Research into Human-Animal Relationships

The Institute for Human-Animal Connection's (IHAC) research explores how human-animal interactions affect individual and community health and well-being. Our work is conducted within a framework of social justice and equity for humans and other species.

IHAC Staff with Farm Animals, at Animal Assisted Therapy and Nature Assisted Therapy

Human-Animal Interactions and Mental Health

This area of our research seeks to understand how interactions with other species affect people’s mental health. Our studies focus on youth in clinical treatment, military veterans with PTSD, people participating in dog training programs while in prison, and adults with companion animals.

Youth in Mental Health Treatment

Does including animal-assisted and other nature-based interventions in residential treatment improve developmental outcomes for youth? IHAC is conducting research at Green Chimneys, a school and treatment facility that is world renowned for incorporating these interventions throughout their clients’ clinical treatment. Using the Positive Youth Development framework, IHAC is showing that the Green Chimneys experience supports students’ improved social-emotional functioning. This research is creating an evidence base for incorporating animal-assisted and nature-based interventions into clinical treatment of youth at Green Chimneys that can be applied in other environments.

Service Dogs for Military Veterans with PTSD

How do service dogs impact veterans’ post-traumatic stress (PTSD) symptoms? While there is a growing body of evidence showing that service dogs improve some of the symptoms of PTSD, IHAC is delving deep into the biology of how this human-animal interaction leads to improved lives for military veterans. Our study also investigates impacts on service dog health and well-being. This research is anticipated to generate new biomarkers for tracking clinical changes to PTSD symptoms, novel targets for drug development, and blood panels that can be used to optimize protocols for keeping service dogs healthy and thriving.

Prison-Based Dog Training Programs

How does participating in dog training programs affect outcomes for people in prison? IHAC’s research has shown that dog training program participants have a 15% lower likelihood of returning to prison after release. Our research is also revealing a variety of potential reasons for this improvement, including greater empathy from working with people of diverse racial and ethnic backgrounds on dog training teams. This research provides an important foundation of evidence that these programs improve the lives of both the people in prison and the dogs in these programs.

Adults with Companion Animals

How do our companion animals affect our mental health? While most people accept the idea that our relationships with our pets reduce our stress levels, IHAC’s research suggests that they may actually keep us in a healthy zone of response to everyday stressful situations. With over half of U.S. households including dogs and cats, this research is adding nuance to our understanding of how our relationships with these companions may increase human health and well-being.

Featured Publications

Bello, B., Flynn, E., Geldhof, G.J., Yu, D., Mueller, M.K., & Morris, K.N. (2024). Measuring social and emotional functioning as a facet of Positive Youth Development among children and adolescents with mental health and learning challenges. Social Development. e12738. doi: 10.1111/sode.12738
Gandenberger, J., Ledreux, A., Taeckens, A., Murphy, K., Forkin, J., Gilmore, A., & Morris, K. N. (2024). The Presence of a Pet Dog Is Associated with a More Balanced Response to a Social Stressor. Stresses, 4(3), 598-613.
Wesley, J., Furst, G., Bello, B., & Morris, K.N. (2024). How prison dog programs challenge the racial code in correctional settings and beyond. Corrections: Policy, Practice, and Research. In press. doi: 10.1080/23774657.2024.2338848
Han, T., Flynn, E., Pena, R., & Morris, K.N. (2023). Measuring the impact of prison-based dog training programs on recidivism: A propensity score-matched survival analysis. Journal of the Society for Social Work and Research. In press. doi: 10.1086/727360
Collaborators
Some of our collaborators include:
- Assistance Dogs International
- Green Chimneys
- SomaLogic

Pets Access to Care Research Study Team with Pet Smart Charities

Human-Animal Interactions and Equity

This area of our research seeks to understand inequity experienced by individuals and families who live with companion animals. Our studies focus on the effects of creating access to veterinary care, the impacts of animal law enforcement on communities, and best practices for animal sheltering.

Access to Veterinary Care

What are the most effective ways to create equitable access to veterinary care for families living in under-resourced and historically marginalized communities? IHAC is conducting research with partners, including The Humane Society of the United States’ Pets for Life, PetSmart Charities, and Tufts University, to understand what barriers exist and how to most effectively eliminate them to create opportunities for all families to access care for their companion animals. Further, we are showing how creating equitable access to veterinary care affects human, community, and environmental health, within the One Health framework. This research supports the development of public policies that include access to health care for companion animals as well as people.

Animal Law Enforcement

Do animal control agencies engage equitably with the jurisdictions they serve? IHAC is conducting research using data provided by large municipal animal control agencies to understand enforcement patterns and trends across jurisdictions. Our findings show that animal laws and ordinances are not only enforced at higher rates in historically marginalized communities, but also members of those communities experience more punitive outcomes. Further, a community’s racial and ethnic makeup was found to be the strongest driver behind the measured differences. This research is contributing to the conversation about how animal welfare agencies of all types can better engage with under resourced and historically marginalized communities.

Animal Sheltering

How do best animal sheltering policies and practices increase equity for the community they serve? IHAC is conducting research in animal shelters to understand how their ability to effectively engage with all the communities they serve affects outcomes for both shelter animals and the greater community. IHAC’s work in this area continues to inform shelter policies and practices across the U.S.

Featured Publications

Hawes, S.M., O’Reilly, K.M., Mascitelli, T.M., Winczewski, J., Dazzio, R., Arrington, A., & Morris, K.N. (2024). Measuring the One Health impacts associated with creating access to veterinary care before and during the COVID-19 pandemic. Frontiers in Public Health. In press. doi:10.3389/fpubh.2024.1454866
Mascitelli, T.M., Graham, T., Loney, L., Applebaum, J.W., Murray, C., Binna-Calvey, M., Hawes, S.M., & Morris, K.N. (2024). Barriers to finding and maintaining pet-inclusive affordable housing: Tenant experiences from Houston, Texas. Frontiers in Veterinary Medicine. Vol. 11. doi: 10.3389/fvets.2024.1465682
Hawes, S.M., Rhodes, T., Hupe, T.M., Dazzio, R., Flynn, E., O’Reilly, K., & Morris, K.N. (2024). The development and validation of the One Health Community Assessment. One Health, 18, 100722.
Hawes, S. M., Hupe, T., Winczewski, J., Elting, K., Arrington, A., Newbury, S., & Morris, K. N. (2021). Measuring changes in perceptions of access to veterinary care in underserved communities. Frontiers in Veterinary Medicine.
Moss, L.R, Hawes, S.M., Connolly, K., Bergstrom, M., O'Reilly, K., Morris, K.N. (2023). Animal Control and Field Services Officers’ Perspectives on Community Engagement: A Qualitative Phenomenology Study. Animals, 13, 68. https://doi.org/10.3390/ani13010068.
Collaborators
Some of our collaborators include:
- The Humane Society of the United States
- The Humane Society of the United States Pets for Life
- National Animal Care & Control Association
- PetSmart Charities
- Tufts University Cummings School of Veterinary Medicine

IHAC Research Team Highlights

Liana and Kaleigh outside, research associate and research fellow

Dr. Kevin Morris, Liana Moss, and Kaleigh O'Reilly recently presented groundbreaking insights from our study on animal control patterns across the United States. With over 1 million cases in our analysis, we revealed key patterns in demographic disparities within animal control interactions. For the first time, IHAC is taking a detailed look at how animal control agencies are engaging with the communities they serve.

Watch the presentation

Research Associate Jaci Gandenberger with pet dog Sophie

The Institute for Human-Animal Connection’s study on social stressors found evidence to support the hypothesis that the presence of a pet dog can assist in a healthy stress response. This study was the first of its kind to test levels on multiple physiological systems, allowing us to come to the presumption that dogs may be able to support a balanced, intermediate stress response. Instead of just reducing the stress response, a dog can actually help to maintain balanced stress levels.

Selected Publications

Reach out to us at ihac@du.edu to request access to a full paper.

2025

Flynn, E., Valdovinos, M., Mueller, M.K., & Morris, K.N. (2025). A relational developmental theory of human-animal interaction: A meta-synthesis and grounded theory. Developmental Review. 75. doi 10.1016/j.dr.2024.101181
Sidel, S. B., Gandenberger, J., Murphy, K., & Morris, K. N. (2025). Recognizing and Mitigating Canine Stress in Human–Canine Interaction Research: Proposed Guidelines. Animals, 15(11), 1665.
2024

Bello, B., Flynn, E., Geldhof, G.J., Yu, D., Mueller, M.K., & Morris, K.N. (2024). Measuring social and emotional functioning as a facet of Positive Youth Development among children and adolescents with mental health and learning challenges. Social Development. e12738. doi: 10.1111/sode.12738
Chastain Griffin, T., Steward, L., & Ekholm Fry, N. (2024). Standards of practice in animal-assisted interventions. In A. H. Fine, M. K. Mueller, Z. Y. Ng, T. Chastain Griffin, & P. Tedeschi (Eds.). Handbook on Animal-Assisted Therapy, (6th ed., pp. 97-109). Academic Press.
Ekholm Fry, N. (2024). Equine welfare in therapy and learning services: An overview. In L. Kogan (Ed). Animal-assisted interventions: Recognizing and mitigating potential welfare challenges (pp. 14-17). CAB International.
Ekholm Fry, N. (2024). Specific welfare considerations for animals involved in animal-assisted interventions: Equines. In A. H. Fine, M. K. Mueller, Z. Y. Ng, T. Chastain Griffin, & P. Tedeschi (Eds.). Handbook on Animal-Assisted Therapy, (6th ed., pp. 278-291). Academic Press.
Fine, A. H., Flynn, E., Hawes, S., Elvove, E., Feldman, S., Braun, L., & O’Reilly, K. M. (2024). Forward thinking: The evolving fields of human-animal interactions and animal-assisted interventions. In A. H. Fine, M. K. Mueller, Z. Y. Ng, T. Chastain Griffin, & P. Tedeschi (Eds.). Handbook on Animal-Assisted Therapy, (6th ed., pp. 27-43). Academic Press.
Gandenberger, J., Ledreux, A., Taeckens, A., Murphy, K., Forkin, J., Gilmore, A., & Morris, K. N. (2024). The Presence of a Pet Dog Is Associated with a More Balanced Response to a Social Stressor. Stresses, 4(3), 598-613.
Hawes, S.M., Rhodes, T., Hupe, T.M., Dazzio, R., Flynn, E., O’Reilly, K., & Morris, K.N. (2024). The development and validation of the One Health Community Assessment. One Health, 18, 100722. doi: 10.1016/j.onehlt.2024.100722
Hawes, S.M., O’Reilly, K.M., Mascitelli, T.M., Winczewski, J., Dazzio, R., Arrington, A., & Morris, K.N. (2024). Measuring the One Health impacts associated with creating access to veterinary care before and during the COVID-19 pandemic. Frontiers in Public Health. In press. doi:10.3389/fpubh.2024.1454866
Mascitelli, T. M., Graham, T. M., Loney, L., Applebaum, J. W., Murray, C. M., Binns-Calvey, M., ... & Morris, K. Barriers to finding and maintaining pet-inclusive affordable housing: Tenant experiences in Houston, Texas. Frontiers in Veterinary Science, 11, 1465682.
Wesley, J., Furst, G., Bello, B., & Morris, K.N. (2024). How prison dog programs challenge the racial code in correctional settings and beyond. Corrections: Policy, Practice, and Research. In press. doi: 10.1080/23774657.2024.2338848
2023

Cardona, A., Hawes, S.M., Cull, J., Connolly, K., O’Reilly, K., Moss, L.R., Bexell, S., Yellow Bird, M., & Morris, K.N. (2023). Perspectives on rez dogs on the tribal lands of the Mandan, Hidatsa, and Arikara Nation at Fort Berthold, North Dakota, USA. Animals, 13, 1422. doi: 10.3390./ani13081422.
Connolly, K. & Ekholm Fry, N. (2023). The state of coursework on horses in human services at universities and colleges in the United States: A scoping review. Frontiers in VeterinaryScience: Veterinary Humanities and Social Sciences, 10.
Flynn, E., Motiff, M., Mueller, M.K., & Morris, K.N. (2023). Testing the Facial Expression Coding System (FACES) for middle school aged special education students and development of a protocol. International Journal of Behavioral Development. doi: 10.1177/01650254231167313.
Flynn, E., Motiff, M., Taeckens-Seabaugh, A., Mueller, M.K., & Morris, K.N. (2023). Promoting youth social-emotional development through animal-assisted interventions: A qualitative analysis of special education students’ perspectives. Applied Developmental Science. In press. doi: 10.1080/1088691.2023.2235265
Gandenberger, J., & Ekholm Fry, N. (2023). Human-animal-environment interactions in social work at the University of Denver. In L. Kogan (Ed). Careers in One Health: Social Workers’Roles in Caring for Humans and Their Animal Companions (pp. 207-210). Routledge.
Gerhardt, R., Flynn, E., & Morris, K.N. (2023). A scoping review of research on canine-assisted interventions to reduce loneliness and promote socializing behaviors in early and middle adulthood. Health Sciences Review. doi: 10.1016/j.hsr.2023.100076.
Han, T., Flynn, E., Pena, R., & Morris, K.N. (2023). Measuring the impact of prison-based dog training programs on recidivism: A propensity score-matched survival analysis. Journal of the Society for Social Work and Research. In press. doi: 10.1086/727360
Hawes, S., Gutierrez, L. J., Rojas, L., Cohen, R., Camacho, B, Taeckens-Seabaugh, A., Hupe, T., & Ekholm Fry, N. (2023). Diversity, equity, inclusion, and belonging in human-animal interactions: Reflections on practice. In A. H. Fine, M. K. Mueller, Z. Y. Ng, A. M. Beck, &J. M. Peralta (Eds.). The Routledge International Handbook of Human-Animal Interactionsand Anthrozoology. Routledge.
Moss, L.R, Hawes, S.M., Connolly, K., Bergstrom, M., O'Reilly, K., Morris, K.N. (2023). Animal Control and Field Services Officers’ Perspectives on Community Engagement: A Qualitative Phenomenology Study. Animals, 13, 68. https://doi.org/10.3390/ani13010068.
Taeckens, A., Corcoran, M., Wang, K., and Morris, K.N. (2023). Examining human-animal interactions and their effect on multidimensional frailty in later life: A scoping review. Frontiers in Public Health. 11. doi: 10.3389/fpubh.2023.1214127
2022

Gandenberger, J., Flynn, E., Moratto, M., Wendt, A., & Morris, K. N. (2022). Molecular biomarkers of adult human and canine stress during human-canine interactions: A systematic scoping review. Animals, 12, 651. doi: https://doi.org/10.3390/ani12050651.
Gandenberger, J., Motiff, M., Flynn, E., & Morris, K.N. (2022). Staff perspectives on the targeted incorporation of nature-based interventions for children and youth. Residential Treatment for Children and Youth. doi: 10.1080/0886571X.2022.2096169.
Hawes, S.M., Flynn, E., Tedeschi, P., and Morris, K.N. (2022). Humane communities: social change through policies promoting collective welfare. Animals in the City. (Chapter 13, pp 306-319). New York, USA: Routledge. 1st Edition.
Hawes, S. M., Gutierrez, L., Rojas, L., Cohen, R., Camacho, R, Taeckens-Seabaugh, A., Hupe, T., & Ekholm Fry, N. (In Press). Diversity, equity, inclusion, and belonging in human-animal interactions: Reflections on practice. In Fine, Mueller, Ng, Peralta, & Beck (Eds.), The Handbook on Human-Animal Interactions, Interventions, and Anthrozoology.
Howell, T. J., Nieforth, L., Thomas-Pino, C., Samet, L., Agbonika, S., Curevas-Pavincich, F., Ekholm Fry, N., Hill, K., Jegatheesan, B., Kakinuma, M., Macnamara, M., Mattila-Rautiainen, S., Perry, A., Tardif-Williams, C., Walsh, E., Winkle, M., Yamamoto, M., Yerbury, R., Vijay, R…Bennett, P. (2022). Defining terms used for animals working in support roles for people with support needs. Animals, 12, 1975.
Rodriguez, J.R., Davis, J., Hill, S., Wolf, P.J., Hawes, S.M., & Morris, K.N. (2022). Trends in intake and outcome data from U.S. animal shelters from 2016 to 2020. Frontiers in Veterinary Science. 9:863990. doi: 10.3389/fvets.2022.863990.

Taeckens-Seabaugh, A. (2022). Conducting diversity, equity, and inclusion-informed research with older adults. Innovation in Aging. In press.
2021

Ekholm Fry, N. (2021). Conceptualization of psychotherapy incorporating equine interactions in the United States. Human-Animal Interaction Bulletin,9(3), 94-114.
Ekholm Fry, N. (2021). Welfare considerations for horses in therapy and education services. In J.M. Peralta & A. H. Fine (Eds.). The Welfare of Animals in Animal Assisted Interventions: Foundations and Best Practice Methods (pp. 219-242). Springer.
Flynn, E., Zoller, A. G., Gandenberger, J., & Morris, K. N. (2021). Improving engagement in behavioral and mental health services through animal-assisted interventions: A scoping review. Psychiatric Services. 00:1-8. doi: 10.1176/appi.ps.202000585
Gandenberger, J., Flynn, E., Mueller, M., & Morris, K.N. (2021). The impacts of a nature-based mentorship program on students’ self-regulation: Harnessing the anticipation effect.
Gandenberger, J., Hawes, S. M., Wheatall, E., Pappas, A., & Morris, K. N. (2021). Developing the Animal Welfare Cultural Competence Inventory (AWCCI) to assess cultural competence in animal welfare. Journal of Applied Animal Welfare Science. doi: 10.1080/10888705.2021.2008934.
Geldhof, G. J., Flynn, E., Mueller, M. K., Gandenberger, J., Witzel, D., & Morris, K. N. (2021). Emotion regulation and specificity: The impact of animal-assisted interventions on classroom behavior. Journal of Applied Developmental Psychology, 73, 1-9. https://doi.org/10.1016/j.appdev.2021.101253.
Gu, X., Bexell, S. M., Wang, B. (2021). Attitudes toward animals during the outbreak of novel coronavirus in China. Anthrozoos. DOI:10.1080/08927936.2021.1974701.
Hawes, S. M., Hupe, T., Gandenberger, J., & Morris, K. N. (2021). Temporal trends in intake data for animal shelters and rescues in Colorado, 2008 to 2018. Journal of the American Veterinary Medical Association.
Hawes, S. M., Hupe, T., Gandenberger, J., Saucedo, M., Arrington, A., & Morris, K.N. (2021). Detailed assessment of pet ownership rates in four underserved urban and rural communities in the United States. Journal of Applied Animal Welfare Science. doi: 10.1080/10888705.2021.1871736
Hawes, S. M., Hupe, T., Winczewski, J., Elting, K., Arrington, A., Newbury, S., & Morris, K. N. (2021). Measuring changes in perceptions of access to veterinary care in underserved communities. Frontiers in Veterinary Medicine.
Motiff, M. & Morris, K.N. (2021). Nature-based interventions for children with special needs. Exchange, November/December issue, 12-15.
Van Buiten, H., Flynn, E., & Morris, K. N. (2021). Dog training as a complimentary intervention to support veteran mental health and well-being: A scoping review. Complementary Therapies in Clinical Practice, 44, 1-7. https://doi.org/10.1016/j.ctcp.2021.101425
2020

Flynn, E., Gandenberger, J., Mueller, M. K. Morris, K. N. (2020). Animal-assisted interventions as an adjunct to therapy for youth: Clinician perspectives. Child and Adolescent Social Work Journal.
Han, T.M., Gandenberger, J., Flynn, E., Sharma, J., and Morris, K.N. (2020). Empowerment theory and prison-based dog training programs: Implications for social work. Journal of Social Work. In Press.
Hawes, S.M. Hupe, T. Morris, K.N. (2020). Punishment to support: The need to align animal control enforcement with the human social justice movement (Commentary). Animals, 10, 1902. doi: 10.3390/ani10101902.
Hawes, S.M., Ikizler, D., Loughney, K., Temple Barnes, A., Marceau, J., Tedeschi, P. and Morris, K.N. (2020). A quantitative study of Denver’s breed-specific legislation. Animal Law Review, 26(2). 195-271.
Hawes, S.M., Kerrigan, J.M., Hupe, T., Morris, K.N. (2020). Factors informing the return of adopted dogs and cats to an animal shelter. Animals, 10, 1573. doi: 10.3390/ani10091573.
2019

Bexell, S. M., Clayton, S., & Myers, G. (2019). Children and animals: Incorporating the importance of human-other animal relationships in fostering resilience in children. In P. Tedeschi & M. Jenkins (Eds.), Transforming trauma: Finding resiliency and healing through animals (pp. 217–240). Lafayette, IN: Purdue University Press.
Clayton, S., Bexell, S. M., Xu, P., Tang, Y. F., Li, W. J., & Chen, L. (2019). Environmental literacy and nature experience in Chengdu, China. Environmental Education Research.
Ekholm Fry, N. (2019). Horses in the treatment of trauma. In P. Tedeschi & M. Jenkins (Eds.), Transforming trauma: Finding resiliency and healing through animals (pp. 265–298). Lafayette, IN: Purdue University Press.
Flynn, E., Zoller, A.G., Mueller, M. K., & Morris, K. N. (2019). Human-Animal-Environment Interactions as a Context for Child and Adolescent Growth. Journal of Youth Development, 14(4), 144-163. doi:10.5195/jyd.2019.839
Flynn, E., Massey Combs, K., Gandenberger, J., Tedeschi, P., and Morris, K. N. (2019). Measuring the psychological impacts of prison-based dog training programs and in-prison outcomes for inmates. The Prison Journal, 100(2), 224-239. doi: 10.1177/0032885519894657.
Hawes, S.M., Camacho, B.A., Tedeschi, P. and Morris, K.N.(2019). Temporal trends in intake and outcome data for animal shelters in Colorado, 2000 to 2015. Journal of the American Veterinary Medical Association. 254(3), 363-372. doi:10.2460/javma.254.3.363
Hawes, S. M., Flynn, E., Tedeschi, P. and Morris, K. N. (2019). Humane Communities: Social change through policies promoting collective welfare. Journal of Urban Affairs, 1-13. doi: 10.1080/07352166.2019.1680244.
Hawes, S., Ikizler, D., Loughney, K. Marceau, J.F., Tedeschi, P. and Morris, K.N. (2019) The Impacts of the City and County of Denver’s Breed Specific Legislation. Speciesism and Breed Discrimination Collection. 5.
2018

Ascione, F. R., McDonald, S. E., Tedeschi, P. & Williams, J. H. (2018). The Relations among Animal Abuse, Psychological Disorders, and Crime: Implications for Forensic Assessment. Behavioral Sciences & The Law Special Issue.
Bexell, S. M., Decker-Sparks, J. D., Tejada, J. & Rechkemmer, A. (2018). An analysis of inclusion gaps in sustainable development themes: Findings in recent social work research. International Social Work 00(0) 1-13.
Clayton, S., Bexell, S.M., Xu P., Zhang, Z.H., Li, W. J., Chen, H. W., & Hu, Y. (2018). Confronting the wildlife trade through public education at zoological institutions in Chengdu, China. Zoo Biology 37(2) 119-129.
Ekholm Fry, N. (2018). Equine-assisted therapy for trauma-accidents. In K. Trotter & J. Baggerly (Eds.). Equine-assisted mental health for healing trauma (125-139). New York, NY: Routledge.
Ekholm Fry, N., Meszaros, E., & O’Neill, K. (2018). Coursework in equine-assisted activities and therapies at universities and colleges in the United States: A scoping review. Human-Animal Interaction Bulletin, 6, 118-126.
Fine, A. Tedeschi, P. Mackintosh, T. Boone, J. (2018). Fostering a More Humane University Environment Through Course Work, Service-Learning, and Animal-Assisted Interventions and Activities. Human-Animal Interaction Bulletin, 6, 105-117.
Flynn, E., Roguski, J., Trujillo, K., Tedeschi, P. and Morris, K.N. (2018). The impacts of an animal-assisted therapy as an adjunct to intensive family services among Child Protection Services-involved families: A randomized controlled trial. Child Maltreatment. doi: 10.1177/1077559518817678.