Animal Behavior & Training

Aggressive Behaviour in Dogs

Aggressive behaviour is common in dogs and, while it should never be taken lightly, there is always a reason for it. Just because a dog is aggressive in a certain situation, it does not mean he is an "aggressive dog".

Dr James O’Heare defines aggression as an adaptive behaviour which is meant to help them get things they want (or perceive as safe) and to avoid or escape from things they do not want (or perceive as dangerous) (1). Dogs often use a number of strategies to communicate the fact that they are feel under threat or extremely uncomfortable with a situation and will usually give one or a number of signals to indicate their discomfort. If the signals are repeatedly ignored, a dog may resort to snapping or biting as a final strategy to remove the threat.

The signals to watch out for include (bear in mind these do not necessarily occur individually and can occur in a matter of seconds!):

(i) Snarling

The dog wrinkles its nose and pulls its lips back to reveal its teeth, providing a visual signal that it has a set of potentially lethal weaponry and may be prepared to use it if the provocation continues. This may be accompanied by staring eyes (but not at the source of the threat) and repeated 'mini-freezes'. At this stage, although this is an aggressive display, it is designed to avoid further conflict and/or risk of injury. Sometimes the dog may turn its head away as if trying to conceal its weaponry (a possible sign that it would rather not use it or a deliberate concealment to ensure an element of surprise if and when the dog attacks) even though it is simultaneously displaying it.

(ii) Freezing

A dog may turn its head away from the source of provocation, breaking eye contact, to indicate that he/she is not a threat. The dog ‘freezes’ at the same time. Freezing is one of four common responses (the others being fight, flight or fiddle about/appeasement gesture) that a dog may employ when faced with a perceived threat or challenge. A dog may repeatedly use the mini-freeze as a strategy to try to escape/avoid the provocation, as well as to obtain more information about the threat and plan the escape and/or to calm itself down (displacement activity). The mini-freezes may get more intense as the provocation continues, in the sense that they last longer, but eventually, if the strategy fails (i.e. is ignored) the dog may snap or bite. In such a case, passive defensive behaviour has failed and the dog has progressed to fight, an active defensive behaviour.

(iii) Growling

This is a deep, threatening sound (may be quiet or loud) used to warn another person or animal that the dog wants them to stop whatever behaviour they are engaging at that moment and/or remove themselves from the situation (2). In other words, the dog is communicating the fact (via an auditory signal) that it has had enough and, if the warning goes unheeded and provocation continues, the aggressive behaviour can be expected to escalate to the next level.

(iv) Staring/rolling eyes

A direct stare is interpreted as hostile behaviour in dogs. A dog may also stare into space during a 'mini-freeze', and not at the source of his discomfort. In this case, a dog may be looking at a possible escape route, or is simply trying to escape the perceived threat by breaking eye contact. The dog may also show the white of its eyes (‘whale-eye’) which is common in food guarding and, often the pupils are widely dilated, a physiological response to stress.

(v) Ears back

If a dog pins its ears backwards, it is usually an indication of fear or anxiety. This is another indication that the dog may resort to aggression if it feels cornered. 

Mostly, the above signals are not given individually, but combined with one or more other signals as the dog tries to find a way of coping with the impending threat. But if they are routinely ignored, the dog moves to the next level of aggression until it feels compelled to bite.

In situations such as these where aggression is an obvious possibility, humans can help themselves by reading the signals and responding to them. So, they should not stare directly at the dog which may be perceived as hostile/threatening, but instead make soft eye contact (i.e. briefly meeting the dog’s gaze and then looking away again) and also looking at the dog from a sideways standpoint, rather than facing it head on. Slowly retreating from the food bowl and crouching/stooping so that one does not appear so imposing (but ensuring that the dog can be kept at sufficient distance to ensure the face/body does not get bitten) may help reduce the challenge in the dog’s eyes, but care must be taken not to leap away precisely as the dog snarls or growls. If this happens, it runs the risk of teaching the dog that growling and snarling gets him what he wants and such a successful strategy will very quickly become a learned behaviour. Bending forward in the dog’s space should be avoided as should crowding the dog. At the same time, movements should remain fluid, with the person continuing to talk in a quiet, calm manner to promote relaxation in the dog. All actions should be positive and firm, neither rushed nor dithering. The aim is to give an impression of quiet control rendering any thought of active confrontation futile (3).

See also Canine Body Language, The 'D' Word and Let's Be Friends.


1 – O’Heare, James: The Canine Aggression Workbook 2nd Ed – Dogpsych 2003
2 - Abrantes, Roger: Dog Language, An Encyclopaedia of Canine Behaviour – Wakan Tanka 1997
3 – MacKinnon, Pam: Handle With Care! – Alpha 2004

Copyright © Susan Nilson 2007

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