Summary

We herein present a 51-year-old single female inpatient with treatment-resistant recurrent depressive disorder. Her most recent depressive episode has been severe and followed a chronic course, lasting for longer than 2 years. During the exacerbation of the patient’s suicidal thoughts and plans, we repeatedly and independently observed vegetative and behavioural changes of the therapy-accompanying dog of the patient. Our findings suggest a role for dog-assisted therapy for augmenting treatment as well as for enhancing and developing novel adjunctive strategies for risk assessment in patients with chronic depression and suicidality. Possible social–biological mechanisms and underpinnings are discussed, by drawing on the available literature and comparative psychology. Collaboration with animal behaviourists and animal welfare scientists, in order to improve behavioural and physiological data interpretation and humaneness of dog-assisted therapy, is emphasised as a crucial component of future research.