Wednesday, March 30, 2022


The IPHA Health News is proud to launch our spring edition with this scientific review on how expressing love for 'man's best friend' actually works as a measurable therapeutic activity.  Brought to you by our clinical and mental health researcher, Dr. Bobbi Kline, this unique feature explains the physiological response between our touching or connecting with a dog and a biometric reaction to our endocrine system.

Written by: Dr. Bobbi Kline

The relationship between dogs and humans began since the beginning of time when dogs looked to humans as a means of survival. Numerous studies have reported the significant benefits of pet ownership and interactive coexistence -  from stress reduction to social fulfilment to a healthier lifestyle.  Science is now providing insights into how this works, and the two hormones that are responsible: OXYTOCIN and CORTISOL.  A landmark study in 2015 revealed how dogs and their owners emotionally bond, and it’s related to the production of oxytocin – also known as the bonding hormone. When released, oxytocin creates a powerful social attachment between one person and another and creates that “feel good” sense of nurturing and closeness. [1]

It is known that a lengthy eye contact (or mutual gaze) forges a unqiue engagement between two individuals that somehow activates the release of our oxytocin, which also mediates a powerful emotional bond. One of the best-known examples of this is in the bond created between mother and infant. The oxytocin response is a feedback loop- a nurturing gaze from mom releases oxytocin in the infant, which stimulates production of oxytocin in the mother, then further stimulating nurturing behavior into a self-sustaining positive feedback loop. 

This study demonstrated that the same process happens when a dog and owner engage in the same behavior. For the first time, this oxytocin-mediated bonding has been shown to occur outside of intraspecies relationships.  A prolonged eye contact between dog-to-owner has shown to produce an oxytocin response in both the dog and the human owner. Unlike wolves, or even primates who are genetically closer to humans, dogs alone are able to elicit this oxytocin response loop. This may explain the extraordinary bonds formed between dogs and our human owners, and why puppies often exhibit similar behavior patterns as young children in response to visual cues. It may also explain why many dogs grieve when separated from their owners.

Oxytocin also has been shown to reduce stress and increase social reward behavior. But when people have SNPs or small errors in their genes involved in this pathway – including the receptor for the hormone oxytocin – they don’t always get the same level of benefit. [insert link to genetics vs genomics article]  Often they need more oxytocin than they get from a short interaction – something that can be challenging in today’s busy world. Perhaps this is one of the mechanisms behind the success of service dogs for people with disorders involving impaired social pathways, such as autism, PTSD, and other neurodevelopmental conditions where oxytocin is being used as an experimental treatment.

But it may not only be about oxytocin. More recent studies have added a second hormone into the equation: CORTISOL. [2] Known as the stress hormone, cortisol is released as part of the normal stress response. It is part of the “fight or flight” reaction that helps us flee from danger or hold our ground to confront it.  The challenge is that so often in our modern world, that stress response doesn’t go away when the threat does. Our brains and nervous system stay on high alert far longer than needed, resulting in chronic stress which wreaks havoc with our biology. 

While oxytocin is produced through the gaze, physical touch is the secret behind the stress-reducing power of dogs. When we hold or pet a dog, especially our own but this is not as critical an element as with the oxytocin, science has shown that cortisol levels go down. This, in turn, reduces the “fight or flight” stress response and gives us a chance to reset those alarm bells – and our biologic response. 

As with oxytocin, there are genes involved in the cortisol response that when they have these small errors, or SNPs,  can predispose a person to a heightened or prolonged stress response. This can be a significant reason to why the same experience that one person brushes off can lead to serious consequences in another – including anxiety, depression, PTSD, and even many chronic health issues thought to be purely physical – heart disease, obesity, autoimmune disease, and cancer just to name a few.

So when dog owner says they feel better around their dog, we now know why.  One can venture that a key reason behind the healing power of dogs is the combination of increasing the oxytocin response and reducing the cortisol-driven stress response. It’s science, it’s biology, and it’s their unconditional love that makes this partnership between dogs and humans so enduring.


(1) Nagasawa, M et al Oxytocin-gaze positive loop and the coevolution of human-dog bonds. Science 17 April 2015: Vol. 348 no. 6232

(2) Petersson M et al.  Oxytocin and Cortisol Levels in Dog Owners and Their Dogs Are Associated with Behavioral Patterns: An Exploratory Study

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