© 2016 The Author(s). Background: Many people live with dogs but not all walk with them regularly. This study examines the demographic and behavioural factors that contribute towards owners reporting having a strong sense of encouragement and motivation to walk provided by their dogs, which we call 'the Lassie effect'. Methods: Data was collected from 629 dog owners participating in the RESIDE cross-sectional survey in Perth, Western Australia. Multivariable logistic regression analyses of factors associated with two separate outcome survey items 'Dog encouragement to walk' (how often dog encouraged me to go walking in last month) and 'Dog motivation to walk' (Having a dog makes me walk more). Results: Owning a larger dog; having an increased level of attachment to dog; knowing dog enjoys going for a walk; believing walking keeps dog healthy; and having high social support from family to go walking, were positively associated with both outcomes 'dog encouragement to walk' and 'dog motivation to walk'. Conversely, reporting the presence of children at home; that the child is the main person who walks with the dog; and perceiving dog-specific barriers to walking with dog daily; were negatively associated with both outcomes. In addition, 'Dog motivation to walk' only was positively associated with a belief walking reduces barking, and negatively with owning a dog that is overweight or a dog that is too old/sick. Reporting that the spouse/partner is main person who walks with the dog was also negatively associated with 'dog motivation to walk', as was increased perceived access to public open spaces with dog-supportive features. Conclusions: There are both dog and owner factors that are associated with an owner's sense of encouragement, and motivation to walk the dog, which in turn has been found to be associated with dog waking behaviour. These factors may be targeted in future interventions to increase and maintain physical activity levels of both people and pets.