Human Animal Interaction

Why walking shelter dogs could benefit military veterans struggling with PTSD

A study funded in part by the ISAZ/Waltham Collaborative Research Award and C-P.A.W.W.® research programme has shown walking with shelter dogs can have a positive impact on veterans’ perceived stress and PTSD symptoms.

The 8-week study is one of the first designed to examine if dog interaction might benefit military veterans’ mental health. Researchers from Florida Atlantic University, the University of Maryland and Virginia Commonwealth University examined 33 veterans in Colorado (US), over half of whom identified as struggling with PTSD.

The veterans walked shelter dogs once a week along a pre-established walking path for four weeks. As a control group, the same participants also took walks with humans once a week along the same path.

Researchers measured participants’ physiological stress indicators, including heart rate variability, salivary cortisol and alpha amylase, as well as their reported psychological stress, during and after the walks. The heart rate variability biomarker was found to have the strongest correlation with human physical stress and psychosocial stress levels during and right after the walks.

Results showed that the veterans with PTSD had improved levels of both physiological and psychological stress indicators after their walks with both humans and dogs. But researchers also found these stress indicators were often better when the veterans walked with shelter dogs. The improvement was even more notable in veterans with higher levels of reported PTSD symptoms.

PTSD affects 1 in 5 of the 21 million veterans living in the United States, and around 150,000 veterans living in the United Kingdom. Research shows that animal-assisted interventions (AAI) are linked to overall better health and stress management, and that adults with pets can experience better outcomes after suffering from a cardiovascular event such a stroke or a heart attack. Pets can also play an important role in helping to relieve loneliness and feelings of isolation.



Our findings emphasize the need for more research to determine if this form of human-animal interaction is beneficial to veterans with post-traumatic stress disorder and to help us identify the optimal dosage that will be most impactful for them”,said Cheryl Krause-Parello, lead author, a professor and director of C-P.A.W.W.® within FAU’s Christine E. Lynn College of Nursing, and a faculty fellow of FAU’s Institute for Human Health and Disease Intervention (I-HEALTH).

Interactions such as walking with shelter volunteers also have an impact on the dogs themselves. Regular walks and training sessions can improve their socialisation, reduce their stress, and provide important physical and mental exercise, which can greatly improve their health and wellbeing.


A happier and more relaxed shelter dog is also more likely to be adopted. There are an estimated 3.9 million shelter dogs in the U.S. alone waiting for adoption, a figure that almost matches the number of U.S. military veterans living with PTSD. The opportunity to better understand human-animal interaction is also a chance to make a positive impact on reducing dog homelessness.

Further research is needed to answer additional questions related to the nature of the animal interaction that may have contributed to the positive results in this study. Larger, long-term studies including other vulnerable groups could help explain some of the mechanisms behind human-animal interaction, which might also help experts develop personalised animal-assisted therapy programmes.

At Mars Petcare, we believe we have a responsibility to take scientific exploration further when evidence to date shows us that pets can be part of addressing conditions like PTSD”, said Waltham Vice President, Kay O’Donnell. “We’re also proud to be part of a study that helped dogs in shelters socialise and interact. "It’s important we continue to undertake rigorous studies to understand how companion animals may provide a benefit to us and advance understanding of the human-animal bond – for both pets and people.

Read the full study