A study published in 2017 has begun to give some credence and ask some interesting questions about chronic stress or depression in our horses. According to Jodi Pawluski and team(1) a group of horses showing signs of compromised welfare (living conditions fostering social restrictions, limited space and interactions with inexperienced riders) showed abnormally low cortisol levels.
Cortisol, aka ‘the stress hormone’ is one useful indicator of the way the horses Autonomic Nervous System (ANS) is working. The ANS is a largely unconscious mechanism which regulates bodily functions such as the heart rate, digestion, respiratory rate, pupillary response, urination, and sexual arousal. It is also involved in controlling blood sugar levels, regulating metabolism, helping to reduce inflammation, and assisting with memory function. It has two complimentary sides – the Sympathetic “flight/fight”and the Parasympathetic – “rest/digest”. When there is a balance these work nicely together to maintain homeostasis – a happy balance. Sympathetic stimulation acts to increase the blood pressure, heart rate, respiratory rate, blood sugar levels and muscular tension. All these are characteristic of the sympathetic nervous system driven “flight/fight” reaction so commonly seen both humans and animals. Elevated cortisol is one marker of Sympathetic activity. On the flip side, insufficient or suppressed levels of cortisol, as can occur when stress is chronic, reduces all these functions. One may think ‘Great! The opposite of flight/fight is rest/digest. That’s good, right?’, but unfortunately this isn’t the case. When cortisol levels become abnormally low, the body is on an almost constant ‘go slow’, with symptoms including fatigue, muscle weakness, lack of motivation or drive, an inability to cope with stress and depression. Neither state is conducive to a happy, enthusiastic individual, whether horse or human.
Further studies are obviously needed to help drill down into the relative influence of common management practices when it comes to our horses, though without a doubt the more a horse can live like a grazing herd animal and be handled by knowledgeable and gentle handlers, the better. In reality there are many things which limit this ideal situation, and we as horse owners have a duty of care to try to mitigate the effects our environment and interactions have on our horses. For many the idea that Osteopathy can help to do this might be a new one. Many studies and much clinical evidence exists to support the idea that Osteopaths can play a significant role in helping to restore balance to the ANS function of our horses.
Recently I’ve had the pleasure of working with a thoroughbred mare who has had what can only be described as more than her fair share of stressful experiences in her life. Being used as a surrogate for several years, and being a highly sensitive mare, she has developed a strong fight response to the sensation of being confined. This likely relates to being handled within a crush and coming to associate pressure against her sides or hindquarters as a stressful and threatening thing. This, of course, makes closing her into a horse float a highly charged event. Her owner has been working patiently with her, doing regular training to help desensitise her to touch on her sides and hindquarters as well as to teach her the float is a safe environment and has got her to the stage where she self loads, however as soon as she feels the divider or ramp come up she begins double barrelling and swinging her hind end from side to side to the point of inflicting wounds on herself. This naturally only serves to reinforce her inherent stress response and belief that confinement is dangerous. In general, she was noted to be an aloof and non-affectionate mare who displayed many stress responses both in handling and in the paddock. When ridden she works and is quite relaxed and happy, however would never mouth the bit and regardless how much suppling work was done would never display a single drop of saliva at the lips.
Our initial treatment involved working through the ribcage to encourage freedom of motion at the costovertebral joints all the way to the thoracolumbar junction to effect the adrenals sympathetic ganglion as well as to encourage full function of the diaphragm during respiration. She was found to be a very shallow breather and the ribcage as a whole was quite immobile. Human studies have shown significant effects of osteopathic techniques on stress hormones, one in particular using a technique known as Rib Raising (2). This technique addresses the costovertebral joints through the length of the ribcage and is clinically well known to be a powerful way of helping balance the autonomic nervous system due to the anatomical link to the sympathetic ganglia. Further work was done to put a calming stimulus into the sacrum, which is also associated with the sympathetics. Again, the sympathetic side of the autonomic nervous system is the one which drives the fight/flight response.
The parasympathetics, drive the “rest and digest” functions. This is the calm and relaxed state of affairs. Structurally this is in part composed of cranial nerves that supply the face, cardiovascular system, respiratory system and gastrointestinal system. Parasympathetic function can be readily supported by allowing the jaw and diaphragm to function optimally. By encouraging full diaphragmatic function with simple exercises, it is possible to also give the vagus nerve a nice bit of stimulation. In the image below we are looking at numbers 3, 15 and 16, so you can see how far reaching work around the jaw and poll can be and how the diaphragm (which divides the thorax from the abdomen) may stimulate parasympathetic function via the vagus nerve.
Immediately after the first treatment the mare was noted to be far more calm than usual, quietly wandering around the small yard we were working on another horse in, picking at grass. This was noted by the owner to be quite unusual behaviour for a mare who was usually on guard around other horses and tended to pace the fence line if not in her own paddock. I left the owner with several easy exercises to do daily to help keep the autonomic nervous system more balanced. Over the next week I was pleased to receive several updates saying how relaxed the mare had become, a total change in character. The next visit we decided to push our luck a little and give her her treatment standing next to the horse float, a space she would usually become anxious and on edge. Initially obviously nervous we quietly worked through similar areas, noting a big improvement in passive range of motion and tissue tension around the ribcage as well as a greater capacity for diaphragmatic breathing. The owner was again pleased to see the mare calm and relaxed and picking grass while standing next to her least favourite piece of metal.
Our next plan is to work towards adding more stimulus by opening the tail gate and potentially eventually treating her or doing daily exercises to flick her nervous system into ‘rest and digest’ while standing on the horse float. It may take a while to retrain her nervous system that this is not a threatening situation which requires a fight response, however initial changes have been very positive and have reaffirmed how powerful Osteopathic treatment can be for modulating this crucial part of our nervous system.
For those interested in more reading about how Osteopathic treatment can help us (and presumably our horses) towards a less stressed and more healthy state, I have attached are some extra references for studies (2, 3 & 4) which also have shown preliminary findings of positive effects of various Osteopathic technniques on the autonomic nervous system in both relaxed and stressed humans, measuring indicators for sympathovagal function at heart level, cortisol levels and immune function.
It is a fascinating aspect of Osteopathic practice which I always enjoy seeing results from. As with all natural approaches, results will vary and een after 15 years of practice i’m still often surprised by how much change can be achieved, and in ways I wasn’t necessarily anticipating. The main principle of Osteopathy is that if the tissues in the body are moving and functioning to the best of their ability then that body will head towards homeostasis (a happy healthy balance), and the path that takes is sometimes a little unpredictable but with time and patience it’s a rare case where we can’t help the horse achieve that balance in their system.
Update – After posting this, I received a call from the mare in questions owner. She was thrilled to report she had spent an afternoon during the week playing with the mare around the whole travelling in the float issue. She began with groundwork exercises to calm the mares nervous system as prescribed. Then as she was going so well progressed to loading her, letting her stand, bringing the divider across, again waiting, bringing up the tail gate and the final test a slow drive around the block. The mare maintained her composure the entire time besides one small kick out when actually moving. Upon return she stood calmly for another 5 minutes with the tail gate down and waited for the cue to back off. Naturally the owner is absolutely thrilled to be approaching the stage she can again contemplate taking her lovely horse out again! I’m also thrilled to see the changes 2 treatments have brought to this lovely mare’s general day to day anxiety levels. Stay tuned and I’ll add more updates as they come to hand.
1 – Pawluski, J., Jego, P., Henry, S., Bruchet, A., Palme, R., Coste, C., Hausberger. M. Low plasma cortisol and fecal cortisol metabolite measures as indicators of compromised welfare in domestic horses (Equus caballus). PLOS ONE, 2017; 12 (9): e0182257 DOI: 10.1371/journal.pone.0182257
2 – Henderson, A.T., OMS III; Fisher, J.F., OMS III; Blair, J., OMS I; Shea, C., OMS III; Li, T.S., DO; Grove Bridges, K., PhD. Effects of Rib Raising on the Autonomic Nervous System: A Pilot Study Using Noninvasive Biomarkers. The Journal of the American Osteopathic Association, June 2010, Vol. 110, 324-330.
(Twenty-three participants were recruited, of whom 14 completed the study (7 in each group). Subjects who received rib raising had a statistically significant decrease in α-amylase activity both immediately after (P=.014) and 10 minutes after (P=.008) the procedure. A statistically significant change in α-amylase activity was not seen in the placebo group at either time point. Changes in salivary cortisol levels and flow rate were not statistically significant in either group.
Conclusions: The results of the present pilot study suggest that SNS activity may decrease immediately after rib raising, but the hypothalamic-pituitary-adrenal axis and parasympathetic activity are not altered by this technique. Salivary α-amylase may be a useful biomarker for investigating manipulative treatments targeting the SNS. Additional studies with a greater number of subjects are needed to expand on these results.)
3 – Fornari, M. DO (Italy); Carnevali, L. PhD; Sgoifo, A. PhD. Single Osteopathic Manipulative Therapy Session Dampens Acute Autonomic and Neuroendocrine Responses to Mental Stress in Healthy Male Participants. The Journal of the American Osteopathic Association, September 2017, Vol. 117, 559-567. doi:10.7556/jaoa.2017.110
(Conclusion: The application of a single OMTh session to healthy participants induced a faster recovery of heart rate and sympathovagal balance after an acute mental stressor by substantially dampening parasympathetic withdrawal and sympathetic prevalence. The OMTh session also prevented the typical increase in cortisol levels observed immediately after a brief mental challenge.)
4 – Saggio, G., DO; Docimo, S., DO; Pilc, J., DO; Norton, J., DO, RN; Gilliar, W., DO. Impact of Osteopathic Manipulative Treatment on Secretory Immunoglobulin A Levels in a Stressed Population. The Journal of the American Osteopathic Association, March 2011, Vol. 111, 143-147.