• Amy Cameron

Getting to Grips With Intermittent Canine Aggression

Dog aggression is a complex subject that requires a deep understanding of dog behaviour and an ability to observe the dog and it's environment. Aggression can be caused by multiple factors and carefully managed training plans are often required to address these factors.

Aggressive Behaviour in Dogs

Often assumptions are made about dogs who bark, lunge, bare their teeth and snap at other dogs, people or objects. People see these behaviours and believe that the dog is nasty or out of control and even you as their owner may feel the same. This may be true in some cases, but generally these behaviours can arise because of other factors, namely fear, anxiety or over-stimulation, with the dog either being overwhelmed by a situation and not knowing how to respond or due to them being overexcited.

In many cases, dogs will show subtle signs of unease in situations, which can escalate into severe signs of aggression if missed or ignored. This is why sudden barking and snapping may seem out of the blue and the assumption that the dog is aggressive. Most dogs, particularly those who have had appropriate socialisation with other well-socialised dogs will follow a ladder of aggression, initially displaying subtle behaviours of apprehension in attempts to diffuse a situation before moving up and being more clear about their unease. For dogs who have not had appropriate socialisation, or their subtle behaviours have been ignored, they may learn to skip out the early indicators and just go straight to what works, biting.

Aggression Escalation (Canine Principles, 2017 )

Intermittent Aggression

Intermittent aggression refers to aggressive behaviours that are unforeseen or to aggression that does not always occur in a situation that has previously caused aggressive reactions from the dog. This can cause a lot of confusion and uncertainty in owners as they are unable to judge when their dog is going to 'snap'. However, in most cases the dog's severe reactions will have been preceded by subtle behaviours indicating that they are uncomfortable and in the majority of situations something will have caused the reaction.

It is very unlikely that a display of aggression has occurred for no reason and in the majority of cases. Although not always obvious, there is usually a specific trigger that has caused the dog to react negatively, or a connection can be made between separate displays of aggression. Taking time to consider the situations when aggression occurs can help you identify a pattern, for example you may find that your dog is only aggressive when:

  • you walk them, but they are OK when your partner walks them

  • they are on a lead

  • in certain environments, e.g. they are aggressive towards other dogs when walking down the street but they are OK with dogs at daycare

  • they meet certain breeds, colours, genders or sizes of dogs

  • they get back from a walk

Given human nature and the busy world we live in, it is not possible to observe our dog's every behaviour. Therefore, it is understandable that we may not notice the subtle behaviours that our dogs display or to not recognize a connection between every sudden outburst.

Why Dogs React Differently in Similar Situations

There are various reasons why dogs may only display aggressive behaviours in certain situations or environments and it can be due to several factors.


Pain in dogs, particularly chronic pain, can often go unnoticed and is not always considered when a dog develops aggressive behaviours. However, this should always be the first thought if a dog has snapped, lunged or bitten. Most commonly associated with contact being made with the dog, pain can also cause a dog to become apprehensive about other dogs or people approaching and will display 'aggressive' warning behaviours in advance.

Fear & Anxiety

Negative experiences can lead to fear and anxiety, which can cause a dog to become aggressive when in the same situation or if they are exposed to the object that caused fear. Similarly, lack of experience in a certain scenario can cause aggressive behaviours because the dog is unsure how to react appropriately or deal with the stimuli.


When a dog has a negative experience that causes fear or trauma, it is easy to understand that the scary thing can cause fear and fear-based aggression when they experience it again. However, sometimes a dog can generalise the experience and associate other objects, individuals or the type of environment with the fear they experienced, thus making them fearful of those stimuli too.

Trigger Stacking

Some dogs can cope or hide their anxiety, but over time, each little fear inducing event that doesn't cause an outward reaction is building up. Eventually, without time and space to calm down, the dog will snap. Trigger stacking makes it clear why identifying a specific cause for a dog's aggressive behaviour can be difficult. For example, it may seem that a dog doesn't like small dogs, until one day it reacts to a big dog. It could be that the dog is uncomfortable with all dogs, but coincidentally they originally only 'snapped' when small dogs went by.


As with humans, play can often get out of hand and be taken too far. It may be that a dog starts to show aggressive behaviours when they get worked up during rough-play and consequently become frustrated. Or it may be that the other dog is over-excited and is becoming too much too quickly and the dog on the receiving end of the rough play has had enough and the only way they can communicate that to the other dog is by being very clear and assertive.

Emotional State of Others

It is possible that your own, or another person's behaviours and feelings may cause your dog to be more reactive in certain situations. Dogs are able to pick up on tension and if we feel uneasy in a situation, our dogs will feel it, which can cause them to feel anxious or may lead to them feeling overprotective of you. Similarly, dogs can pick up on other dog's emotional states and indicators that may put your dog on the offensive. It could also be (as with humans) that your dog just does not like the other dog and there is no obvious reason why, which is OK... they don't have to like every dog they meet.

What Can You Do About It?

Firstly, trying to remain focused on your dog is essential to managing a situation and preventing a display of aggression. It can also be helpful to work out what is triggering your dog's behaviour. Writing everything down associated with the display of aggression, such as time of day, weather, your emotional state before the event, how your dog was before the event, the environment in which it occurred and a detailed description of what your dog was being aggressive towards. For example, if it was a dog or person, what did they look like or what were they doing. If the dog reacted to something other than a living being, what sounds were occurring, what was in the environment or what was the targeted object doing. From this information, you or a professional could start to piece together the whys of the behaviour, giving you direction and focus for training and management.

Once you know what is causing the aggression, preventing your dog from becoming overwhelmed and avoiding putting your dog in uncomfortable situations is vital until they learn appropriate coping skills. This can be achieved in a variety of ways, but will depend on your dog's individual situation. You will mainly need to focus on building your dog's confidence and coping skills through positive training and a behavioural modification programme that involves desensitisation and/or counter-conditioning.

Having a second pair of eyes can be helpful to understand and solve aggression problems. Finding a good behaviourist who is willing to work with you and your dog in a positive manner can be the most efficient way of dealing with any behavioural problems. However, you must remember that you will have to do the majority of the hard work and need to be willing to put in the effort everyday if you want to achieve results.

Over to You...

Your dog's aggression can be managed, but it's up to you to start the process. Knowing that aggression is not simply an act of being mean or 'dominant' and is something more unpleasant; fear, anxiety, pain etc is reason enough to work with your dog to help them feel safe and happy. It will also benefit you in the long run and enable you to enjoy your relationship with your dog more.