In the course of a DoD-funded study (Can a Canine Companion Modify Cardiac Autonomic Reactivity and Tone in PTSD) our laboratory has found that the presence of a service canine in the testing chamber in close proximity to the participant is associated with modification of visual attentional bias away from angry faces signalling social threat along with attenuation of autonomic responses to loud tones. The attenuation of bias towards social threat is of particular relevance to the social impairments seen in this disorder.Veterans with chronic severe PTSD frequently manifest impairments in the execution of key social roles such as those of spouse, parent and employee.