Dog: Aggression - Sibling Rivalry

puppies fightingWhat 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 enables a range of co-operative activities to take place efficiently as long as everyone knows what is expected of them. For example, group hunting would be useless if everyone just did their own thing and it is counterproductive for members of a group to fight with each other and risk injury. Dogs often learn through play, visual signals and other circumstances, who is the best to take the lead in a given situation and so will often defer to each other depending on the circumstances. Who gives way to who, and in what circumstances, results in what we call a "dominance hierarchy", although it would perhaps be better called a deference hierarchy as dominance is normally given rather than asserted.

Dogs recognise the difference between humans and other dogs in their own social group and will have their own hierarchy amongst themselves. This hierarchy may be resource dependent, i.e. who takes precedence will vary with the specific resource. If there are new circumstances, individuals may need to be reminded of the rules and in these instances you may see the assertion of dominance by individuals in an attempt to elicit signs of deference from the other individuals. This is generally communicated through subtle facial expressions, body postures and actions, with overt aggression being quite rare. If you watch dogs carefully, you will generally see much more avoidance than you will assertion. Nonetheless, problems of miscommunication can arise between dogs in the same household and can be very distressing for dogs and owners alike.

Such aggression may be a sign of social instability within the group and if so it needs to be managed within this broader context of establishing a stable social situation, rather than seen as just a behaviour which needs to eliminated. It is also important to consider any emotional component to the problem and to assess the emotional state of each of the dogs involved. In some cases the behavioural symptoms may be the result of emotional reactions from one or both of the dogs rather than as a direct consequence of the relationship between them. This possibility needs to be considered and the emotional reactions of each of the dogs will need to be assessed and treated as necessary. 

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

Fights between familiar dogs in the household are often a sign of social instability, this might be because of a normal change in the social dynamics of the group, for example one individual may have reached social maturity (typically this occurs much later than sexual maturity between 12-36 months of age), or one individual may be starting to become infirm (for this reason a careful medical evaluation of the dog involved is essential). Fights will usually be focused around those resources that are considered important to dogs. Therefore fights may occur over treats, owner attention (i.e. you), priority to greet you when you come home, sleeping positions, entrances and exits around the home, or movement through tight spaces and during highly arousing situations such as when going out for a walk, etc. The fights may indicate that the dogs have not established who should take precedence. But it is important to remember that apparent aggression can also arise in high arousal situations as a result of anxiety and uncertainty. Dogs that are not socially confident can react to high arousal by becoming more insecure and this can result in redirection of arousal driven aggressive responses onto the other dog in the household. A careful assessment of the underlying emotional state of both dogs is therefore very important before a treatment plan is begun.

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

This is a very common statement from owners, who want things to be fair, but trying to treat two dogs as equals will only serve to counter the natural tendency toward a hierarchy. Similarly, the problem can be worsened by inappropriate intervention, such as telling one of the dogs off – remember that the dog who physically starts the fight is not necessarily the “aggressor”. In simple terms the dog that is naturally confident in a relationship needs to be supported in its position and the less confident one must be taught that it is rewarding to accept the relationship in those terms. It is important to view things from a dog’s perspective rather than a human one, this is not about being unfair or cruel to one dog, it is about giving guidance. If you support or encourage the less confident dog as it tries to gain access to resources such as your attention, you may increase its expectations to unrealistic levels that cannot always be attained. This may result in tension between your dogs and if you then discipline the confident dog, or pull it away, you may inadvertently increase arousal and make conflict more likely. This form of human intervention can prolong the tension between the dogs since any confidence that the low confidence individual displays is false and dependent on your presence. It is generally advisable to allow dogs to resolve their differences on their own and to remember that posturing and low level grumbling, without physical attacks are normal canine interactions. However, you will need to intervene if it seems to be persisting or you are concerned that there is the potential for injury. If this is the case the situation is serious enough to warrant professional intervention and you should ask your veterinary surgeon for advice.

How should I break up fighting if it occurs?

When physical fights break out between dogs it 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. The general rule is to avoid intervening in a dog fight in any way that involves physical contact with either dog. If both are wearing leads you can try to use these to pull the dogs apart and if you have an item such as a broom you can attempt to insert this between the dogs hopefully encouraging one of them to take hold of the item, rather than of each other. If neither of these approaches is successful you can try to break up the fight with a 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. If you do break up the fight using a remote signal then it is often useful to have a length of stick/broom handle for the dogs to bite on since they can become highly aroused and frustrated as they separate. The stick is used to direct the dog’s bite to a harmless area i.e. the stick, NOT to hit either of the dogs.

When people intervene in dog fights, it is possible for the aggression of the dogs to 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 its behaviour toward you. In addition if you lift one of the dogs up into your arms you are placing the dog close to your upper torso and face and you may induce a potentially dangerous aggressive attack on you as the dog attempts to regain contact with the other dog.

What should I do when one of my dogs is overtly aggressive to another?

Aggression between household dogs can be difficult to treat, and you should not be afraid to seek professional behavioural support. It is very important to assess the emotional state of both of the dogs and you may need professional help to do this accurately.

1. You will need to identify the preferred relationship between your dogs and the potential for this relationship to be stable. For example, if the problem has arisen because one dog has recently reached social maturity and it is now fitter and bigger than the other dog, or one dog is ageing and becoming frail then it is probably only a matter of time before the roles are successfully reversed and the relationship re-stabilised. This assessment can be difficult to do, as it may be your longest serving companion that you have to teach to step down and give up some of his previous privileges. However, if the dispute is between physically similar individuals who are in dispute over similarly valued resources the potential for spontaneous resolution is very poor.

2. You need to carefully examine your own behaviour towards the disputing dogs and it is important to ensure that you are not inadvertently encouraging the less confident dog to challenge the other individual. It is critical that you resist the temptation to come to the aid of the less confident dog as you run the risk of inducing a learned confidence that is dependent on your presence. This can lead to serious miscommunication between the dogs and run the risk of serious confrontation when you are not there to uphold the less confident dog. Aggression will be minimised when the difference in social status is most clear, and intervention to support the underdog, will only blur this distinction and make matters worse. It is worth considering if there is any evidence of a problem when you are not there. 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 with a young dog challenging an older dog in the home) fighting will usually result.

"You need to carefully examine your own behaviour towards the disputing dogs and it is important to ensure that you are not inadvertently encouraging the less confident dog to challenge the other individual."

If you punish the more confident dog for displays of aggression, even if it is the initiator and you feel that the other dog did nothing to deserve this, the less confident dog may learn that success is more likely when you are present and be more likely to challenge the other dog. This is why, in many households, there is no fighting when the owners are not present. The less confident dog is aware of the situational basis to its success, and does nothing to challenge the other dog, unless the owners are around to support it. Equally the more confident dog learns that displays of aggression are not heeded by the other dog if the owner is present and learns to suppress its aggressive behaviour in the owner’s presence. However, the reality is that if the more confident dog feels the need to express aggression, it is because more subtle ways of communication with the other dog have failed, and so it is important to support this dog in its attempts to bring clarity to the situation rather than suppress the situation.

puppies fighting over a toyHow can I treat this problem?

Aggression is a normal behaviour and therefore it is never cured but it can be managed to minimise risk.

1.  Sometimes the circumstances in which aggression is displayed are quite predictable and it is important to avoid these circumstances as far as possible. For example, 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. If the dogs are aggressive in association with feeding it is sensible to keep the dogs at a distance (far enough apart that they do not show aggression) and if necessary feed them in different rooms with the doors in between shut until they are finished.

2.  In other cases the aggression does not appear to be predictable in terms of the circumstances and it is important for owners to learn to recognise canine body language which indicates that all is not well between the two dogs. Low level threats such as eye contact, snarls or low growls may help you to predict problematic situations. Keep records of threats, attacks, or tension producing situations as this will help you to more accurately assess the relationship between the dogs in the future. 

3.  If there is any degree of unpredictability to the behaviour then it can be very helpful to be able to gain control over the dogs without risking any physical intervention between them. This can be achieved with the help of a trailing houseline, with or without a head collar. The idea is to use the line to gain physical control and separate the dogs. It will be most effective in the early stages of confrontation so the ability to read subtle signs of impending conflict is very important. The addition of the head collar can enable the owner to control the head and move the head in order to avert eye contact which may be useful in some situations. It is very important that dogs are never left with a headcollar and/or  trailing houseline attached if they are not being supervised.

4.  In order to stabilise the relationship between the two dogs it is important for each of them to feel secure in their relationship with you. If both of the dogs trust you then your presence and instruction should be sufficient to prevent and/or control any challenges that may arise between themselves. This is achieved through the use of verbal obedience commands and by controlling access to rewards including food treats, toys and games. Teach each of the dogs that the good things in life are available at your instigation. Do not leave toys or valuable items, which may encourage the dogs to challenge one another, lying around. Resist the temptation to give attention on demand since this may encourage situations where both dogs ask for your attention at the same time and thereby increase the risk that one dog may challenge the other.

"In order to stabilise the relationship between the two dogs it is important for each of them to feel secure in their relationship with you."

5.  Treatment of underlying social issues is necessary in order to stabilise the relationship between the two dogs. This will involve owners being consistent in their interactions with the dogs and resisting the temptation to treat them as equals. Dogs naturally live in a hierarchical structure and it is natural for them to show deference to other individuals. It is important therefore to identify the more confident dog in the household and to support natural communication between the dogs. In most cases the most confident dog is the younger, larger, more physically capable dog. Often, this dog is also reported to be the aggressor and therefore the dog that the owners feel less inclined to support. 

a. Try to avoid giving overt attention to either dog in the early stages of the treatment programme.

b. If the more confident dog approaches or challenges the other dog and it responds with a display of deferent behaviour, you should not intervene as long as the confident dog does not escalate the exchange.

c. When there are two dogs in the household it is sensible to ensure that all greetings between owners and dogs are as calm as possible. High arousal during greeting can often be a catalyst for confrontational behaviour. 

dog toysd. High value treats, such as rawhides or other highly palatable foods, should not be given to the dogs unless they are separated or on a lead.

e. Movement through tight spaces with the two dogs should be avoided or controlled. 

f. Getting the dogs together without incident can be accomplished most easily when the dogs are distracted and when a confrontation is unlikely, for example during walks. It is usually best to have two individuals walking the dogs (each person controls one dog) and not to allow them to forge in front of one another. The dogs can be brought together slowly, and their body language watched. They should be rewarded for appropriate behaviour i.e. if the confident dog stares at the other, the less confident individual should avert its gaze or be encouraged to do so with the head collar. The more confident individual should then break off the encounter. If either of the dogs begin to get more aroused or the encounter is not self limiting you should use the leads and head collars to slowly but steadily move the dogs away from one another.

6.  Well-fitting and secure basket muzzles may be required for each dog to increase safety if the dogs are together. Muzzles should only be used once the dog has been successfully introduced to wearing one in positive situations. Once you are happy that the dogs can be introduced successfully when fitted with a houseline and/or headcollar it will be time to gradually introduce the dogs in previously problematic situations without the safety of the line. At this stage the muzzle will be very important. Always start the process with the least arousing situations and make sure that you are confident about reading your dogs’ body language. If you are in any doubt ask for professional assistance during this process.

7.  In some cases drug therapy for one or both dogs may be useful but this can only be recommended after professional assessment since there are some situations in which drugs can exacerbate social issues between dogs in the same household.

8.  The process of re-establishing a relationship between two dogs can be difficult to institute correctly and the advice and support of a veterinary behaviourist or a certified clinical animal behaviourist may be advisable. 

Can social aggression between dogs always be corrected?

At times aggression may persist despite owner control and intervention and if the dogs are very closely matched in terms of attributes (sex, age, physical strength, emotional confidence and experience) then the prognosis for reform can be poor. In these cases alternative living arrangements for one of the animals may need to be made. 

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