Characterizing veteran and PTSD service dog teams: Exploring potential mechanisms of symptom change and canine predictors of efficacy.

Psychiatric service dogs are an emerging complementary intervention for posttraumatic stress disorder (PTSD). Initial evidence suggests that partnership with a service dog may be related to less PTSD symptom severity. However, it remains unclear how or why this might occur. To address this gap, we conducted a longitudinal investigation of 82 post-9/11 military members or veterans and their PTSD service dogs to (1) evaluate service dog characteristics as potential predictors of efficacy, (2) assess dog and human characteristics as potential predictors of veteran-dog bond, and (3) explore potential mechanisms for mental health outcomes. Aim 1 results demonstrated that most service dog characteristics did not predict veterans' mental health outcomes, but lower service dog excitability was associated with less PTSD symptom severity at follow-up. Aim 2 results showed that closer dog-veteran relationships were associated with less excitable dog temperament. Aim 3 results indicated that worse mental health at follow-up was associated with greater use of the specifically trained PTSD service dog task to initiate a social greeting ("make a friend"), whereas better mental health was related to less use of dominance-based training methods, lower perceived emotional/logistical costs of service dog partnership, and closer veteran-dog relationships. More frequent use of the trained service dog task to signal when someone approaches from behind (cover/watch back) was associated with greater anxiety, but less PTSD symptom severity. Overall, veterans spent an average of 82% of their time with service dogs (assessed via Bluetooth proximity between dog collar and veteran smartphone), and most frequently asked their service dogs to perform the trained task for calming their anxiety (calm/comfort anxiety). The present study provides subjective and objective metrics of the heterogeneity among veteran-service dog dyads while also suggesting which of the assessed metrics might be potential mechanisms involved in the intervention.

Quantifying the emotional experiences of partners of veterans with PTSD service dogs using ecological momentary assessment.

The objective of this study was to investigate the day-to-day experiences of positive and negative emotions among partners of veterans assigned service dogs for posttraumatic stress disorder (PTSD). As part of a larger clinical trial, a total of N = 87 partners of post-9/11 veterans with PTSD were recruited from a nonprofit service dog provider and participated in an ecological momentary assessment (EMA) protocol. The sample included partners of veterans who received a PTSD service dog after baseline (n = 48, treatment group) and partners of veterans on the waitlist for a service dog (n = 39, control group). Data were collected twice daily for two weeks at baseline and again at follow-up three months later, for approximately 56 assessments per participant (28 at baseline, 28 at follow up). Participants completed an average of 84% of questionnaires at baseline (n = 23.6) and 86% (n = 24.1) at follow-up. A total of 3780 EMA questionnaires were collected among partners for this analysis. Data were analyzed using a generalized linear mixed model. Three months following baseline, partners of veterans with service dogs reported statistically significant higher levels of positive emotions than the control partners (p = .01, d = 0.39) with small-to-medium effect sizes for each individual positive emotion. No statistically significant differences were reported for negative emotions (p = .77, d = 0.21). This study quantitatively identifies higher levels of positive emotion in partners who are cohabitating with a PTSD service dog compared to those partners who remained on the waitlist. Given the influence that positive emotions have on well-being and coping, findings suggest that the influence of service dogs may go beyond veterans to influence their cohabitating partners.