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Assessing fear in dogs in response to social and non-social stimuli

Fear is an emotion that is elicited in response to a potential threat or stressor. Experiencing fear places an animal in a negative emotional state, which can impact their welfare and lead to the development of behavioural problems. For instance, studies have found that a fearful dog is more likely to develop aggression, separation anxiety, destructiveness, and inappropriate elimination (Martínez, et al., 2011).

It is therefore very important that dog owners are able to identify fearful behaviours in their dog so that they can then identify the source of the fear and begin to work to reduce the associated fearful behaviours.

Commonplace fearful situations for a dog include, but are not limited to, thunderstorms, vacuum cleaners, meeting strangers, and introduction to new environments. Stimuli that produce fearful responses can typically be broken down into social (e.g., a human or dog) and non-social stimuli (e.g., a toy car or umbrella). These stimuli typically generate a fearful response when they are new to the animal experiencing it and if they have a sudden appearance.

Main Fear Behaviours in Dogs

  • Reduced posture/cowering

  • Freezing

  • Avoidance and escape attempts

Less Obvious / Subtle Fear Behaviours in Dogs

  • Trembling/shaking

  • Yawning

  • Salivating

  • Panting

  • Paw-lifting

  • Vocalizing

  • Piloerection (back hair rising)

  • Autogrooming (grooming itself)

  • Coprophagy (eating feces)

  • Repetitive behaviours (e.g., pacing, circling)

  • Oral behaviour (e.g., lip licking)

  • Intentions to change locomotor activity

  • Nosing

  • Digging

Many studies in the literature have identified dog’s fear responses to various types of force-exposed stimuli (e.g., sound blast, electric shock, opening umbrella) but none have studied dog responses towards everyday stimuli, where a dog has the choice to approach it or not. In particular, it is unknown whether subtle behavioural indicators of fear (see above for a list of these behaviours) are displayed consistently across different types of stimuli and with different levels of fear. The Companion Connection member, Anastasia Stellato, sought to tackle this gap in the literature through her MSc thesis.

In this study, 30 owned dogs were recruited and researchers assessed their responses towards a social stimulus (a suddenly appearing stranger wearing a mask and a cape) and a non-social stimulus (a suddenly appearing garbage bag filled with crumpled newspaper). The dog and its handler were 4.6 m away from the stimuli thereby reducing the intensity level of the stimuli presentation. After the stranger or the bag suddenly appeared the handler encouraged the dog to approach. Fear behaviours were measured when the stimuli was presented and when the dog was encouraged to approach. Dogs were categorized as fearful based on known fear indicators: reduced posture and avoidance behaviour. Also, subtle behaviours – body shaking, hiding, yawning, vocalizing, tail wagging, lip licking, paw-lifting, digging, and nosing – were observed.

Upon stranger appearance, the dog is hesitant to approach and is showing avoidance behaviour.

After the bag drops, the dog is surprised by its arrival and is displaying curiosity to investigate it.

Researchers found that more of the fearful dogs displayed subtle fear-related behaviours than non-fearful dogs only when they were encouraged to approach the stranger. The number of subtle behaviours shown during testing was relatively small. Total subtle behaviours were positively correlated with the intensity of avoidance when the stranger appeared, and when the dog was encouraged to approach the stranger. Total subtle behaviours performed also positively correlated with posture scores when the dog was encouraged to approach both the bag and the stranger.

These findings suggest that when subtle behaviours are performed, they may be related to fear in dogs. However, not all dogs that were scored as fearful showed subtle behaviours. Furthermore, the correlations found were relatively weak, indicating that subtle behaviours are unlikely to be reliable indicators of fear in situations where dogs have control of their approach towards and avoidance of stimuli.

This research highlights the need for owners to pay special attention to every day stimuli that surround their dog that may trigger less obvious signs of fear. Although the dog has the ability to walk away from the fearful object/environment, the dog still may be stressed and action should be taken in order to prevent this fear from becoming worse, especially if the nature of the fear-eliciting stimuli changes.

This research has since been published and is available at the following link:


Beerda, B., Schilder, M.B.H., Van Hooff, J.A.R.A.M., De Vries, H.W., Mol, J.A. 1998. Behavioural, Saliva Cortisol And Heart Rate Responses To Different Types Of Stimuli In Dogs. Applied Animal Behaviour Science, 58: 365-381.

Beerda, B., Schilder, M.B.H., Bernadina, W., Van Hooff, J.A.R.A.M., De Vries, H.W., Mol, J.A. 1999. Chronic Stress In Dogs Subjected To Social And Spatial Restriction. I. Behavioural Responses. Physiology & Behaviour, 66(2): 233-242. 

Beerda, B., Schilder, M.B.H., Van Hooff, J.A.R.A.M., De Vries, H.W., Mol, J.A. 2000. Behavioural And Hormonal Indicators Of Enduring Environmental Stress In Dogs. Animal Welfare, 9: 49-62. 

Martínez, A.G., Pernas, G.S., Casalta, F.J.D., Suárez Rey M.L., Cruz Palomino, L.F.D.L., 2011. Risk Factors Associated With Behavioral Problems In Dogs. Journal Of Veterinary Behavior, 6: 225-231.

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