What Is the Vagus Nerve & Why It Matters The vagus nerve is a major cranial nerve that links the brain with many body systems — heart, lungs, digestion, etc. A well-functioning vagus nerve supports the “rest & digest” (parasympathetic) nervous system, helping the dog calm down, regulate stress, recover more quickly. If vagal tone is low (nerve not well stimulated) or there’s tension/pain, the body may stay in a heightened “fight or flight” state, which increases anxiety, affects digestion, sleep, behavior. When to Consider Using Vagus Nerve Massage After a stressful event (visitors, car ride, grooming, loud noises) When the dog seems unable to “settle down” (restless, pacing, alert) As part of a daily routine to improve relaxation and emotional regulation When you notice signs that might be tied to nervous system overactivation: shallow breathing, racing heart, anxiety behaviors, poor digestion, etc.