The Factors Involved in Dogs’ Fear of Strangers and Unfamiliar Dogs

Less socialization, less exercise, fewer activities with the owner, less training, and breed differences are all linked to social fear in dogs, survey shows.

Dogs' fear of strangers. Pembroke Welsh Corgi (pictured) was least likely to be afraid of strangers
The Pembroke Welsh Corgi was one of the breeds least likely to be fearful of strangers. Photo: Vellicos/Shutterstock

By Zazie Todd, PhD

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Large numbers of pet dogs are affected by fear and anxiety. 72.5% of pet dogs have at least one form of canine anxiety, according to a survey of over 13,000 Finnish dog owners, with sound sensitivity the most common type. Research by Dr. Jenni Puurunen et al (University of Helsinki), published in Scientific Reports, looks at a subset of these dogs to find out the possible causes of social fears (i.e. fear of unknown people and fear of unfamiliar dogs).

6,000 pet dogs were included in the analysis of fear of strangers and/or a fear of dogs they did not know. The results show some expected places where dog owners can do better, and a few more unexpected findings too. 

The biggest factor in both fear of strangers and fear of unknown dogs was inadequate socialization during the time from 7 until 16 weeks. This is the sensitive period for socialization when puppies are learning all about the world they will grow up to live in, and having many different positive experiences is beneficial. But while this result may not come as a surprise to dog professionals, it is still important to get this message out to dog owners. Other research suggests around a third of puppies do not get adequate socialization.  

Most of the dogs were re-homed at 7-8 weeks, but puppies that were weaned later (8 weeks) were more likely to be afraid of strangers. It is not known if they went to their new home later because they were already fearful, or if going later to their home meant they had less socialization.

Of course, to some extent fear is also genetic and so it is not surprising the study found some breed differences. In particular, the breeds that were least fearful of other dogs were the Pembroke Welsh Corgi, Cairn Terrier, and Wheaten Terrier, while the breeds most fearful of dogs were the Chihuahua, Shetland Sheepdog, and Spanish Water Dog. 

Being afraid of dogs often correlated with fear of strangers, but not always, as for example the Chihuahua was not rated as afraid of strangers (but the Shetland Sheepdog and Spanish Water Dog were). The Chinese Crested Dog was also more likely to be afraid of strangers, while the three breeds least likely to be afraid of strangers were the Wheaten Terrier, Finnish Lapponian Dog, and Labrador Retriever. (Incidentally, the Cairn Terrier and Labrador Retriever both feature on my list of good alternatives to the French Bulldog).

Some breeds are less likely to be fearful, including the Pembroke Welsh Corgi (pictured)
Photo: Vellicos/Shutterstock

Fear of other dogs was less likely in dogs over 6 years old. Small dogs were more likely to have social fears than large dogs. Female dogs and dogs that had been spayed/neutered were also more likely to be fearful of strangers and unfamiliar dogs. It is not known if this is due to hormones affecting behaviour, or other factors such as fearful dogs being more likely to be neutered as they are less likely to be used for breeding. Spay/neuter practices in Finland are quite different than those in the USA and Canada, where a much higher proportion of dogs are sterilized. 

Perhaps surprisingly, living in an urban environment was also associated with increased social fears. The reason is not known and could reflect differences in how pets are kept in these environments, the numbers of other dogs and people they meet (and perhaps a lack of choice in meeting them in crowded spaces), or other factors.

Not getting as much exercise was correlated with fear of unfamiliar dogs. Both types of fear were more common in dogs who took part in fewer joint activities with their owner and fewer training sessions. Again it is hard to be sure why without further research, as fearful dogs may not be taken out and about as much by their owners. But it is also possible that exercise and activities with the owner reduce fear, improve the bond with the owner (helping them to be a ‘safe haven’), and/or give the dog better coping skills for stressful situations.  

The scientists write,
“In this survey study, we demonstrate that socialisation during puppyhood is strongly associated with social fearfulness in dogs, consistent with previous research. We have also replicated other findings from previous studies, as we show that fearful dogs are more often small, females and neutered, and participate less often in training and exercising. In addition, we identified several breed differences, suggesting that some breeds may be more vulnerable to develop social fear-related problems than others. Moreover, we report a novel association between the living environment of the dog and social fearfulness that requires further research.”

This study has a large sample size, and steps were taken to control for the number of statistical tests that were done (which otherwise might have led to false positives). It has to remembered that these results are correlational and do not prove causation. Nonetheless they tie in with other research, and the findings are especially important given the number of dogs affected by these fears. The paper is open access (link below).

Because it can sometimes be hard for dog owners to recognize signs of fear, you might like my post on how to tell if your dog is afraid. Other posts that might be especially useful are eight tips to help fearful dogs feel safe, and desensitization and counter-conditioning

If your dog is afraid of loud noises, speak to your vet in case pain is a contributing factor and/or medication is recommended for the fear.  And be aware that in addition to doing desensitization and counter-conditioning, ad-hoc counter-conditioning (when noises happen to occur) seems to help with fear of loud noises.  

If you liked this post, check out my book Wag: The Science of Making Your Dog Happy. Modern Dog magazine calls it "The must-have guide to improving your dog's life."

Is your dog afraid of people or dogs they don’t know?  

Zazie Todd, PhD, is the award-winning author of Wag: The Science of Making Your Dog Happy and Purr: The Science of Making Your Cat Happy. She is the creator of the popular blog, Companion Animal Psychology, writes The Pawsitive Post premium newsletter, and also has a column at Psychology Today. Todd lives in Maple Ridge, BC, with her husband, one dog, and two cats. 

Useful links:

Puurunen, J., Hakanen, E., Salonen, M. K., Mikkola, S., Sulkama, S., Araujo, C., & Lohi, H. (2020). Inadequate socialisation, inactivity, and urban living environment are associated with social fearfulness in pet dogs. Scientific Reports, 10(1), 1-10. 

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