The Four F’s are a reflex, immediate, subconscious behavioural response to stress. There is no input from the higher centres of the brain in these responses, they are automatically triggered and can occur within 0.03 sec of a dog’s amygdala being activated.
Dogs are highly social animals, and so have developed an intricate body language as a means of communication between individuals. This body language reflects a dog’s underlying emotions and motivations in a situation. It is extremely important for both us and other dogs to observe, reflect, understand and react appropriately to a dog’s emotional signals in order not to cause further distress to the dog.
The Four F’s can help us to identify when dogs are in the RED or ORANGE zones and are feeling fearful, threatened, scared, aroused or distressed by a situation. Absence of the Four F’s may indicate that a dog is in the GREEN zone.

Fiddle

These behaviours are displacement behaviours, or behaviours which are normal, but inappropriate or out of context of the situations. Human equivalents are laughing at a funeral, twiddling your hair or thumbs or tapping your leg when you are impatient/disagree.
These ‘fiddle’ signs are often one of the earliest signs of disomfort. Different dogs may ‘fiddle’ differently.

−Panting when not hot or overweight
−Yawning when not tired
−Lip licking when no food is present/not hungry
−Shaking off when coat is not wet
−Mounting (animals, people or objects) when desexed
−Hypervigilance; constantly scanning the room
−Scratching when not itchy
−Checking their ano-genital region when they haven’t recently toileted
−Penile crowning/Erection when desexed

Freeze

This is the dog equivalent of ‘playing dead’. Via evolution, ‘freezing’ by standing very still may have been a way of indicating that a dog was not threatening, or helped it to hide from a predator. Some dogs express the freeze response by walking very slowly, as if they are in slow motion or swimming through jelly.

Flight

Many dogs will flee from a situation if given the opportunity. This may involve moving away, or hiding. Subtle signs can include moving away from a person/object/stimulus the dog finds threatening, or moving towards something which makes a dog feel safe, eg their family or a crate.

Fight

−Barking
−Hackles
−Growling
−Lip lifting
−Snarling
−Snapping
−Biting

Aggression is a common expression of fear. The Fight response is just another expression of distress. A dog who is running away (flight response) and a dog who is trying to bite (fight response) are feeling the same level of fear emotionally.
Many dogs will only ‘Fight’ if all other ‘F’s’ have been demonstrated and have not been successful in alleviating their fear. However, with repeated incidences, some dogs learn that ‘Fight’ is the most effective means of distancing danger, and so their immediate response to a stress or a threat, is a ‘fight’ response.

If you notice your dog showing any of the Four F’s, it is vitally important to remember and understand that they are feeling stressed, scared, fearful or uncomfortable and to try to help them to feel better. Often the easiest way of doing so is by removing them from the situation.