Two Different Vagus Nerve Responses To Longterm Trauma In Horses And How The Trust Technique Is Helping Both Horses To Re-regulate Their Nervous Systems

Young horses at REIN Rescue, who have been recently halter trained, demonstrating excellent social engagement. This means that the ventral vagal nervous system is strongly online, as will be explained further in this article.

Right now, I am treating two horses who have experienced significant long-term trauma in their past. Both horses have responded differently to their trauma, so I thought it would be interesting and informative to try to explain what is going on in the autonomic nervous system with these two different cases using Dr. Stephan Porges’s polyvagle theory as a starting point in which we think of the autonomic nervous system response to stimuli (animals, including humans, objects and situations) as affecting three separate branches of the autonomic nervous system.
The autonomic nervous system controls involuntary bodily reactions to stimuli (including heart rate, blood pressure, organ responses, muscle contraction, etc). It is made up of three separate branches of the vagus nerve. The ventral vagal system controls feelings of emotional safety and safe emotional connections to others. The dorsal vagal controls sleep, rest, relaxation, and digestion at the lower levels, as well as immobilization, numbing, and shutdown at the upper levels when situations become overwhelming. Both the ventral and dorsal vagus nerves make up the parasympathetic response.

The sympathetic branch stands alone and controls bodily and involuntary responses to danger, stress (fight, flight  or freeze), and excitement (any alert action responses, including play and sex). It can be thought of as the energy level control for excitement and the fight/flight, or freeze response to danger.

This diagram shows the autonomic nervous system choices that present during a perceived threat. Flight, Fight or Freeze on the sympathetic branch and collapse on the parasympathetic when the animal can find no other response to self preservation.

We can think of these separate branches of the vagus nerve as being three dials. The first dial is the "ventral vagal dial," "seeking friendship and connection dial." It runs from a low of zero, avoidance, to ten, super friendly. The next is the "dorsal vagal dial," which runs from zero, asleep, relaxing, digesting to 10, complete shutdown/ knocked out. The "sympathetic dial" controls the level of excitement or fight or flight response necessary to keep safe from danger or engage in sex or play. It runs from a zero of not engaged at all as the animal is in rest/digest parasympathetic state to a full 10, all power on, to fight hard or run fast.

Each individual mammal, including humans, will have a regular dominance pattern, a typical signature where these dials will be set more or less on a regular day. For example, a well-raised horse with just the right amount of exercise, food, and friendship, low stress, and no history of baggage from the past will have a high setting on the social engagement dial (ventral vagal), a dorsal vagal setting between 0 when he is asleep and 7 when he is engaged in play with another horse, and a sympathetic setting between 0 and 7 depending if he is sleeping, resting, eating or playing.

This diagram show more or less where the 3 autonomic nervous system dials would be in a well regulated, unstressed horse. They, of course, vary somewhat with activity.

In contrast, if a Mustang was chased at high speed (flight response) by a bunch of motorcycles into a corral and then got stuck in a metal panel as he tried to jump out while six cowboys with ropes were moving in on him, and he passed out (collapse state) due to fear; he would have his ventral vagal dial at 0, his dorsal vagal dial at 10, and his sympathetic dial also at 10, but as he slid further into collapse, the sympathetic dial would fall fast, as his heart rate slowed, his muscles relaxed, and his digestive tract and other organs let loose. But, as this Mustang came to, he would have his ventral vagal dial still off (at 0), his dorsal vagal falling back towards 5 or 6 from 10, and his sympathetic dial cranked up to 10 again. They come out of the collapse response as they went in. This is important to note when working and treating shutdown cases where the horse has used the dorsal vagal branch of the nervous system to respond to stress.

This diagram shows where the 3 different branches of the autonomic nervous system will be in a highly distressed horse undergoing a traumatic event.

If a horse or any other social mammal feels unsafe for a long period, it will go into a shutdown mode of operation as a way to cope. These coping mechanisms can look quite different from one individual to the next in terms of where their autonomic nervous system dials will be predominately set and how they will react when they are triggered. Below, I discuss two horses' very different responses to traumatic pasts and how, in each case, the Trust Technique is being used to help them each re-regulate their nervous systems to a more balanced response to stimuli.

Ali

Ali demonstrating his hyper-vigilant, sympathetically dominant state.

Ali, a big, beautiful, bay Frisian/Arab sport horse, lived a sheltered life. He was born and raised to the age of six on the same farm. He did not get to spend much, if any, time outdoors in a pasture, getting used to stimuli. He was kept in a stall and let out in an indoor arena. When his owners wanted to show him in halter classes, he was given sedatives. One day, he was sold, put on a trailer, shipped to a farm for three months of training, and then shipped to his current home.
This scenario of an underexposed nervous system during his development, the solo shipping experience, the arrival in totally alien environments, and no familiar companions to help him co-regulate his nervous system blew Ali's mind, and he became overwhelmed. He grew tense and hyper-vigilant, unable to eat well or sleep. Over time, he developed a sympathetically dominated nervous system in which he was almost constantly in a state of hypervigilance.

Ali has spent so much time in a hyper-vigilant (sympathetic-dominated) state that his muscles have contracted a lot, and his facia has pulled tight around his body. His right shoulder is thrust forward. He has dents in his neck and muzzle, and his eyes do not blink as often as they should. Sometimes, his face appears to be frozen. He does not feel that hungry as his stomach muscles are also contracted. These symptoms are all in line with Ali's nervous system being in a sympathetically dominated pattern. Sometimes, he comes out of a high neck, wide-eyed, disassociated stare, and he blinks, lowers his head, and becomes friendly. Still, he is always ready at the slightest noise or quick movement to freeze again or to bolt if the opportunity permits.

Ali's dials would look as follows. The ventral vagal dial, social engagement, would be flickering between zero when he is taken over by the frozen sympathetic (fear) or bolting (flight) response and about an 8 when he comes back to himself and the present moment for a nice scratch and to socially engage with his new horse and human friends. Ali's underlying personality is a friendly and curious one. His dorsal vagal is mostly offline (dominated by his sympathetic state), except when his neroception (feeling) of his environment allows him to socialize, rest and sleep briefly or when we are helping him with the Trust Technique which can encourage the rest/digest part of the dorsal vagal response.

Diagram showing Ali's autonomic nervous system dominance pattern. Ali due to his past trauma is caught in a sympathetically dominated nervous system pattern. He is a hyper-vigilant horse.

Since Ali is hyper-vigilant and dominated by a sympathetic pattern of his nervous system, the Trust Technique helps Ali by allowing him to co-regulate his nervous system with a being who can keep their nervous system grounded by the present moment. The present moment is an authentic space in the here and now where nothing bad or dangerous or exciting is happening. Present moment focus stimulates the rest/digest part of the dorsal vagal dial to increase (parasympathetic).

The Trust Technique also helps by providing a feeling and listening tool as well as a space that allows the animal to let go of past trauma and worry about things in their environment that are making them feel unsafe or unpeaceful. By regarding all the animal's concerns and responding so that they feel felt, seen, and understood, the animal can start to process past trauma and also down-regulate their nervous system enough to be able to form new opinions about their current level of safety (learning state). When an animal is fully in a highly sympathetic state, they can not learn anything new.

The Trust Technique practitioner oscillates between their grounded state in the present moment and the regarding state where they are matching the animal's nervous system as is needed to help guide the animal's nervous system to a more regulated state.

In Ali's current case, where he is flickering in and out of a high sympathetic dominated state, just doing daily, or twice daily 30-40 min sessions of holding a present moment space and regarding him when his thinking levels are rising instead of falling, is what is needed most until he stays longer in the present moment without checking out in a freeze state. This work should be done, at first, in the least stimulated environment possible, a place that he already knows and finds safer than anywhere else.

Having regular stablemates also helps Ali a lot, as he can also co-regulate off of them as they are older and calmer and have been peacefully living at their current address for a long time. Over time, Ali will revert to this freeze/flight state less and less as the rest/digest end of the dorsal vagal system comes back online more and more, and he can constantly re-evaluate his safety. This will turn up his social engagement dial as well, and Ali will be able to cue off the horses and humans around him that he is safe. Once this happens, triggers that still cause Ali to freeze can be dealt with specifically using the same Trust Technique tools.

In the two months I have been working with Ali and his owner, the Trust Technique has already been able to help him eat better and get more rest. He holds his head up high less often, and the frozen look overtakes his kind expressions less and less. In general, his face is more expressive, and his body is less constricted by fear. His owner sees a big change in his day-to-day level of calmness. Ali's rest/digest low end of the parasympathetic branch is coming back online and gaining more space in his way of being.

Tocumen

Tocumen does not show the same level of hyper-vigilance that Ali does but he can still quickly flip into a high, sympathetically dominated state when he is triggered by an action or something in his environment.

Tocumen is a beautiful, dapple-gray Andalusian who was bred and raised for upper-level dressage in Spain. He was trained too quickly through the levels of dressage, had a late and painful gelding, was put on transport before he had healed from the gelding surgery, and had a lengthy shipping and quarantine into the USA. When he finally arrived at his current farm, his mind was a mess, and his new owner, who is an equine chiropractic vet, said he seemed to have the signs of PTSD.

Joy, Tocumen's owner, has spent the last three years doing everything she could think of to help him. She said that when she first started riding him again, he would freeze like there was some stop button she did not know about. She said that while he has come a long way in three years and is finally fairly social again and in control of himself most of the time, he can still sometimes come unglued in forceful and dangerous ways, panicking or bolting out of seemingly nowhere.

Tocumen's ventral vagal social engagement dial is still set a little low, though it has drastically improved from when he arrived at Joy's farm. His rest/digest dial stays between 1, a resting state, as he probably no longer allows himself to sleep deeply, and 5-7, an alert state of interaction (taken over by the sympathetic branch). However, it would not surprise me that during his whole ordeal, he may have almost gone into a collapse (high dorsal vagal response) mode at one point as the stress from the surgery and the shipping overwhelmed his nervous system.

Sometimes, when a stimulus like a human approaching with a halter becomes a little too strong, his social dial descends as he starts to avoid the approaching human. When some action, object, or situation triggers his nervous system, he can fly into a highly sympathetic state and lose all his social engagement motivation. In this state, he can not reason or make new associations. He loses his sense of reality in these moments and panics.

A diagram of Tocumen's autonomic nervous system dials. If triggered by something, Tocumen can go to a 10 on his sympathetic dial, when this happens his social engagement dial zeros out and he can not engage or even hear the human trying to help him out of his crisis.

The Trust Technique can be used to help Tocumen. First, a daily practice in a quiet space will help to bring his rest and digest part of his parasympathetic response back on line. As his parasympathetic rest/digest system gains a larger dominance (spending more time in a relaxed state), he will be able to take more in, and his nervous system and mind will become more aware that he is no longer under threat.

Also crucial in Tocumen's case will be to identify as many of his triggers as possible and slowly use the tools of the Trust Technique to help him clear them all. For example, we noticed that one of his triggers was approaching and putting his halter on. To fix it we stopped at the first sign of his social engagement dial decreasing, as he started to avoid our approach with the halter. We stopped and got present for a moment. We then regarded him until he was again wanting to engage with us. We kept approaching until he again started to show concern. We stopped. We got present. We regarded. We waited for more engagement from him (increase on the ventral vagal dial, decrease on the sympathetic dial, decrease towards rest and digest on the dorsal vagal dial), and we continued.

Now, Tocumen puts his head voluntarily in the halter when he sees it. This happened because we watched his dials carefully and responded while staying grounded in the present moment. Tocumen was able to process a new association with his halter and being haltered. Tocumen is making great progress with the Trust Technique. He is now a little calmer overall, not allowing as many things to trigger him. He now volunteers to put his head not only in his halter but also his bridal, where once both these things triggered him. He also comes down quicker from things that do trigger him (decrease in the sympathetic dial, decrease on the rest/digest branch of the dorsal vagal dial towards more relaxation, and an increase in the social engagement dial where it is easier for him to engage, learn new things and make new associations with past fears.)

The Trust Technique provides a wonderful tool to help horses process trauma and make new associations where once bad memories kept them traumatized. It does this by listening to the horse on a profound level. This article has provided you with a little under-the-hood look at what the horse's autonomic nervous system is telling you and how to respond to this information in a way to help them process past trauma.

If you are interested in helping a horse in your care out of trauma with the Trust Technique, you can find me at my website: https://www.consideringanimals.com/the-trust-technique.html .
I offer both in-person (Western NC) appointments and Zoom. You can also look up the Trust Technique Headquarters, where you can download the free Messages Of Trust Video: https://trust-technique.com/product/messages-of-trust/tt/316/