One Medicine evolved into One Health in 2004, integrating human medicine, veterinary medicine, and environmental sciences. One priority is preventing the emergence and spread of zoonoses—diseases that spread from animals to people—to protect human health.

Zooeyia provides the philosophical construct of the human-animal bond’’ (p. 190).

The human–animal bond is ‘‘a mutually beneficial and dynamic relationship between people and animals that is influenced by behaviours that are essential to the health and wellbeing of both. This includes, but is not limited to, emotional, psychological, and physical interactions of people, animals, and the environment’’. The strength of this bond and its potential implications for human health and wellness are the fundamental premise of AAIs.

Wilson EO (1984) Biophilia, Cambridge, MA: Harvard University Press Zinsstag

Kahn P (1997) Developmental psychology and the biophilia hypothesis: Children’s affiliation with nature. Developmental Review 17:1–61

Kamioka H, Okada S, Tsutani K, Park H, Okuizumi H, Handa S, Oshio T, Park SJ, Kitayuguchi J, Abe T, Honda T, Mutoh Y (2014) Effectiveness of animal-assisted therapy: a systemic review of randomized controlled trials. Complementary Therapies in Medicine 22:371–390

Katcher AIn: Beck A (editors) (1987) New Perspectives on Our Lives with Companion Animals, Philadelphia, PA: University of Pennsylvania Press

Kellert S, Wilson EO (1993) The Biophilia Hypothesis, Washington, DC: Island Press

Hanrahan C (2014) Integrative health thinking and the one health concept: Is social work all for ‘one’ or ‘one’ for all?. In: Animals in Social Work: Why and How They Matter, Ryan T (editor), New York, NY: Palgrave Macmillan, pp 32–45

J, Schelling E, Waltner-Toews D, Tanner M (2011) From ‘‘one medicine’’ to ‘‘one health’’ and systematic approaches to health and well-being. Preventative Veterinary Medicine 101:148–151

Maujean A, Pepping C, Kendall E (2015) A systematic review of randomized control trials of animal-assisted therapy on psychosocial outcomes. Anthrozoos 28:23–36

Melson G (2008) Children in the living world: Why animals matter for children’s development. In: Human Development in the 21st Century: Visionary Ideas from Systems Scientists, Fogel A, King B, Shanker S (editors), New York, NY: Cambridge University Press, pp 147–154

Miller S, Kennedy C, DeVoe D, Hickey M, Nelson T, Kogan L (2009) An examination of changes in oxytocin levels in men and women before and after interaction with a bonded dog. Anthrozoos 22:31–42

Natterson-Horowitz B, Bowers K (2013) Zoobiquity: The Astonishing Connection Between Human and Animal Health, New York, NY: Vintage Books

Nebbe L (2000) Nature therapy. In: Handbook on Animal-Assisted Therapy: Theoretical Foundations and Guidelines for Practice, Fine A (editor), San Diego, CA: Academic Press

For example, those faced with ills, mental health or addictions, need to effectively re-integrate within the ecologies of their families and society at-large.

In AAIs, the animals themselves are the health intervention. They enhance positive feelings in people, raise oxytocin levels, encourage clients out of emotional numbness, and foster trusting and non-judgmental relationships (Miller et al. 2009; Palley et al. 2010; Burger et al. 2011; Handlin et al. 2011; Anson 2014). An understanding of how this occurs must acknowledge and appreciate the animals’ contribution to both sociality and the emergence of new and dynamic social environments.

Highly industrialized and technology-driven societies increasingly disconnect people from nature.

This split can have a negative effect on mental, physical, and spiritual health. A connection with other living organisms (‘‘biophilia’’) is considered a fundamental, biological human need (Wilson 1984; Kellert and Wilson 1993; Kahn 1997). Companion animals are a connection to the natural world. The human–animal interaction is a potential space for human healing, specifically attending to the split between nature and the human spirit (Katcher and Beck 1987; Berry 1990; Nebbe 2000; Melson 2008).

Relationships with pets, the closest of all human–animal relations (Franklin 1999), may fulfill this biophilic need. Deep bonds between therapy animals and people have been likewise documented in AAIs (Dell et al. 2011; Hanrahan 2013).

The One Health concept focusses on the interface of humans, animals, and the environment, and how each affects health. Applying this framework to AAIs permits focused reflection on how AAIs contribute to human wellbeing, on the welfare of the animal, and on the environment. The significance of this interface arose in the consideration of the wellbeing of animals, people, and the environment in equal measure.

the mutual interactions of humans (beneficiaries), animals (facilitators), and the environment (program content/context) contribute to the wellbeing (Adams et al. 2015).

Acknowledgement of the equal interdependence of humans, animals, and the environment (Papequash Elder 2011; Honouring Our Strengths 2014).

the relations among all equivalent beings of Creation—humans, animals, and the environment.

Some recent interpretations of One Health support this egalitarian consideration of the health of all three elements (Natterson-Horowitz and Bowers 2013; University of Saskatchewan 2014). However, others critique the One Health concept as inherently anthropocentric, cogently arguing that human health benefits first from this approach, and raising concerns about the implications for the environment and all its inhabitants (Hanrahan 2014).

The One Health concept is not the first attempt to account for the animal–human–environment interface. Some synergy is also found with non-Western understandings, including Indigenous worldviews.