Addicted to playing? Establishing an addictive-like behavioural phenotype in pet dogs

Behavioural addictions, characterised by compulsive engagement in rewarding activities despite adverse consequences in the long term, are more heterogeneous and less well-understood than substance addictions, and there is a relative lack of translational research. This study investigates "excessive toy motivation" in domestic dogs as a potential parallel to behavioural addictions in humans. Employing a combination of a behavioural test and an owner questionnaire, we examined whether a subset of highly play-motived dogs meet key behavioural addiction criteria including craving, salience, lack of self-control, and mood modification. Data from 105 highly play-motivated dogs revealed that 33 subjects exhibited behaviours consistent with addictive-like tendencies, including an excessive fixation on toys, reduced responsiveness to alternative stimuli, and persistent efforts to access toys. Owner-reported behaviours not only corroborated these findings but also demonstrated significant associations with behavioural test scores. Our results highlight parallels between excessive toy motivation in dogs and human behavioural addictions, with dogs as the only non-human species so far that appears to develop addictive-like behaviours "naturally" without artificial induction. This exploratory study provides foundational insights and proposes future research directions that have the potential to significantly deepen our understanding of the psychological mechanisms underlying behavioural addictions across species.