Aggression

The following advice is an insight only into the various types of dog aggression.

We strongly reccomend that if you are experiencing any aggression problems with your dog, that you seek professional help from an experienced behaviour councillor.

Diagnosing And Treating Aggressive Behaviours In Dogs

Aggression is the most serious and dangerous behaviour problem that dog owners may encounter. 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 behaviourist. In some cases medical conditions can contribute to aggression, therefore before a behaviour consultation it is essential that your dog has a complete physical examination and any necessary blood tests to rule out organ dysfunction. In order to treat the problem effectively, it will first be necessary to determine the type of aggression your dog displays. It may be dominance-related, fear, possessive, protective and territorial, parental, play, redirected, pain induced, pathophysiological or learned. In many cases more than one specific form of aggression may be exhibited.

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 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 show aggression. If the person or animal retreats, acts overly fearful or the pet is harmed or further frightened in any way (e.g. by physical 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 any member. Many cases of fear aggression are seen as combinations or complicating factors of other forms of aggression (dominance, maternal, possessive, etc.). Fearful body postures in conjunction with aggression are diagnostic of fear aggression. Behaviour therapy, possibly in combination with drug therapy, can be used to treat most cases of fear aggression.

What is play aggression and how is it diagnosed?

Play 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 aggression. Although it is a normal behaviour, it can lead to injuries and, if handled incorrectly could lead to more serious forms of aggression as your dog matures.

What is possessive aggression and how is it treated?

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 favourite 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 waste basket, a favoured toy, human food, or a piece of rawhide are some of the items that dogs may aggressively protect.

Treatment must first be directed at preventing possible injury. At first it may be best to confine your dog in a cage so that it cannot gain access to any items that it might pick up and protect. Dogs that protect their food can be given a less palatable diet, and fed in a separate room away from family members. Dogs that protect their treats or toys should have them taken away, and only allowed access to them when alone in the cage or confinement room. When you are available to supervise, a long lead and head collar can be kept attached so that your dog can be prevented from wandering off, and immediately interrupted if it attempts to raid a dustbin or pick up inappropriate objects. Booby traps (including remote alarms or unpleasant tastes) can occasionally be used to teach your dog to stay away from selected objects, but will not be successful alone. Although prevention can help to ensure safety, if the problem is to be corrected your dog will need to be taught to accept approaches and give up objects on command. The goal is to train the dog that it will receive a favoured treat or reward that is even more appealing than the object in its possession. Giving up possession is then associated with gaining something new rather than losing something important. The key to success is to have good control and a well-trained dog.

What is territorial aggression and how can it be treated?

Protective and possessive aggression may be exhibited toward people or other animals that approach the pet’s property (territorial aggression). Generally people and other animals that are less 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 minimised with early socialisation 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. Most dogs will start to alert the family to strangers near the home by barking. However the dog that has been well socialised and under good control can be trained to quickly settle down and relax. For dogs exhibiting territorial aggression, you will need to gain enough control to have your dog sit, stay and when calmed down, take a reward at the front door. Generally a lead and head collar will give the fastest and most effective control. Using a desensitisation and counter-conditioning programme you can begin retraining with low levels of stimuli (such as people arriving in a car, walking past the front of the house, or perhaps even a family member knocking on the door or ringing the bell). The idea is that each time someone arrives at the house or rings the bell, the dog will come to expect a favoured reward (toy, cheese, treat or play session) as soon as it stops barking. Once the dog can be controlled and receives rewards in this environment, gradually more intense stimuli can be used. Sometimes, the initial barking can be disrupted so that the pet can be directed to perform the appropriate behaviour and get its reward.
What is predatory aggression and how can it be treated?

Predation is the tendency to chase and hunt prey. Predatory behaviours 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 predatory tendencies, may display the behaviour when running together with a group of dogs. Although the desire to chase can be reduced by using a head collar combined with desensitising and counter-conditioning programmes in the presence of exciting stimuli, the seriousness of this problem should not be underestimated. It may pose a threat to a variety of humans and animals. Whenever the dog is outdoors it should be confined to an escape proof pen or run, or controlled securely by the owners. A lead and head collar and preferably a muzzle, should be used to help to ensure safety when out for walks.

What is pain-induced aggression and how can it be treated?

Pain-induced aggression is usually elicited by some form of handling or contact that elicits pain or discomfort. However, even if your dog is not exhibiting pain, many medical conditions make a 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 first requires that the medical or painful condition is resolved. Next, you will need to identify the types of handling and situations that have led to aggression in the past. With desensitisation 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 and lead and head collar, may be the safest way to begin the retraining.

What is maternal aggression and how can it be treated?

Maternal aggression is directed toward people or other animals that approach the bitch with her puppies. When bitches have a false pregnancy (pseudopregnancy) they may also become aggressive and begin to protect nesting areas or stuffed toys at the time approximately equivalent to when the puppies would have been born. Once the puppies are weaned and the dog is spayed the problem is unlikely to recur. In the interim, the owners can use a lead or lead 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 desensitisation, counter-conditioning, good control and highly reinforcing rewards, it may be possible to train your dog to accept approach and handling of her puppies.

What is redirected aggression and how can it be treated?

Aggression that is directed towards a person or pet that did not initially evoke the aggression is classified as redirected. 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 not be directly challenged. In some cases a sound alarm, or long lead can be used to safely remove the dog from the situation. If the aggression and arousal does not immediately subside, consider securing your dog in a safe quiet area, until it settles down and will come out for food and gentle affection. Since redirected aggression arises out of other forms of aggression, it is important to identify and treat the initial cause of aggression (e.g. fear, territorial, sibling rivalry, etc.), and to prevent the problem. This can be accomplished by avoiding exposure to the stimulus for the aggression. By keeping a lead and head collar and muzzle on your dog and distracting it with a game or training session the animal can be slowly re-exposed to the problem situation and rapidly desensitised to the exciting stimuli.

What other causes of aggression may be encountered?

Aggression associated with medical disorders may arise at any age, may have a relatively sudden onset and may not fit any canine species typical behaviour. Some medical conditions can, on their own, cause aggression, but in many cases a combination of behavioural factors and medical problems cause the pet to display aggression. It is well known that infections like rabies result in aggression, but other infections, hormonal imbalances like Cushings disease, tumours and a variety of genetic and metabolic factors can instigate, predispose or exacerbate aggressive behaviour. Painful conditions such as dental disease, or arthritis, and medical conditions causing fever, fatigue or sensory loss are likely to increase a pet’s irritability.

In rare circumstances, aggression has no identifiable aetiology and no particular stimuli that initiate the aggressive displays. There may be a genetic propensity to aggression in the lines of certain breeds, but many of the cases previously labelled 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 behaviour following extensive investigation including a thorough neurological assessment should the diagnosis of idiopathic aggression be considered.

What is learned aggression and how can it be treated?

Although learned aggression can refer to dogs that are intentionally trained to act aggressively on command (or in particular situations), learning is also an important component of most other types of aggression. Whenever a dog learns that aggression is successful at removing the stimulus, the behaviour is further reinforced. Some forms of aggression are inadvertently rewarded by owners who, in an attempt to calm the pet and reduce aggression, actually encourage the behaviour with patting or verbal reassurances. Pets that are threatened or punished for aggressive displays may become even more aggressive each time the situation recurs.

Treatment with flooding is intended to teach the pet that the stimulus is not associated with any harm and that aggression will not successfully remove the stimulus. However this technique carries significant risks and with the alternative approach of desensitisation and counter-conditioning, the dog is not only taught that the stimulus is safe, but that it is associated with a reward.

This client information sheet is based on material written by

Sarah Heath, BVSc, DECVBM-CA, MRCVS & Daniel S. Mills, BVSc, PhD, ILTM, CBiol, MIBiol, MRCVS

Used with permission under license. ©Lifelearn Ltd, PO Box 16, Newmarket, Suffolk CB8 7TH.

AGGRESSION – SOCIAL AGGRESSION TOWARDS UNFAMILIAR DOGS

Why is my dog aggressive to other dogs?

Aggression between dogs can result in injury to dogs and/or to the people trying to separate them. The behaviour can consist of growling, snarling, barking, lungeing, snapping and biting. It has many causes including social conflict, owner defence, fear, anxiety or inadequate communication between dogs.

Social 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, high tail and stiff legged approach. Owners may inadvertently reinforce the behaviour by lead tightening and vocal cues. These may also signal to the dog that the impending approach is problematic. Lead restriction does not allow the dog to react with a normal repertoire of responses including body postures, approach and withdrawal. 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 not fights. It is likely therefore that fear, territorial behaviour and/or learned factors contribute to an initial 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 perceives as 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 sort of aggression is very common in aggressive encounters between 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 behaviour may 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 to punish the dog will only serve to heighten the dog’s fear and anxiety in relationship to the stimulus. Good and effective control can help to calm the dog, while owners who have their dogs restrained on a lead (especially with a choke chain) and have poor control often have very defensive dogs. Dogs that are restrained on a lead 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 behaviour has been reinforced. If the owner tries to calm the aggressive dog or distract it with food treats, this may also serve to reward the aggressive behaviour. 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 associated with unpleasant consequences. Many owners, in an attempt to gain more control, then increase the level or type of punishment (e.g. ever more severe jerks on the lead) which further heighten the dog’s arousal and in some cases may lead to retaliation and defensive aggression directed at the owners. 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 arousal 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 socialisation. 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 the prevention of aggression to other dogs.

You must have good control of your dog. Your dog will take contextual cues from you, and may be calmer and less anxious when you are relaxed but in confident control. 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.

For territorial behaviours, it is most important to prevent the dog from engaging in prolonged and out of control aggressive displays both in the home and garden. Aggressive displays include barking, lungeing, fence running, jumping on doors, windows and fences. These types of behaviours should be discouraged and prevented. One important component is teaching your dog a "quiet" command for 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. Leads are essential and the use of head collars and/or muzzles is 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 behaviour in the presence of the stimulus (other dog) can produce favoured rewards. The goal is that the dog learns to associate the approach of other dogs with rewards.

Long term treatment consists of desensitisation (gradual exposure) and counter-conditioning the dog to accept the approach and greeting of other dogs with obedience and rewards. 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 favoured 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 favoured food or toys is essential since the goal is that the dog will learn that receiving these favoured 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 using a lead and head collar, selection of more motivating rewards, and seeking further assistance and guidance from a specialist should be considered. The next steps in desensitisation and counter conditioning rely on a stimulus gradient. In other words your dog needs to be controlled, (preferably with lead 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 less anxious or threatened, and at a sufficient distance that your dog will 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 and learn to greet other dogs; dogs with dominance-related aggression that are trained in this manner do not usually end up greeting other dogs, but learning to walk calmly with their owners and stop initiating fights.

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.

Another way to disrupt the undesirable response and get the dog's attention is to use an air alarm or shaker can. Once the inappropriate behaviour ceases, and you get your dog’s attention, the dog should be redirected to an appropriate behaviour 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 collars are generally the most important tool. Head collars provide enough physical control that the desired behaviour 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, lungeing and aggression can be prevented, and the dog will usually settle down enough to see and respond to the prompt. Rewards can and should be given immediately for a proper response (sitting, heeling), and tension reduced on the lead. If the dog remains under control with the lead slack, the reward (toy, food, affection) should be given, but if the problem behaviour recurs, the lead 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 behaviour. Also since there is no punishment or discomfort that might further aggravate the situation and rewards are not being given until the desired behaviour appears, fear and anxiety will be further reduced.

Are there drugs that can help the treatment programme?

Occasionally, for fear aggressive dogs in particular, certain 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 collar, good owner control and some strong rewards.

This client information sheet is based on material written by

Sarah Heath, BVSc, DECVBM-CA, MRCVS & Daniel S. Mills, BVSc, PhD, ILTM, CBiol, MIBiol, MRCVS

Used with permission under license. ©Lifelearn Ltd, PO Box 16, Newmarket, Suffolk CB8 7TH.

DOGS: AGGRESSION - SIBLING RIVALRY

What is a dominance hierarchy and why is it important to dogs?

Dogs are social animals whose evolutionary history makes them willing and able to live in groups. Group living enabled wolves to work together to obtain food, raise their young and defend their territory. It would be counterproductive for members of a group to fight with each other and risk injury. That would prevent them from working with the group. As a result, dogs have a social structure in which each dog is either dominant (leader) or subordinate in its relationship with each other pack member. This is a "dominance hierarchy". The leader or "alpha" dog is the one that has first access to all the "critical" resources. These resources include food, resting places, mates, territory and favoured possessions. Assertion of dominance by the alpha is generally communicated through facial expressions, body postures and actions. Fighting is rare, since as soon as the subordinate submits or defers to the alpha animal and the alpha gets its way, he or she gives up the challenge.

My dogs have lived together for some time and now they are fighting. Why?

Fights between dogs in the household are often about social status. Social status aggression most often occurs when dogs reach social maturity between 12 and 36 months of age. Fights will be about those resources that are considered important to dogs. Therefore fights may occur over treats, owner attention, priority to greet the owner upon return, sleeping positions, entrances and exits around the home, or movement through tight spaces and during highly arousing situations such as front window disturbances. These fights occur most often between dogs of near equal status and often, but not always, dogs of the same sex. Disputes between female dogs tend to be very severe.

I try to treat my dogs equally, but they still fight. What am I doing wrong?

Trying to treat two dogs as equals will only serve to counter the natural tendency toward a hierarchy. The dog that is the more dominant in a relationship needs to be supported in its position and the more subordinate must be taught to accept the relationship. When you support or encourage the subordinate dog as it tries to gain access to resources such as your attention, the dominant dog may begin to challenge and fight, in an effort to keep the lower ranking dog in its "place". If you then discipline the dominant dog, or pull the dominant dog away, you have favoured, supported and come to the aid of the subordinate dog. This will prolong the dispute.

Why did my dogs begin to fight after my other dog died?

Conflicts may occur between dogs when the dominance status is ambiguous or when they are particularly close in rank. After the decline, illness or death of an older dog, fighting may begin in the remaining dogs even when one is clearly dominant. This is because the older dog may have been dominant to both dogs, and now they are trying to establish new positions. In any case the fighting can be severe and injurious. Although you should generally attempt to allow dogs to resolve their differences on their own you will need to intervene if there is the potential for injury. However, you could be injured due to redirected aggressive attacks, or when you attempt to break up the fight (see below), so extreme care is necessary.

My younger dog always deferred to the older dog, but now they fight.

One scenario that can result in social aggression is when an older, previously dominant dog, is challenged by a younger, more domineering dog. This may happen as the older dog ages, or as the younger dog reaches behavioural maturity at 12 to 36 months. This is often clearly an attempt to alter the existing hierarchy. Sometimes the older dog will acquiesce and things are fine but at other times the owners do not want the change and intervene. In some situations, the older dog will not relinquish the dominant role even though it cannot physically compete with the younger dog. This can result in severe, injurious fights.

How should I break up fighting if it occurs?

This can be a dangerous situation for people and dogs alike. Owners usually try to reach for the collar of the fighting dogs, or if one is small, pick it up. This can result in severe owner injury if the fighting is very intense. If both are wearing leads they can usually be pulled apart. If all else fails, you might be able to break up the fight with a broom, sound alarm or another distraction (such as a fire extinguisher). If using an extinguisher, then care must be taken to avoid damaging the eyes with either a powerful spray or the cold gas. Reaching for the dog is usually the worst thing to do, as you could be injured. It is often useful to have a length of stick to defend yourself, should a dog turn on you. This is used to direct the dogs bite to a harmless area i.e. the stick, NOT to hit the dog.

When people intervene in dog fights, redirected aggression is possible. Aggression (growl, snarl or bite) can be redirected to a person, animal or object other than that which evoked the aggression. If during the course of a dog fight, you pick up one of the dogs, the other may continue to attack and direct it at you.

What should I do when one of my dogs challenges another?

Aggression between household dogs can be difficult to treat. You will need to identify the subordinate dog, and ensure that you are not encouraging the subordinate dog to challenge the more dominant. It is critical that you never come to the aid of the subordinate against the more dominant. If left alone, the dogs will often use posturing and threats to end encounters without injury. If one dog backs down, the problem may be resolved. However, when neither dog is willing to give up the contest (as in a young dog challenging an older dog in the home), fighting will usually result.

A common owner error is the desire to make life "fair". This often results in owners allowing subordinate dogs access to resources, such as attention, treats, toys, or entry into territory that they would not normally have. Usually the subordinate dog would not behave in a manner that would challenge the dominant when no one is around to “protect” it. If you encourage or protect the subordinate dog, it may exploit the situation, and the dominant dog may become aggressive in order to assert its control. If you then punish the dominant dog for aggression, the subordinate dog learns it can engage in prohibited behaviour while the owner is present. This is why, in many households, there is no fighting when the owners are gone. The subordinate is aware of the situational basis to the hierarchy, and does nothing to challenge the dominant dog, unless the owners are around to support them.

How can I treat this problem?

Although the dominance relationship between the two dogs must be dealt with, the first step is for the owner to gain complete control over both dogs. Your presence and commands should be sufficient to prevent and control all dominance challenges between dogs. Control of each dog is achieved through the use of verbal commands, by leaving a lead and head collar attached for immediate control, and by controlling access to all rewards including food treats, toys and games. This should be given at your instigation not that of the dogs and toys should not be left down the whole time. Attention on demand not only encourages situations where one dog may challenge the other, but also allows your dogs to control you. Inattention on demand teaches the dogs that all rewards are provided only when you choose, and reduces or eliminates those situations where challenges might occur. Head collar with lead control and obedience-reward based training of each dog should first be done separately. With a head collar and remote lead on each dog you will have effective control, and a means of controlling and separating the dogs if needed. With control of the head and mouth, aggressive threats can be curtailed and either dog can be placed in a subordinate posture, by pulling up on the lead, closing the mouth or pulling the head sideways so that the dog’s gaze is averted.

Treatment should be designed to identify and support the dominant dog. In most cases this is the younger, larger, more physically capable dog. Often, this is also reported to be the aggressor. You must allow the dominant dog priority in all instances of potential competition. This might include the opportunity to go outside, to come in, or to receive food or owner attention and affection. If you are petting the dominant dog and the subordinate dog approaches, make it wait. Avoid all circumstances that elicit aggression. If the more dominant dog approaches or challenges the subordinate dog and the subordinate dog assumes a subordinate posture, the owners are not to intervene as long as the dominant dogs stop. If the dogs are likely to fight when you are away or at homecomings, separate the dogs whenever you are out, or are not able to supervise.

On other occasions, neither dog is willing to be subordinate. This could be due to a challenge to the hierarchy as a younger dog matures, as an older dog becomes sick or aged, when a new dog is introduced into the home, or when one dog is not clearly dominant to the other. It is important to recognise canine body language and low level threats such as eye contact, snarls or low growls. Keep records of threats, attacks, or tension producing situations. An owner must have excellent control over both dogs in order to succeed. To facilitate treatment, decrease the chances of injuries and increase owner control, a remote lead can be left attached to one or both dogs. Often the best form of owner control is to fit and train each dog with a head halter, and to leave a lead and head halter on each dog when they are together (under the owner’s supervision).

Once you have gained sufficient control over both dogs, and have identified the more dominant, you will need to deal with the circumstances that might elicit aggression. Greetings should be calm rather than overly exciting, and both dogs may need to be ignored. Treats are avoided and rawhides or other delicious things are not given unless the dogs are separated or on lead. Movement through tight spaces is avoided or controlled. You must be present to ensure that the dominant dog gains preferential access to food, resting places, territory, owner attention and treats. Commands and rewards or the lead and halter can be used to ensure that the subordinate does not challenge, and that the dominant does not continue to show aggression once the subordinate submits. Getting the dogs together without incident can be accomplished most easily when the dogs are distracted and when a confrontation is unlikely, such as during walks or feeding. It is usually best to have two individuals to walk the dogs (each person controls one dog) and not to allow them to forge in front of one another. During feeding, keep the dogs at a distance, far enough apart that they do not show aggression. Slowly the dishes are moved closer together as long as the dogs do not react. The food serves as a reward in this situation. If the dogs react, the food bowls are moved further apart. When the owner is not home or supervising the dogs, the dogs are separated or caged.

Well-fitting and secure basket muzzles could be left on each dog to increase safety while the dogs are together. They can also be used to "proof" the training, by putting the dogs together in situations that previously led to aggression. Drug therapy for one or both dogs may also be useful.

Can social aggression always be corrected?

At times aggression may persist despite owner control and intervention. In those cases alternative living arrangements for one of the animals may need to be made.

This client information sheet is based on material written by

Sarah Heath, BVSc, DECVBM-CA, MRCVS & Daniel S. Mills, BVSc, PhD, ILTM, CBiol, MIBiol, MRCVS