Physical activity and heart rate in PTSD inpatients: Moderation by custody of a service dog

Posttraumatic stress disorder is associated with autonomic hyperarousal often shown to involve elevated resting heart rate and, simultaneously if somewhat paradoxically, reduced physical activity. Both are risk factors for cardiovascular disease and so may contribute to its elevated prevalence in persons with this diagnosis. Epidemiological studies have observed dog owners to exhibit lower rates of cardiovascular disease. Non-randomized between-group studies have found service dog companionship to be associated with increased physical activity and with lower resting heart rate. A challenge to research in this area is its vulnerability to selection biases in group assignment which could lead to over-estimation of advantages or disadvantages associated with pet or service dog contact and companionship. The current study executed a within-subjects design investigating physical activity and heart rate in a sample of U.S. military Veterans engaged in residential treatment for PTSD and a concurrent service animal training intervention. A mean of 37 days of continuously-recorded day-time physical activity and heart rate were obtained from 45 participants. On days when they had custody of a familiar service-dog-in-training, participants exhibited increased physical activity accompanied by a small reduction in concurrent, activity-adjusted heart rate. Though observed in a specialized context, these short-term findings align with prior observations of lowered risk of cardiovascular disease in association with pet dog ownership. Extended longitudinal designs will be necessary to determine whether such short-term effects truly mediate lowered long-term risk.