Students in higher education face a multitude of life changes and challenges. In order to promote their mental health, the use of canine-assisted interventions (CAI) has gained increasing attention, yet one area that remains insufficiently studied is the influencing characteristics that may lead to the positive effects of CAIs. This study is a follow-up study to a previously published study, aiming to investigate qualitatively the factors that may influence the change in well-being during a CAI. In the present study, 27 students participated in a 15-min CAI in which they interacted freely with a dog. Using the Basler Befindlichkeitsskala, their well-being was assessed. Participants reported personal characteristics and evaluated the intervention to identify possible influencing characteristics. Additionally, the intervention process was videotaped and analysed. Results showed greater positive effects on well-being for students who did not own a dog, for whom the intervention was delivered by more experienced dog-human teams, and for whom the intervention was characterised by a high interaction intensity with a high proportion of 'petting the dog' while showing low interaction with the handler. Implications for the use of CAIs are discussed.