Understanding Dogs That Fight
World Small Animal Veterinary Association World Congress Proceedings, 2011
Karen L. Overall, MA, VMD, PhD, DACVB, ABS, Certified Applied Animal Behaviorist
Philadelphia, PA, USA

To understand and help dogs that fight it is necessary to both understand their signaling in a larger context of overall pathological behavior, and how to utilize these signals to distinguish when animals are communicating and interacting normally from abnormally. Nowhere is this more important than for aggression between dogs because there is an almost uniform belief that some aggression can be 'normal' in dog-dog interactions. The inherent problem is whether the aggression label is misapplied to normal, tussling social behaviors.

These goals are impossible to accomplish if we cleave to an outdated, unfortunate, and unsubstantiated terminology: that of the 'alpha' or 'dominant' dog. The modern and evolving understanding of complex social behaviors is going to require that we relinquish simplistic and damaging labels: the concept of a 'dominant' dog is not useful in these situations, and asking clients and practitioners to identify and support the 'dominant' dog can cause not just further morbidity, but mortality. An unpublished study of dozens of cases involving interdog aggression between household dogs found that most clients had been advised to support or reinforce the 'dominant' dog, and that when they did so, the aggression worsened.1 One could argue that the clients are not correctly identifying the 'dominant' dog, but if a label is causing such difficulty, it may be time to stop using it. The issues of 'dominance' and social rank on group interactions comprise one of the oldest, most confusing, and hotly debated areas in the behavioral literature. It's important that we understand why this concept has caused problems in the practice of veterinary behavioral medicine.

The existence of a hierarchy has been postulated to be a stress-reducing device2; however, situations where hierarchies are most rigidly maintained are also ones where measures of stress are high3. 'Dominance' has been traditionally defined as individual's ability, generally under controlled situations, to maintain or regulate access to some resource.4-7 Given that the definition of 'dominance' can be further refined as a description of winning or losing staged contests over resources8, and that a winning outcome needn't confer priority of access to those resources8, we must accept that variable distributions of resources (e.g., access to attention, beds, resting sites, toys, food dishes, et cetera) will lead to variable hierarchal classifications.

We have been encouraged to treat dogs inhumanely under the guise of being 'dominant' to them. This has likely resulted in the injury or death of many dogs because we have reinforced a truly pathological animal as 'dominant'. These concerns are not new: the potential to mislead was Rowell's primary concern when she published her ground-breaking study on the intricacies of baboon social interactions.9 When free-ranging baboon interactions were classified by behavioral types (e.g., friendly, approach-retreat), and then analyzed according to specific behaviors of the participants, no 'dominance' system was noted. A much more complex, elegant system of interactions that reflected relatedness, age, sex, social history, et cetera became apparent. The online position statements by groups devoted to humane behavioral care for pet dogs now concur (http://www.avsabonline.org/avsabonline/images/stories/Position_Statements/dominance%20statement.pdf, http://www.dogwelfarecampaign.org, http://www.dogwelfarecampaign.org/why-not-dominance.php).

Most social behaviors, when fully examined, are not characterized by agonistic encounters, but by fluid, context-specific deferential behaviors.10 Deference is not analogous to submission or subordination. Deference is about relative status that is freely given, not imposed. The animal to which most others defer is the animal that behaves most appropriately given the context, not the animal who must always be at the door first, or must eat first. In fact, a need to control regardless of context can be neither adaptive, nor normal. The role for deferential behaviors is suggested by authors who have looked extensively at social interactions when they discuss the variability in the behavior of high ranking animals.

Instead, consider asking clients to do 1 simple thing: correctly identify the animal in the interaction who is behaving most appropriately and protect and reinforce this animal. If clients and veterinarians can watch videos of the dogs interacting in low-to-no risk circumstances, even without knowing what to call the behaviors, they will see differences. This is the first step in learning to better read feline and canine signaling, and will help clients to identify the specific behaviors and signals of concern.

Interactions are not an event - they are a process. A fight is a snap-shot viewed without the reference frame of the long movie that is the animals' lives together. In the absence of repeated snapshots, videos, or some other evaluation of social interaction over time, we can learn about variability in response and when it changes to abnormal by viewing a series of videos of dogs interacting with different outcomes.

Clients need to know that their dogs will learn from their interactions with each other, and both 'combatants' may hone their aggressive skills. Attackers may become faster, and signal their intent less intensely with time, and victims may learn that they can minimize damage to themselves if they exhibit a pre-emptive attack. In such circumstances, it is easy to err in identifying the aggressor vs. the victim. The key is to be able to identify when the behaviors are about learning normal social roles in changing social environments, and when they are about truly pathological behavior. Because learning works by altering neurochemistry11, clients should understand that both early intervention designed to avert anxiety associated with underlying aggression and pharmacological intervention can help, but neither approach will be used appropriately until the clients can understand the signaling and interactions from the dogs' viewpoints12.

Guidelines for clients to help dogs that fight13:

1.  Keep all dogs involved in the interdog aggression separated at all times when not supervised. Keeping dogs separate within a household is difficult and requires thought, tangible plans, and possibly a written map or floor plan. If the aggressor can be identified that dog should be confined to the less desirable room (a spare bedroom, a pen in the heated, well-lit basement or garage). All other dogs should have free-range. If more than one dog is actively problematic, all the problem dogs should be confined, and the non-problem dogs can be left loose. If everyone is a problem, all dogs should all be kept in crates/rooms where they cannot see each other or threaten each other.

2.  Bell the dogs with different sounding bells that you can distinguish. If you cannot distinguish the sounds, bell only the aggressor. The bell will tell you when the aggressor is approaching and when the problem dogs are close together. The dogs who have been victimized by the aggressor can also use the bell to monitor his or her movements and avoid interaction. Dogs who are having problems with each other can have a chance to approach each other if and only if you are confident that you can control them long-distance, and prevent any injury. Please remember - injury can be physical or behavioral. Of these, the behavioral injury may be worse for many dogs who learn to live in constant terror. If you do not feel that you can adequately monitor the dogs when loose, or that you cannot read the dogs' signals well enough to relax, that's fine. You now have 3 choices: a) one or both dogs are crated, b) one dog is behind a baby gate, or c) the dogs are each on harnesses or head collars and restrained so that they cannot get to each other.
Again, please remember that dogs who are separated but who are staring at each other are not 'mentally' separated. The dog who is being threatened can be trapped by crates, gates, and leads. Do not let this happen. These dogs can only be together under the conditions listed above if neither one of them visually or physically threatens the other. Also, if a dog is afraid of crates or cannot exhibit normal behaviors when in them, please do not crate that dog. Feeling entrapped makes such dogs more anxious and reactive and will worsen your situation.

3.  Choose an order in which to reinforce the dogs based on identifying which dog is behaving the most appropriately. Remember - reinforcement is not about rewarding the pushiest, most 'dominant' dog. It's about rewarding the dog who is most appropriate so that all the dogs get the message that obnoxious/abnormal behaviors are not rewarded, but calm, non-threatening ones are. This type of reward-based reinforcement works because it mimics canine social systems and uses deferential behaviors to get attention and other 'currencies'. When you reinforce the most appropriate dog you feed that dog first, give him or her attention first, give them access to the yard first, et cetera. Remember, it is abnormal to respond to a deferential behavior with a threat. By definition, aggression that occurs when the recipient is signaling that they are not a threat is inappropriate and out-of-context. Do not assume that these dogs will not injure each other. These dogs can seriously disable or kill each other in such circumstances. If the dog that is deferring cannot hold the 'status' in a way that encourages the aggressive dog to back down - and she may be doing everything right - you will either have to keep the dogs continuously separated or find one of the dogs another home. If you decide to place the challenger, that dog can only go to a home where he or she will be the single dog.

4.  Reinforcing the chosen dog has active and passive components. First, separate them as discussed above. Second, enforce the concept that the dog being threatened has the right to exist by feeding him first, letting him out before the other dog(s), giving him a treat or toy first, walking first, playing with first, grooming first, et cetera. Make sure you understand what is really being said here......this is not about 'dominance'. It's actually about providing a clear set of rules that provide information about which dog should serve as the model for the other dogs' behaviors. You are encouraging the normal types of social deference that would be exhibited by dogs under normal conditions. By reinforcing an appropriately behaved dog you encourage the normal fluidity of the social system and can then reward the aggressive dog for not reacting.

5.  Fit all dogs with a head collar, or a good no-pull harness, and gradually reintroduce them to each other when there is no attention being given. Make sure that you have followed good behavior modification protocols that allow for desensitization.10,13

In this world view, treatment is about both understanding the neurochemical changes that occur with learning and repeated exposure, and about becoming more humane. To do this, we must begin to see the world from the dog's point of view, which minimally requires that we let go of labels which may say more about us and our need, than they do about the behavior. The situation with interdog aggression demonstrates why we need to be more mindful of terminology, issues, and approaches which can inadvertently do more harm than good.

Anti-anxiety medications may help some dogs that otherwise are not able to succeed, and are routinely required for serious aggression. Please remember, if it's decided that medication could benefit your dog, you need to use it in addition to the behavior modification, not instead of it.


1.  Overall KL, Dunham AE. Unpublished 2004.

2.  Collias NE. Social behaviour in animals. Ecology 1953;34:810–811.

3.  Rowell TE. Hierarchy in the organization of a captive baboon group. Anim Behav 1966;14:430–443.

4.  Hinde RA. The nature of aggression. New Society 1967;9:302–304.

5.  Hinde RA. Animal Behaviour. 2nd edition. New, York, McGraw-Hill, 1970.

6.  Landau HG. On dominance relations and the structure of animal societies. I. Effects of inherent characteristics. B Math Biophysics 1951;13:1–19.

7.  Rowell TE. The concept of social dominance. Behav Biol 1974;11:131–154.

8.  Archer J. The Behavioural Biology of Aggression. Cambridge, Cambridge University Press, 1988.

9.  Rowell TE. A quantitative comparison of the behaviour of a wild and a caged baboon group. Anim Behav 1967;15:499–509.

10. Overall KL. Clinical Behavioral Medicine for Small Animals. St. Louis, Mosby, 1997.

11. Overall KL. Pharmacological treatment in behavioral medicine: the importance of neurochemistry, molecular biology, and mechanistic hypotheses. Vet J 2001;62:9–23.

12. Rooney NJ, Bradshaw JWS, Robinson IH. Do dogs respond to play signals given by humans? Anim Behav 2001;61:715–722.

13. Overall KL. Manual of Clinical Small Animal Behavioral Medicine. St. Louis, Elsevier, 2011.


Speaker Information
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Karen L. Overall, MA, VMD, PhD, DACVB, ABS Certified
Applied Animal Behaviorist
Philadelphia, PA, USA

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