, approach and withdrawal.
Additionally, this behavior can be elicited by smaller dogs that
repeatedly "attack" larger dogs that are attempting to avoid interaction.
Dogs of near equal dominance and those of the same sex are most
likely to compete for dominance. Some extremely bold or assertive
dogs will fight rather than back down when challenged. Although
dominance challenges may be a source of aggression when two dogs
are meeting each other for the first time, most dominance hierarchies
are established with posturing and no fights. It is likely therefore that
fear, territorial behavior and learned components, would contribute to an
attack. Dominant aggressive dogs may be over-assertive and/or
overprotective if the owners do not have good control or have taken a
subordinate position in relationship to the dog.
Aggression between dogs can result in injury to dogs and/or to the
people trying to separate them. The behavior can consist of growling,
snarling, barking, lunging, snapping and biting.
Why would my dog fight with dogs he has never
met?
Aggression between unfamiliar dogs can be due to dominance, fear, or
protective behavior over territory or owner.
Dominance motivated aggression
This aggression can be elicited by dominant gestures or postures from
either dog. These can include placing head or feet, on the back of the
other dog, dominant body postures such as eye contact, and high tail
and stiff legged approach. Owners may inadvertently reinforce the
behavior by leash tightening and vocal cues. These may signal to the
dog that the impending approach is problematic. Unfortunately leash
restriction does not allow the dog to react with a complete rate and
range of responses including body postures, approach and withdrawal.
Additionally, this behavior can be elicited by smaller dogs that
repeatedly "attack" larger dogs that are attempting to avoid interaction.
Dogs of near equal dominance and those of the same sex are most
likely to compete for dominance. Some extremely bold or assertive
dogs will fight rather than back down when challenged. Although
dominance challenges may be a source of aggression when two dogs
are meeting each other for the first time, most dominance hierarchies
are established with posturing and no fights. It is likely therefore that
fear, territorial behavior and learned components, would contribute to an
attack. Dominant aggressive dogs may be over-assertive and/or
overprotective if the owners do not have good control or have taken a
subordinate position in relationship to the dog.
Territorial aggression toward other dogs
This aggression is primarily exhibited when unfamiliar dogs are on the resident dog’s property, or what
the aggressor considers his territory. Some dogs get highly aroused at the sight of other dogs on their
territory and may jump fences, or go through windows or doors to get to the intruder.
Fear based aggression toward unfamiliar dogs
This aggression is very common in aggressive encounters with other dogs. The diagnosis is made
based on the body postures and reaction of the dog when faced with another dog. The fearful dog will
often have the tail tucked, ears back and may lean against the owner or attempt to get behind them. They
may be barking at the approaching dog and backing up at the same time. Often the dog is avoiding eye
contact. This behavior can be precipitated by previous aggressive attacks from which the dog could not
escape and sustained injury. Owners that try and calm their aggressive dog may serve to reinforce the
aggression, while those that try and punish the dog will only serve to heighten the dog’s fear and anxiety
in relationship to the stimulus. Good control can help to calm the dog, while owners who have their dogs
restrained on a leash (especially with a choke or pinch collar) and have poor control often have highly
defensive dogs. Dogs that are restrained on a leash or tied up are more likely to display aggression
when frightened, because they cannot escape.
Learned components of aggression
Learning and conditioning aggravate most forms of inter-dog aggression. Should threats or aggression
result in the retreat (or removal by the owner) of the other dog, the behavior has been successful. If the
owner tries to calm the aggressive dog or distract it with food treats, this may only serve to reward the
aggressive behavior. One of the most common mistakes is to punish the dog that is aggressive toward
other dogs. This usually serves to heighten the dog’s arousal, and teaches the dog that the stimulus
(other dog) is indeed associated with unpleasant consequences. Many owners, in an attempt to gain
more control, then increase the level or type of punishment (e.g. prong collars) which further heighten the
dog’s arousal and in some cases may lead to retaliation and defensive aggression toward the owners.
And, if the dog to dog interaction results in pain or injury to one or both dogs, the dogs will quickly learn to
become more fearful and aggressive at future meetings. In short, if the owners cannot successfully
control the dog and resolve the situation without heightening the dog’s anxiety or increasing its fear, the
problem will progress with each subsequent exposure.
How can I prevent my dog from becoming aggressive with other
dogs?
Prevention starts with puppy training and socialization. Early and frequent association with other dogs
will enable your pet to learn proper interactions and reactions to other dogs. This can be very helpful in
prevention of aggression to other dogs.
You must have good control of your dog. This means that your dog will take contextual cues from you, and
may be calmer and less anxious in the presence of new stimuli. Moreover, the dog should reliably
respond to commands to ‘sit’, ‘stay’ and ‘quiet’. If necessary, the dog may need a head halter to give you
additional control. When in situations where the dog may encounter other dogs, a leash is necessary.
For territorial behaviors, what is most important is to prevent the dog from engaging in prolonged and out
of control aggressive displays both in the home and yard. Aggressive displays include barking, lunging,
fence running, jumping on doors, windows and fences. These types of behaviors should be discouraged
and prevented. One important component is teaching your dog a ‘quiet’ command for barking (see
handout on Barking).
My dog is already aggressive to other dogs. What can I do?
First and foremost, you must have complete control over your pet. This not only serves to calm the dog
and reduce its anxiety, but also allows you to successfully deal with each encounter with other dogs.
Leashes are essential and the use of head collars and/or muzzles are strongly recommended for dogs
that will be in situations with multiple dogs.
Begin by establishing reliable responses to basic obedience commands. If the dog cannot be taught to
‘sit’, ‘stay’, ‘come’ and ‘heel’, in the absence of potential problems, then there is no chance that the dog
will respond obediently in problematic situations. Reward selection can be critical in these cases, since
the dog needs to be taught that obedient behavior in the presence of the stimulus (other dog) can earn
the dog-favored rewards. The goal is that the dog learns to associate the approach of other dogs with
rewards.
Long term treatment consists of desensitization (gradual exposure) and counter-conditioning the dog so
that the approach of the other dogs leads to a positive emotional response. In training terms the dog
must be taught to display an appropriate, acceptable response when other dogs approach (e.g. ‘sit’,
‘watch’, ‘relax’) which can be reinforced (differential reinforcement or response substitution). This must
be done slowly, beginning with situations where the dog can be successfully controlled and rewarded
and very slowly progressing to more difficult encounters and environments. The first step is to perform
training for its favored rewards, in a situation where there are no dogs present and the owner is
guaranteed success. Food or toy prompts can be used at first, but soon the rewards should be hidden
and the dog rewarded intermittently. The selection of favored food or toys is essential since the goal is
that the dog will learn that receiving these favored rewards is contingent on meeting other dogs.
Once the dog responds quickly and is receiving rewards on an intermittent basis, training should
progress to low-level exposure to other dogs. If the owner’s training and the rewards are not sufficient to
control the dog in the absence of the other dogs, then utilizing a leash and head collar, selection of more
motivating rewards, and seeking the assistance and guidance of a behaviorist should be considered.
The next steps in desensitization and counter-conditioning rely on a stimulus gradient. In other words your
dog needs to be controlled, (preferably with leash and head halter) and respond to commands and
rewards in the presence of gradually more intense stimuli.
Begin with a calm, and well-controlled second dog, in an environment where your dog is least anxious or
threatened, and at a sufficient distance to get your dog to respond to your commands. Gradually the dog
is exposed to dogs at closer distances and in more familiar locations. Using the head halter and a
prompt (reward prompt, set of keys) it should be possible to keep the dog focused on the owner and
sufficiently distracted. While dogs with fear aggression may improve dramatically, dogs with dominance-
related aggression that are trained in this manner usually do not greet other dogs, but should walk calmly
with their owners and not initiate fighting behavior.
Dogs that are exhibiting territorial aggression should be retrained in much the same manner, but the
gradient of stimuli will need to be adjusted. Begin in the front hall or on the front porch with no other dogs
around. Then with the dog controlled in the hall or on the porch, other dogs could be brought to the
perimeter of the property. Over subsequent training sessions, the dogs could be brought closer to your
dog, or your dog could be moved closer to the other dog. (See our handout on Behavior Modification -
desensitization, counter-conditioning, differential reinforcement and flooding).
Another way to disrupt the undesirable response and get the dog’s attention is to use an air horn, shake
can or citronella spray collar. In fact, if the dog barks prior to the aggressive display, a citronella spray
bark collar will be activated by the dog’s barking insuring immediate timing and disruption. Once the
inappropriate behavior ceases, and you get your dog’s attention, the dog should be redirected to an
appropriate behavior such as play. The greeting should be repeated, until no threats or aggression are
observed.
Success can be achieved in a number of ways, but head halters are generally the most important tools.
Head halters provide enough physical control that the desired behavior can be achieved (sit, heel) since
pulling up and forward, turns the head toward the owner and causes the dog to retreat into a sit position.
With the dog’s head oriented toward the owner and away from the other dog, lunging and aggression
can be prevented, and the dog will usually settle down enough to see and respond to the prompt. A
second hand can guide the muzzle under the chin to insure eye contact and help to calm the dog.
Rewards can and should be given immediately for a proper response (sitting, heeling), by releasing
tension on the leash. If the dog remains under control with the leash slack, the reward (toy, food,
affection) should be given, but if the problem behavior recurs, the leash should be pulled and then
released as many times as is necessary to get and maintain the desired response. The dog’s anxiety
quickly diminishes as it learns that the other dog is not to be feared, that there is no opportunity to
escape, that its responses will not chase away the other dog, that responding to the owner’s commands
will achieve rewards, and that the owner has sufficient control to achieve the desired behavior (which
further calms the dog). Also since there is no punishment or discomfort that might further aggravate the
situation and rewards are not being given until the desired behavior appears, fear and anxiety will be
further reduced.
Are there drugs that can help the treatment program?
Occasionally, for fear aggressive dogs in particular, anti-anxiety drugs may help to calm the dog enough
so that the retraining session is successful. For situations where the problem has become highly
conditioned and intense, antidepressants may be useful for regaining control. In most cases however, the
best calming influence is a head halter, good owner control and some strong rewards.
This client information sheet is based on material written by Debra Horwitz, DVM, DACVB and
Gary Landsberg, DVM, DACVB. © Copyright 2002 Lifelearn Inc. Used with permission under license.
October 31, 2007.
This aggression is primarily exhibited when unfamiliar dogs are on the resident dog’s property, or what
the aggressor considers his territory. Some dogs get highly aroused at the sight of other dogs on their
territory and may jump fences, or go through windows or doors to get to the intruder.
Fear based aggression toward unfamiliar dogs
This aggression is very common in aggressive encounters with other dogs. The diagnosis is made
based on the body postures and reaction of the dog when faced with another dog. The fearful dog will
often have the tail tucked, ears back and may lean against the owner or attempt to get behind them. They
may be barking at the approaching dog and backing up at the same time. Often the dog is avoiding eye
contact. This behavior can be precipitated by previous aggressive attacks from which the dog could not
escape and sustained injury. Owners that try and calm their aggressive dog may serve to reinforce the
aggression, while those that try and punish the dog will only serve to heighten the dog’s fear and anxiety
in relationship to the stimulus. Good control can help to calm the dog, while owners who have their dogs
restrained on a leash (especially with a choke or pinch collar) and have poor control often have highly
defensive dogs. Dogs that are restrained on a leash or tied up are more likely to display aggression
when frightened, because they cannot escape.
Learned components of aggression
Learning and conditioning aggravate most forms of inter-dog aggression. Should threats or aggression
result in the retreat (or removal by the owner) of the other dog, the behavior has been successful. If the
owner tries to calm the aggressive dog or distract it with food treats, this may only serve to reward the
aggressive behavior. One of the most common mistakes is to punish the dog that is aggressive toward
other dogs. This usually serves to heighten the dog’s arousal, and teaches the dog that the stimulus
(other dog) is indeed associated with unpleasant consequences. Many owners, in an attempt to gain
more control, then increase the level or type of punishment (e.g. prong collars) which further heighten the
dog’s arousal and in some cases may lead to retaliation and defensive aggression toward the owners.
And, if the dog to dog interaction results in pain or injury to one or both dogs, the dogs will quickly learn to
become more fearful and aggressive at future meetings. In short, if the owners cannot successfully
control the dog and resolve the situation without heightening the dog’s anxiety or increasing its fear, the
problem will progress with each subsequent exposure.
How can I prevent my dog from becoming aggressive with other
dogs?
Prevention starts with puppy training and socialization. Early and frequent association with other dogs
will enable your pet to learn proper interactions and reactions to other dogs. This can be very helpful in
prevention of aggression to other dogs.
You must have good control of your dog. This means that your dog will take contextual cues from you, and
may be calmer and less anxious in the presence of new stimuli. Moreover, the dog should reliably
respond to commands to ‘sit’, ‘stay’ and ‘quiet’. If necessary, the dog may need a head halter to give you
additional control. When in situations where the dog may encounter other dogs, a leash is necessary.
For territorial behaviors, what is most important is to prevent the dog from engaging in prolonged and out
of control aggressive displays both in the home and yard. Aggressive displays include barking, lunging,
fence running, jumping on doors, windows and fences. These types of behaviors should be discouraged
and prevented. One important component is teaching your dog a ‘quiet’ command for barking (see
handout on Barking).
My dog is already aggressive to other dogs. What can I do?
First and foremost, you must have complete control over your pet. This not only serves to calm the dog
and reduce its anxiety, but also allows you to successfully deal with each encounter with other dogs.
Leashes are essential and the use of head collars and/or muzzles are strongly recommended for dogs
that will be in situations with multiple dogs.
Begin by establishing reliable responses to basic obedience commands. If the dog cannot be taught to
‘sit’, ‘stay’, ‘come’ and ‘heel’, in the absence of potential problems, then there is no chance that the dog
will respond obediently in problematic situations. Reward selection can be critical in these cases, since
the dog needs to be taught that obedient behavior in the presence of the stimulus (other dog) can earn
the dog-favored rewards. The goal is that the dog learns to associate the approach of other dogs with
rewards.
Long term treatment consists of desensitization (gradual exposure) and counter-conditioning the dog so
that the approach of the other dogs leads to a positive emotional response. In training terms the dog
must be taught to display an appropriate, acceptable response when other dogs approach (e.g. ‘sit’,
‘watch’, ‘relax’) which can be reinforced (differential reinforcement or response substitution). This must
be done slowly, beginning with situations where the dog can be successfully controlled and rewarded
and very slowly progressing to more difficult encounters and environments. The first step is to perform
training for its favored rewards, in a situation where there are no dogs present and the owner is
guaranteed success. Food or toy prompts can be used at first, but soon the rewards should be hidden
and the dog rewarded intermittently. The selection of favored food or toys is essential since the goal is
that the dog will learn that receiving these favored rewards is contingent on meeting other dogs.
Once the dog responds quickly and is receiving rewards on an intermittent basis, training should
progress to low-level exposure to other dogs. If the owner’s training and the rewards are not sufficient to
control the dog in the absence of the other dogs, then utilizing a leash and head collar, selection of more
motivating rewards, and seeking the assistance and guidance of a behaviorist should be considered.
The next steps in desensitization and counter-conditioning rely on a stimulus gradient. In other words your
dog needs to be controlled, (preferably with leash and head halter) and respond to commands and
rewards in the presence of gradually more intense stimuli.
Begin with a calm, and well-controlled second dog, in an environment where your dog is least anxious or
threatened, and at a sufficient distance to get your dog to respond to your commands. Gradually the dog
is exposed to dogs at closer distances and in more familiar locations. Using the head halter and a
prompt (reward prompt, set of keys) it should be possible to keep the dog focused on the owner and
sufficiently distracted. While dogs with fear aggression may improve dramatically, dogs with dominance-
related aggression that are trained in this manner usually do not greet other dogs, but should walk calmly
with their owners and not initiate fighting behavior.
Dogs that are exhibiting territorial aggression should be retrained in much the same manner, but the
gradient of stimuli will need to be adjusted. Begin in the front hall or on the front porch with no other dogs
around. Then with the dog controlled in the hall or on the porch, other dogs could be brought to the
perimeter of the property. Over subsequent training sessions, the dogs could be brought closer to your
dog, or your dog could be moved closer to the other dog. (See our handout on Behavior Modification -
desensitization, counter-conditioning, differential reinforcement and flooding).
Another way to disrupt the undesirable response and get the dog’s attention is to use an air horn, shake
can or citronella spray collar. In fact, if the dog barks prior to the aggressive display, a citronella spray
bark collar will be activated by the dog’s barking insuring immediate timing and disruption. Once the
inappropriate behavior ceases, and you get your dog’s attention, the dog should be redirected to an
appropriate behavior such as play. The greeting should be repeated, until no threats or aggression are
observed.
Success can be achieved in a number of ways, but head halters are generally the most important tools.
Head halters provide enough physical control that the desired behavior can be achieved (sit, heel) since
pulling up and forward, turns the head toward the owner and causes the dog to retreat into a sit position.
With the dog’s head oriented toward the owner and away from the other dog, lunging and aggression
can be prevented, and the dog will usually settle down enough to see and respond to the prompt. A
second hand can guide the muzzle under the chin to insure eye contact and help to calm the dog.
Rewards can and should be given immediately for a proper response (sitting, heeling), by releasing
tension on the leash. If the dog remains under control with the leash slack, the reward (toy, food,
affection) should be given, but if the problem behavior recurs, the leash should be pulled and then
released as many times as is necessary to get and maintain the desired response. The dog’s anxiety
quickly diminishes as it learns that the other dog is not to be feared, that there is no opportunity to
escape, that its responses will not chase away the other dog, that responding to the owner’s commands
will achieve rewards, and that the owner has sufficient control to achieve the desired behavior (which
further calms the dog). Also since there is no punishment or discomfort that might further aggravate the
situation and rewards are not being given until the desired behavior appears, fear and anxiety will be
further reduced.
Are there drugs that can help the treatment program?
Occasionally, for fear aggressive dogs in particular, anti-anxiety drugs may help to calm the dog enough
so that the retraining session is successful. For situations where the problem has become highly
conditioned and intense, antidepressants may be useful for regaining control. In most cases however, the
best calming influence is a head halter, good owner control and some strong rewards.
This client information sheet is based on material written by Debra Horwitz, DVM, DACVB and
Gary Landsberg, DVM, DACVB. © Copyright 2002 Lifelearn Inc. Used with permission under license.
October 31, 2007.
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| 763-689-0095 |
| Cambridge VetCare Animal Clinic Cambridge, MN |
Clinic Hours:
Monday - Friday: 8am - 6pm
Saturday - 8am - 12pm
Sunday - Closed
Monday - Friday: 8am - 6pm
Saturday - 8am - 12pm
Sunday - Closed
This dog is
wearing a Gentle
Leader harness.
This product
prevents pulling.
wearing a Gentle
Leader harness.
This product
prevents pulling.