Dogs as Probiotics - University of Arizona study

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Everyone knows dogs are "man's best friend." But have you ever wondered, in addition to this emotional bond we have with dogs, whether there is a biological component that actually improves the health of both dogs and humans? These are the questions that we looked at in our UA dog study. 

We think dogs might work as probiotics to enhance the health of the bacteria that live in our guts. These bacteria or the “microbiota”,  are increasingly recognized as playing an essential role in our mental and physical health, especially as we age. 

Everyone knows dogs are “man’s best friend.” But have you ever wondered, in addition to this emotional bond we have with dogs, whether there is a biological component that actually improves the health of both dogs and humans? These are the questions that were explored in a novel study conducted at the University of Arizona’s Department of Psychiatry in partnership with the Humane Society of Southern Arizona and colleagues at the University of Colorado at Boulder.

Why The Microbiome Is Important

Thanks to recent advances in science, we know that the majority of the bacteria in our guts are an essential part of our ecosystem and are vitally important to maintaining all aspects of our physical and mental health. We know that not all bacteria are good; we can get very sick from the “bad” bacteria, and modern medicine has done a wonderful job of protecting us from various diseases that are created by these bacteria. But unfortunately, it seems, that by eliminating the bad bacteria we’ve started eliminating the “good” bacteria too.

This “good” bacteria can be thought of like a “probiotic”. Through research, we’ve learned that people who own dogs are much more likely to share the same kinds of these “good” bacteria with their dogs. (5) We have also learned that children who are raised with dogs are less likely than others to develop a range of immune related disorders, including asthma and allergies.(2,3,4) Suggesting that maybe dogs are enhancing the “good” bacteria in our bodies, and possibly improving our health.

We’ve all heard about probiotics through pills and yogurt, but what if owning a dog had the same effect on us? And what if they help improve the immune systems of the whole family?

Understanding The Microbiome Connection Between Older People And Dogs

We did  this study in older adults specifically to see if the changes science has shown for children can be replicated in older people, and to see if dogs can improve the physical and mental health of these adults. 

If dogs act as a sort of probiotic for dog owners, is it possible that they can have this same effect on people who haven’t lived with a dog ever or for a long period of time? In addition to bacteria, dogs are just great companions, so we are also interested in looking at whether the introduction of a dog into the home of older adults improves their sleep, their muscle and bone strength, their ability to move around, and their overall happiness and quality of life. 


Charles Raison, M.D.


Dr. Raison (Ray-Zahn), served as the Principal Investigator for this study. Dr. Raison’s work focuses on inflammation and the development of depression  in response to illness and stress. He aims to translate neurobiological findings into novel pharmacological and behavioral interventions for treatment resistant depression. The Raison Lab conducts research into how we can use strategies from our evolutionary past to treat and heal the body from modern-day health afflictions. As such, he is excited to lead this study which will look at whether the strong pro-social and pro-health effects humans experience from dogs might be related to changes in the microbiota as a result of keeping dogs as pets.



Dr. Lowry is an Associate Professor in the Department of Integrative Physiology and Center for Neuroscience at the University of Colorado Boulder. Dr. Lowry's Behavioral Neuroendocrinology Laboratory, is internationally recognized for its contributions to understanding the role of brain sertonergic systems in health and disease. Dr. Lowry's laboratory conducted the seminal work that encouraged the idea for this study. He served as a scientific advisor to the team for the dog study. 


Dr. Knight is a Professor at the BioFrontiers Institute and in the Departments of Chemistry & Biochemistry and Computer Science at the University of Colorado at Boulder. The Knight Lab has recently moved to San Diego, and it continues to be a world-leader  in computational approaches to determining microbiome composition and functionality in both humans and non-human animals. Dr. Knight’s team is overseeing the analysis of the human and canine fecal and skin samples.


Dr. Kelly is a Medical Anthropologist whose research focuses on animal-human relations and contemporary American views (both scientists’ and lay persons’) on the use of non-human animal bodies as proxies for human ones in science.  She has over fifteen years health research experience with expertise in global health and infectious disease, the anthropology of clinical trials, mixed methods research design and implementation, program development and evaluation, and clinical trial operations and management. Dr. Kelly served as principal research lead on this study. Additionally, she was the program coordinator of HAIRI and co-founder of the University of Arizona's Palm Oil Awareness Initiative (POAI). 



Dr. Steklis is a Professor of Psychology and Anthropology at the University of Arizona. Dr. Steklis’ present research focuses on the comparative study of paternal behavior, personality and temperament, cognitive and emotional differences between apes and humans, and play behavior in mountain gorillas. Dr. Steklis is considered a prominent primatologist and animal behavior specialist and will play a key role in designing and analyzing that component of our study. Additionally, he is a Co-Chair of HAIRI.

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Ms. Steklis is a Lecturer in Family Studies and Human Development at the University of Arizona. Her research experience includes the behavioral ecology of wild chimpanzees in eastern Zaire and research at the Karisoke Research Center in Rwanda on the social organization of mountain gorillas. She is currently interested in the comparative study of cognition, personality and life history, the study of primate social systems and families, the biopsychology of human-animal interactions, and conservation education. Currently she is working toward a Ph.D. in Ethology & Evolutionary Psychology (expected 2017). She is considered a prominent primatologist and animal behavior specialist and played a key role in designing and analyzing that component of our study. Additionally, she is a Co-Chair of HAIRI.


Dr. Curran is an Associate Professor in the Family Studies and Human Development Department of the Norton School of Family and Consumer Sciences.  Her work focuses largely on the theories of attachment, interdependence, symbolic interactionism, family systems, and commitment. She has bridged these areas of study with a focus on examining the transition to parenthood for pregnant, unmarried, cohabitors and continues to study relational sacrifices and relationship quality (e.g., commitment, satisfaction), as well as beliefs about relationships and marriage. Additionally, Dr. Curran uses her expertise in these areas to assist HAIRI researchers with understanding the bonds and relationships humans form with animals, particularly attachment and commitment bonds.  In the Dogs as Probiotics for People study she worked closely with Dieter and Netzin Steklis to develop appropriate measures and train undergraduate and graduate staff members to implement these tools and analyze data obtained from their administration.


Dr. Janssen is a Human Development and Family Studies expert whose research focuses on evolutionary psychology and nutrition and psychophysiology.  Dr. Janssen  led the coordination and analysis of the heart rate variability and physiologic measures to be performed on both the dog and human study participants.


Dr. Garcia received his Bachelor’s degree in Exercise Science from Slippery Rock University and his Master’s Degree and his PhD in Exercise Physiology from the University of Pittsburgh. Prior to pursuing his doctoral studies, he worked at the University of Pittsburgh Physical Activity and Weight Management Research Center where he assisted with numerous National Institutes of Health funded research studies examining the effects of exercise on weight loss and weight maintenance in overweight and obese individuals. These studies have provided him with invaluable experience in individual exercise counseling and group weight management. In addition, he has developed and implemented physical activity and weight management programs for corporate and community partners.  Dr. Garcia was awarded a R25T Cancer Prevention and Control Fellowship in April 2014 and selected Cynthia Thomson, PhD (College of Public Health) as his primary mentor. Cecelia Rosales, MD (College of Public Health), Bijan Najafi, PhD, M.Sc. (College of Medicine), and Melanie Bell, PhD (College of Public Health) also serve on his mentoring team. Dr. Garcia’s R25 research will promote physical activity with healthy dietary behaviors and weight management as it relates to cancer risk reduction and survivorship with a particular emphasis on health disparities in Hispanics.

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Jordan is an undergraduate physiology and molecular biology student with focus in nutrition and biochemistry at the University of Arizona. He is interested in studying stress and inflammation and ways to manage these responses through integrative practices. His interest in the Dog Study is to learn more about how living with a dog influences the body's natural stress and inflammatory responses from a biochemical standpoint and will be assisting in all aspects of the study.

Annie is a undergraduate psychology major at the University of The Arizona, minoring in French and fluent in Spanish. She is interested in the processes of aging and enjoys working with older populations in research settings. Annie is interested in animals, nature, and staying active! 


Sky is an undergraduate neuroscience student at the University of Arizona. She has worked with shelter dogs for over seven years. She plans to study canine cognition in her career and will assist in all aspects of study coordination.


Ron is an undergraduate Family Studies and Human Development student at the University of Arizona. He is interested in the study of attachment theory and how animals fulfill the need for attachment. He plans to continue his education in Family Studies or in Marriage and Family Therapy. 


Dr. Song is a researcher whose work focuses on the factors that influence the evolution of host-microbe interactions and determine the composition of microbial communities associated with vertebrate hosts (including humans). Dr. Song served as a scientific advisor for the study.

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