Sentinel Trauma is a one-time learning event which can leave a permanent imprint on the autonomic nervous system.
According to Dr. Stephen Porges, Sentinel Trauma is a single overwhelming event which the body-brain registers as life-threatening. This could be an accident, an assault, or a medical crisis.
It is an "one-trial imprint" which results is the sudden re-calibration of autonomic state and neuroception.
Sentinel Trauma is distinct from chronic stress and complex trauma. It is also separate from fear conditioning, which requires repetition. Sentinel Trauma, like Conditioned Taste Aversion, is a one-trial learning event which is highly resistant to extinction. It's function is a survival imprint for life threat, embodied as autonomic state.
This autonomic rewiring is initially adaptive, but can become metabolically costly when the defensive imprint becomes chronic rigidity. Previously neutral cues are now seen as threats and elicit high levels of reactivity. There is often dissociation, shut-down, or panic without clear cause.
If your dog seems to be in a chronic state of defensiveness and reactivity, and has lost their autonomic flexibility, he or she may have experienced a sentinel trauma. They may have an autonomic survival imprint which is locked into the brainstem, and the reactivation of this implicit memory is INVOLUNTARY. This means that your dog is unable to control their behavior at this point because the cortex is being completely bypassed. This is why we have to look at behavior WITHOUT intentionality.
*Source: The Polyvagal Institute conference, Dr. Stephen Porges' presentation on Sentinel Trauma
https://www.polyvagalinstitute.org/2025gathering
Photo Credit: Photo by Samuell Morgenstern on Unsplash