Abstract:Post-traumatic stress disorder (PTSD) affects 20–30% of US veterans. Greater PTSD symptom severity (PTSDSS) produces emotional dysregulation, impulsive behavior, and family/societal dysfunction. The frequency and insidiousness of PTSD demand empirically validated treatment. Service dogs are used to reduce PTSD symptoms in veterans. Anecdotal reports suggest training service dogs for other veterans also reduces PTSDSS for the veterans who train them, but data are lacking. Studies without comparison interventions also suggest that training service dogs would reduce veterans’ PTSDSS. This two-armed parallel randomized clinical trial examined the efficacy of a service dog training program (SDTP) versus a dog training video control intervention (CIG) for improving PTSDSS in veterans with PTSD (n=60). Both interventions consisted of eight sessions and included instruction in training service dogs. The SDTP included hands-on service dog training. The CIG did not include any contact with service dogs. PTSDSS was assessed at baseline, after four sessions, and after eight sessions. In linear mixed models with random intercepts and slopes, veterans’ PTSDSS decreased significantly (F(1, 53.850)=17.210, p<0.001, ES=0.45) from baseline to the end of the intervention. Decreases did not differ between interventions (F(1, 53.850)=0.319, p=0.575) and were greater for women than for men (F(1, 53.895)=5.216, p=0.026, ES=0.47). Results indicate that the SDTP was not more effective than the CIG for reducing PTSDSS among veterans. Findings suggest that the support provided through participation in a study, placebo effects, and gender influenced PTSDSS reductions. Differences in the responses of men and women require further investigation.