Caroline Cassels

May 16, 2016

ATLANTA ― Adopting a pet dog may be a useful therapeutic adjunct for veterans with posttraumatic stress disorder (PTSD), preliminary research suggests.

Results of a 6-month randomized pilot study showed that adopting a dog reduced PTSD symptoms and had a significant impact in reducing symptoms of depression and loneliness in a group of veterans with PTSD.

"Pet dog adoption helped alleviate PTSD symptoms, depression, and loneliness in most of the veterans in our study. These results suggest adopting a pet dog from an animal shelter may be a useful adjunct to treatment for some veterans with PTSD," principal investigator Stephen Stern, MD, told reporters attending a press briefing here at the American Psychiatric Association (APA) 2016 Annual Meeting.

Randomized Trial

According to the researchers, despite significant treatment advances, many veterans continue to suffer from PTSD, suggesting a need for new interventions.

The idea for this research, said Dr Stern, adjunct professor, University of Texas Health Science Center at San Antonio, and research investigator, South Texas Veteran Health Care System," came from the many veterans in our clinics who anecdotally told us how much their pet dog had helped them."

Dr Stephen Stern

Dr Stern has been working at the San Antonio VA PTSD clinic for just over 10 years. Very early on in his tenure, he noted the positive impact pet dogs had on his patients.

"Just in my first 3 or 4 weeks there I was struck by how many veterans, just in the course of clinical sessions, talked about how much comfort they got from their pet dog, and when I spoke with my colleagues, they reported similar interactions with their patients," Dr Stern told Medscape Medical News.

This observation led to a small, preliminary study of 30 veterans with PTSD who had pet dogs. The study, which was published in Society and Animals (2013;6:568-581), explored how the dogs were helpful to them. It found that veterans with PTSD who adopted a pet dog reported feeling calmer, less lonely, less depressed, and less anxious about their personal safety and the safety of their family. That study was the impetus for the current study.

The primary goal of the current 6-month pilot study was to examine whether adopting a pet dog as a supplement to usual care would reduce psychological distress in veterans with PTSD over a 3- month period compared with a wait-list control group. It is important to note, said Dr Stern, that the dogs were pets and not service animals.

The study included 19 veterans who met DSM-5 criteria for current PTSD, as determined by a score of 39 or more on the PTSD Checklist (PCL-5).

All participants were in active treatment for the disorder, were free from current substance abuse/dependence, mania, psychosis, or significant suicidal or homicidal ideation, and had not lived with a dog or other companion animal for the past 12 months.

At the end of the initial baseline evaluation, veterans were randomly assigned to either immediate dog adoption (n = 9) from the Humane Society or a 3-month wait list followed by dog adoption (n = 10).

A total of nine veterans were assigned to the dog group; 10 were assigned to the control group; 42% of the study participants were women. There were no significant differences between the two groups with respect to age, sex, ethnicity, or type of traumatic event.

Large Impact on Depression, Loneliness

Once a veteran was assigned to adopt a pet, the Humane Society's chief veterinarian selected several dogs for him or her to choose from. Dogs with behavioral or significant medical problems were excluded.

Throughout the study, veterans and their dogs received close support from the study team. This included eight sessions of free obedience training from the Humane Society veterinarian as well as free veterinary care.

The study's primary outcome measure was change in PCL-5 score from baseline. The research also assessed potential changes in depressive symptoms using the Patient Health Questionnaire 9 (PHQ-9) as well as symptoms of loneliness using the UCLA Loneliness scale.

Quantitative data were analyzed using mixed effects regression models with repeated measures. During the 3-month period following randomization, mean PCL-5 scores improved by 15.2 (3.5) points in the dog group ― a clinically significant change ― and 7.8 (3.3) points in the control group.

The effect size of the group difference was medium at 0.7, although the P value was not significant, at 0.141. The lack of statistical significance here, said Dr Stern, was likely due to the small number of study participants.

However, results showed a large effect size on depression and loneliness. Mean scores on the PHQ-9 depression scale improved by 4.1 (1.2) points in the dog group and worsened by 0.7 (1.1) points in the control group, and scores on the UCLA Loneliness Scale improved by 7.8 (3.5) points in the dog group and worsened by 3.4 (3.3) points in the control patients. Effect sizes for both scales were very large (1.1 and 1.2, respectively), and P values were significant (.010 and .031).

In semistructured interviews, most veterans in the dog group reported developing close bonds with their pet and becoming more physically and socially active. They also described improvements in their overall happiness, ability to cope with stress, and relationships with others.

A Potential Win/Win

Although further research is needed, these initial findings suggest that adopting a pet dog may prove a useful adjunct to treatment for veterans with PTSD.

A dog-lover himself, Dr Stern and his wife have adopted three dogs from the Humane Society over the years, including his current pooch, Tails.

"If further research confirms our findings and pet dog adoption becomes more widely used, it might also benefit society by reducing the number of homeless animals," said Dr Stern.

Commenting on the findings for Medscape Medical News, Jeffery Borenstein, MD, APA chair of the Council on Communications and president and CEO of Brain and Behavior Research, said the findings are promising.

"I think that for a number of psychiatric conditions, being able to have evidence that adjunctive treatments that augment standard therapies, including talk therapies, medication, etc, offers us a tremendous advantage. In this particular study, the researchers clearly showed that veterans who received the active treatment did much better, and I think this is a very useful findings," he said.

The authors and Dr Borenstein report no relevant financial relationships.

American Psychiatric Association (APA) 2016 Annual Meeting: Abstract 6282, presented May 14, 2016.


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