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Understanding Fear and Stranger-Directed Aggression in Companion Dogs

By Hannah Flint

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Stranger-directed aggression is both a public safety and animal welfare concern. The objectives of this thesis were to identify risk factors for stranger-directed aggression in dogs, to assess the effect of targeted owner training on the accuracy of ratings of fear in dogs, and to identify behaviours associated with fear in puppies. Risk factors for stranger-directed aggression were first analyzed using an existing dataset of responses to the Canine Behaviour Assessment and Research Questionnaire (C-BARQ). Fear of strangers, non-social fear, sex and neuter status, age at evaluation, age acquired, where acquired, and breed group were significantly associated with stranger-directed aggression. There was also correlation in this behaviour among dogs from the same participant and country (n=14,310 dogs; 10,951 participants; 67 countries). To further explore the similarities from dogs with the same owner, a survey including the C-BARQ, as well as additional questions relating to dog characteristics, temperament, training, environment and owner demographics and personality was distributed. Dogs’ stranger-directed aggression scores were significantly associated with fear of strangers, impulsivity, sex, reason for neutering, training methods, history of abuse, quantity and quality of socialization as a puppy, where kept when left alone, how exercised, breed group, owner extroversion, and whether owners could accurately identify the absence of aggression from videos (n=2,760 dogs; 2,255 households). As fear was found to be associated with stranger-directed aggression, it is important that owners are able to accurately recognize it in dogs. Using a targeted training tool, based on fear behaviours owners were able to reliably identify, recognition of mild to severe fear in videos of dogs improved, but owner ratings of their own dogs’ fearfulness were not consistently altered. Finally, to identify fear behaviours shown by puppies, an approach/avoidance test was developed and used to categorize puppies’ responses to fear-provoking stimuli. Lowered posture, lowered tail, freezing, flinching, retreating, barking, and paw lifting were found to increase with non-social fear in puppies. These results can help with identification of dogs at risk of developing stranger-directed aggression, and can direct owners to appropriate training and prevention strategies.


Marcy Wilhelm-South

Purdue University

Date 2017
Pages 311
Department Department of Population Medicine
Degree Doctor of Philosophy
Language English
University University of Guelph
Cite this work

Researchers should cite this work as follows:

  1. Aggression
  2. Animal roles
  3. Animal welfare
  4. Dogs
  5. Fear
  6. Mammals
  7. open access
  8. Pets and companion animals
  9. Stranger Reactions
  10. young animals
  1. open access