Part I: The Shared Nervous Symphony; How Dogs and Their Humans Heal Through their Vagus Nerves

By Erin Alefounder, Canine Rehabilitation Massage Practitioner — Soul Paws Massage & Wellness

The Silent Dialogue of Healing

Every day, when my hands meet a dog’s body, I feel a silent conversation unfold — one that doesn’t rely on words but on rhythm. The rhythm of breath. The subtle shifts in muscle tension. The warm, palpable trust that says, “I feel safe.”

This communication travels below language, rooted deep in our shared nervous systems. Humans and dogs both carry a vast, interconnected network of neural cells, glial cells, and sensory loops. At the centre of this conversation lies the vagus nerve — a wandering, un-myelinated superhighway that connects the brain, heart, lungs, and gut, tuning the body to a state of safety or survival.

This article is part 1 of 3 related articles that can be read in a different order but starting with part 1 will further provide a foundational understanding of how our bodies work to maintain homeostasis and how we strongly influence our health by keeping our parasympathetic nervous system activated. Then, we strongly influence our dog's health through co-regulation and activating their parasympathetic nervous system through targeted touch and smell.

Dogs have far more powerful tools to heal and regulate faster than humans -but only if their human guardian and the key guardians (ie. extended family, dog walkers, practitioners, etc) are on the same page! This article explores how the vagus nerve, glial cells, and sensory input — like scent and touch — shape our health, intuition, and the extraordinary healing connection between people and their dogs.

Not All “Brain Cells” Live in the Brain

We often picture the brain as a command centre. But in truth, the brain is a hub within a vast web of intelligent cells distributed throughout the body. These include neurons (neural cells) and their lesser-known, yet far more numerous counterparts: glial cells. In fact, approximately only 10% of the cells in the brain are neurons. The remaining 90% are glial cells — the “quiet gardeners” of the nervous system (Fields, 2009).

5 Types of Glial Cells and What They Do

Type of Glial Cell	Role	Analogy	Location
Astrocytes	Regulate blood flow, nutrients, neurotransmitter	“Neural baristas”	Brain, Spinal Cord & Vagus Nerve
Microglia	Immune cells that respond to injury/infection	“Cleanup crew”	Brain, Spinal Cord, Heart, Vagus Nerve, Lungs, Spleen & peripheral nerves
Oligodendrocytes/ Schwann cells	Insulate neurons with myelin for faster communication		CNS and Parasympathetic Nervous System which repairs/calms body
Enteric Glia	Support digestion, immunity, gut motility	“Gardeners of the gut”	Gut Lining, Enteric Nervous. System (ENS) & Vagus Nerve
Satellite Glia	Regulate peripheral sensory neurons	“Neighbourhood watch”	Peripheral ganglia

Illustration of glial brain cell types with rough location tags of where else they live beyond the brain.

The Body Has a Distributed Nervous System — And So Do Dogs

We often say, “trust your gut” or “my heart wasn’t in it.” These aren’t just metaphors. They’re biological truths. Both humans and dogs have neurons and glial cells in the heart and gut, capable of independent sensory processing and decision-making.

• The gut (enteric nervous system) contains ~600 million neurons (Pawolski & Schmidt, 2020).

• The heart houses ~40,000 intrinsic neurons, often referred to as the “heart brain” (Ottaviani & Macefield, 2022).

These peripheral “brains” communicate directly with the main brain via the vagus nerve, forming a triangle of gut–heart–head coherence — in both species.

Diagrams showing the “three brains” connected by the vagus nerve. The left image is showing a dog's "3 brain cell centres," the middle is a human equivalent and the right image shows the pathway of the vagus nerve in both species.

Meet the Vagus Nerve — Your Internal Peacekeeper

The vagus nerve (Latin: “wandering”) is the longest cranial nerve in the body, running from the brainstem through the neck and chest to nearly every major organ. Both dogs and humans have two pairs of 12 cranial nerves on each side of our heads. Our pairs of vagus nerves wander all the way from the brain to the lungs, the heart, and GI tract.

The brain is in the vagal loop, constantly listening and receiving info from the entire body. Approximately 80% of the vagus fibres carry sensory data from the body to the brain. This "data" includes your heart and breathing rate, your gut health, your stress hormones, and any inflammatory markers in your body, (Garis, G. et al., 2023). Then, based on that data received , it responds accordingly, helping the body get out of "fight or flight mode" and into "rest and digest" mode, (Breit, S, Kupferberg, A., Rogler, G. & Hasler, G. (2018). Healing, digestion and immune regulation simply cannot happen when your body is in a state of "fight or flight."

Occasionally being in a state of 'fight or flight' is not only a brilliant sympathetic nervous system response, it can often be a life saver! When your dog launches like a rocket to the other side of the house when the vacuum turns on, that's her sympathetic energy saving her from "death by Dyson." Or when your hound is half asleep on the sofa, but sees a raccoon scuttle by below the window, in 0.04 seconds he's vertical, paws on the window sill, eyes locked on target, ears and hackles up, and tail stiff. That's predator "adrenaline" fight mode in action.

Chronic fight or flight is when the life saving response becomes a serious threat to the body. It is why it is critical to stimulate the vagus nerve which literally governs our parasympathetic nervous system (PNS). The PNS is what helps our bodies rest, digest and heal. Humans and dogs have the same process going on! And even more cool than that, while I have researched 7 ways to stimulate the vagus nerve, specific massage techniques as well as holistic aromatherapy are two of the more powerful ones for dogs, and their humans.

Also, while you can tell a person how many seconds to breathe in/hold/breathe out or that it's actually positively consequential to your immune health write a gratitude journal, we cannot teach our dogs to do either of those things. This is why this article is focused on co-regulation between dogs and their main humans, as well as the importance of massage and holistic aroma/scent therapy.

When the vagus nerve is stimulated or "reset" it helps our bodies (both dogs and humans) in the following ways:

• Reduces cortisol, the main stress hormone, (Woody, A. et al., 2017)

  • (And don't forget that dogs have about 250,000 olfactory nerves compared to our 5K. and their double olfactory pathways ensure dogs inhale your cortisol, your dopamine and they essentially feel what you feel through their nose. More to come on this in Part II..)

• Stimulates the release of acetylcholine, which counters inflammation, (Tracey, K.J. 2002).

• Reduces heart rate and regulates heart rate variability HRV, (Bonaz, B., Sinniger, V. & Pellissier, S., 2016).

• Triggers the cholinergic anti-inflammatory pathway - essentially reducing our innate overactive immune responses, (Nephron, 13 (2) 79-83.

• Regulates digestion by communicating with the gut's microbiome and;

• Controls peristalsis; the muscle movements of intestines and;

• Regulates stomach acid, bile and the secretion of pancreatic enzyme secretion (Browning, K.N., et al., 2017)

When activated, the vagus triggers the parasympathetic nervous system — the “rest and digest” response — slowing the heart, relaxing the lungs, and promoting cellular repair (Caballero-Gallardo et al., 2025).

Dogs have an equally robust vagal system — and because of their heightened sensitivity to scent, touch, and breath, they often respond faster than we do.

The Vagus Nerve Talks with Glial Cells!

Glial cells in the gut and the vagal nerve help regulate neuroinflammation, transmit signals between nerves and immune cells, particularly natural killer (NK) cells, and regulate parsympathetic healing. When the vagus nerve is activated, glial cells help interpret and relay that signal locally in tissue. Microglia in particular work to clean up dead or damaged cells and remove them. This sounds like no big deal, but in so many ways, this is a big deal! A cancerous cell, for example, is often times a normal cell that became damaged. We therefore want lots of NK cells and healthy vagus nerves.

Massage, Touch, and the Vagal Loop

When you touch a dog with presence and intention, you’re not just soothing muscles. You’re activating C-tactile fibres — slow-conducting nerve fibres linked to emotional regulation and vagal tone (Walker et al., 2017).

Massage enhances:

• Heart Rate Variability (HRV)

• Parasympathetic tone

• Oxytocin release

• Gut and immune function

It also quiets glial inflammation, helping the nervous system reset. That’s why dogs (and humans) often sigh, yawn, or even fall asleep mid-session.

This effect is mutual. As the practitioner regulates your own breath and nervous system, your dog’s body follows. This is co-regulation — biology’s way of syncing nervous systems through breath, touch, and scent.

Final Thoughts: The Nervous System is a Garden

Neurons may be the communicators, but it’s the glial cells that care for the garden. When inflammation, trauma, or stress overwhelm the system, that garden becomes parched.

With scent, touch, and a calm presence, you water the nervous system back to life. Your dog feels it. You feel it. And the vagus nerve becomes the conductor of that healing music once again.

What’s Next: From the Vagus to the Senses — and Beyond

As we’ve explored, the vagus nerve is the unspoken bridge between safety and healing in both humans and dogs. But this is only the beginning of the nervous system’s silent symphony. In Part II, we’ll travel deeper into the senses — especially smell — to uncover how aromatherapy, through the olfactory–limbic–vagal pathway, unlocks intuition and co-regulation. You’ll discover why dogs “feel” scent differently, how shared aromas can align emotional states, and what this means for your bond, breath, and biological rhythms.

Then in Part III, we’ll bring it all home with a practical exploration of immune system regulation, chronic stress relief, and multimodal healing — from massage and infrared therapy to CBD, adaptogenic support, and vagus-stimulating touch techniques. You’ll learn how these tools create lasting change at the nervous system level — not just in theory, but in touch, smell, and experience.

Sources:

• Bonaz, B., Sinniger, V. & Pellissier, S., (2016) The Journal of Physiology, 594 (20), 5781-5790.

• Browning, K.N., Verheijden, S., & Boeckxstaens, G.E., (2017). Gastroenterology, 152(4), 730-744. https://www.sciencedirect.com/science/article/pii/S0016508516354877

• Caballero-Gallardo, K., et al. (2025). Vagus nerve and anti-inflammatory reflex in chronic stress. Neuroscience Journal.

• Fields, R. D. (2009). The Other Brain: From Dementia to Schizophrenia. Simon & Schuster.

• Ottaviani, M. M., &; Macefield, V. G. (2022). Cardiac afferents and the emotional brain: A Physiology Review.

• Pawolski, V. & Schmidt, T. (2020). Neuroimmune communication in the enteric nervous system. Frontiers in Cellular Neuroscience.

• Silver, R. J. (2019). Medical Marijuana and Your Pet: The Definitive Guide.

• Tracey, K.J. (2002). Introduces the concept of the 'inflammatory reflex' in Nature, 420 (6917), 853-859. https://doi.org/10.1038/nature01321

• Woody, A., Figueroa, W.S., & Benencia, F. (2017) Bioscience and Medicine, 3 (4), 142-151).

• Zou, S., & Kumar, U. (2018). Cannabinoid receptors and the endocannabinoid system: Signaling and function in the central nervous system. International Journal of Molecular Sciences.