| HEADSHAKING |
Headshaking syndrome is caused by Adrenal Dysfunction. (The physical
inability to cope with stress in any form)
The following information has been compiled from many years of diagnosing & treating headshaking
horses, together with studies at degree level in Oriental Medicine,Western physiology/bio-chemistry,anatomy
& pathology. Annabelle Knight
The Adrenal glands are 2 small pea shaped endocrine glands located on the
top of each kidney.
Each gland is divided into an outer cortex & an inner medulla.
They each secrete different hormones, the cortex hormones being essential to
life but the medulla hormones not so essential.
The Adrenal Cortex is divided into 3 zones, each of which secretes different
hormones.
• Zona Glomerulosa secretes MINERALCORTICOIDS of which
Aldosterone is the major hormone. It regulates homeostasis of the
2 mineral ions, Sodium (Na+) and Potassium (K+). It also promotes
secretion of H+ in the urine to help prevent acidosis.
The Renin-angiotensin-aldosterone pathway controls secretion of Aldosterone i
n response to blood volume-blood pressure levels.
• Zona Reticularis produces a small amount of weak androgens – steroid hormones that have
masculinizing effects
• Zona Fasciculata secretes mainly GLUCOCORTICOIDS, so named because they affect the glucose
homeostasis as well as regulating metabolism and
resistance to stress. 95% of these hormones are comprised of Cortisol.
Control of cortisol is via a negative feedback system. Low blood levels stimulate cells in the hypothalamus to
secrete CRH (corticotropin-releasing hormone). CRH (together with a low level of cortisol) promotes the
release of ACTH (Adrenocorticotropic hormone) from the anterior pituitary which flows in the blood to the
adrenal cortex where it stimulates glucocorticoid production.
Under normal circumstances, GLUCOCORTICOIDS have the
following functions;
• Protein breakdown.
They increase the rate of protein breakdown, particularly in the
muscle fibers thereby liberating amino acids into the bloodstream for
the synthesis of new proteins or ATP production.
• Glucose formation
They stimulate liver cells to convert certain amino or lactic acids to
glucose for use as ATP production (gluconeogenesis) The body's
most important energy source.
• Lypolysis
They breakdown triglycerides & release of fatty acids from adipose
tissue into the blood.
• Anti-inflammatory effects.
They inhibit white blood cells thereby dampening the inflammatory response. They also retard tissue repair
& as a result slow down wound healing.
• Depression of immune responses.
Interleukin-1 is secreted by the macrophages of the immune system. One action of this is to stimulate
production of ACTH which in turn stimulates production of cortisol to provide resistance to stress and
inflammation. In turn cortisol suppresses further production of Interleukin-1 so switching off this immune
system mediator.
• Resistance to stress
They work in many ways to provide resistance to stress. The additional glucose provided by the liver cells
provides tissues with a ready source of ATP energy to combat a range of stresses including exercise,
fasting, fright, temperature extremes, high altitude, bleeding, surgery, trauma & disease. They also make
blood vessels more sensitive to other hormones that cause vasoconstriction, therefore raising blood
pressure. This would be an advantage in severe blood loss which causes blood pressure to drop.
The Adrenal Medulla is a modified sympathetic ganglion of the ANS & has the ability to quickly release the
hormones epinephrine & norepinephrine (formerly adrenaline & noradrenaline) in response to a stressor.
These greatly augment the flight/flight response by
• Increasing output of the heart.
• Increasing blood flow to the liver, heart, skeletal muscles & adipose tissue.
• Dilate airways to lungs
• Increase blood levels of glucose & fatty acids.
The Stress Response
We live in a world that is constantly bombarding us with every type of stress. Some stress (eustress)
prepares us to meet certain challenges & is therefore helpful. Other stress (distress) is harmful. A stressor
may be almost any disturbance of the body – heat, cold, environmental poisons, heavy bleeding, drugs, or
any strong emotional reaction or event.
The body’s natural homeostatic mechanisms attempt to counteract stress & when they are successful, the
internal environment remains within the physiological parameters.
However if he stress is extreme, unusual or chronic these normal mechanisms may not be enough. This is
when the body starts to undergo changes that compromise health & wellbeing. These changes, called the
stress response, or general adaptation syndrome, are controlled mainly by the hypothalamus & occur in 3
stages as discovered by Hans Selye in 1936.
1. The fight or flight response - Alarm
This response, initiated by nerve impulses from the Hypothalamus to the ANS & the Adrenal medulla,
consists of at least 1400 cascading chemical reactions that we are currently aware of. It quickly mobilises
the body’s resources for immediate physical activity. It brings huge amounts of glucose & oxygen to the
organs that are most active in warding off danger;-
• The brain, which becomes highly alert
• The skeletal muscles - to flee danger
• The heart - to supply blood to the brain & muscles.
Non essential functions are shut down, such as digestion, urinary & reproductive.
Blood supply to the skin is reduced along with other non essential organs. Reduction of blood to the kidneys
sets up the renin-angiotensin-aldosterone pathway to retain sodium & water & raise blood pressure – the
body’s way of preparing for severe bleeding following attack.
2. Resistance Reaction
Unlike the short lived fight/flight response, the resistance reaction is in the large part by hypothalamic
releasing hormones & is a longer lasting response. The hormones involved (CRH, GHRH & TRH) stimulate
the Adrenal Cortex to increase release of Cortisol. The Cortisol then stimulates gluconeogenesis by liver
cells, Lypolysis & catabolism of proteins into amino acids so that the body can use the resulting glucose,
fatty acids & amino acids into ATP( energy) or to repair damaged cells. Cortisol also reduces inflammation.
Thyroid hormones are also secreted that stimulate the increased use of glucose for ATP production.
The resistance stage helps the body continue fighting a stressor long after the fight/flight response dissipates
& it is usually successful at seeing through a stressful episode & the body returns to normal once the event
is over via the negative feedback loop.
However if the stressor is chronic then this stage can remain constant over a long period of time –
sometimes for many years, altering the body’s normal homeostatic response & making the stressed state
become the norm. One major acute incident can also have the same long term effect. However in both cases
the body will reach the 3rd & final stage.
3. Adrenal Exhaustion
This is the stage at which Western medicine would normally recognise as being problematic. Prolonged
exposure to high levels of cortisol & other hormones involved in the resistance reaction are now causing a
plethora of problems.
The adrenal glands cannot continue working at this rate & are now unable to function normally. The
production of cortisol plummets & many other hormones/chemical reactions become disregulated as it is
reduced to a dangerously low level.
Typically a blood serum test can show adrenal distress.
Prolonged high levels of Cortisol affect the body in many ways.
Low levels of cortisol can have an equally as devastating an effect on body.
Low Cortisol and Metabolism
• An insufficient amount of cortisol disrupts thyroid hormone production, which is the main gland in
control of metabolism. A metabolism altered by low cortisol results in low blood sugar levels and reduced
glycogen storage in the liver, which is used to quickly convert into glucose when a quick burst of energy is
required. As such, the initial symptoms of low cortisol are much like those of diabetes, such as fatigue,
lethargy, weakness, brain fog, headaches and gastrointestinal problems. Low cortisol levels lead to not
enough glucose in the blood for the cells to use, even in the presence of adequate insulin.
Levels of Cortisol are directly related to testosterone levels - when one is high the other is low.
Other Effects of Low Cortisol
In addition to early symptoms of fatigue and weakness, low levels of cortisol can also lead to
Most allergies involve the release of histamine and other pro-inflammatory substances (substances that
produce inflammation). Cortisol is a strong anti-inflammatory. In fact, the amount of cortisol circulating in
the blood is a key factor in controlling the level of inflammatory reactions in the body. For this reason,
proper adrenal function plays an important role in mediating the histamine release and inflammatory reactions
that produce the symptoms experienced with allergies. When the adrenals are fatigued they are less likely to
produce enough cortisol to adequately counteract the inflammatory reactions, allowing allergic symptoms to
continue unchecked. People going through times of adrenal fatigue may notice that they seem to have more
allergies or their allergies seem to get worse. Conversely, the more histamine released, the more cortisol it
takes to control the inflammatory response and the harder the adrenals have to work to produce enough
cortisol. The harder the adrenals have to work, the more fatigued they may become and the less cortisol
they produce, allowing histamine to inflame the tissues more.
Testing cortisol levels
Due to the diurnal rhythm of cortisol it is not practical to test in serum & plasma only shows bound cortisol
which is not an accurate assessment of levels, however saliva tests can be undertaken to measure early
morning levels (at peak) and afternoon levels (lowest). In Western medicine synthetic glucocorticoids such
as Prednisolone or Dexamethasone are used to treat low cortisol with some success, however due to the
body’s negative feedback system this can prove detrimental & is only a stop gap to assist the failing adrenals.
When cortisol is low the eyes cannot maintain pupil dilation during bright sunlight, which allows
the opthalmic nerve to be triggered.
Cortisol & Melatonin
Cortisol is released from the adrenal glands in a rhythmic pattern throughout the day. It’s high in the
morning, which energizes the body first thing. It’s at its lowest levels at two a.m. When Melatonin is high.
Melatonin and cortisol are inversely related, so when cortisol is down and Melatonin is up the body is
regenerating. If cortisol levels are high Melatonin levels are reduced, which in turn prevents the body from
its nighttime cellular regeneration cycle.
An increase in supplemental Melatonin will ensure rest & a reduction in elevated cortisol levels, giving the
body a break from the destructive cycle & allowing cellular repair. This may well be the reason that some
headshaking horses are helped by the artificial supplementation of Melatonin due to the reduction of cortisol.
Stress & Aldosterone
Aldosterone is the salt-retaining hormone and is probably the most important mineralocorticoid. It is secreted
by adrenal medulla during alarm reaction of stress along the renin pathway. Alteration of the body’s
secretion of this steroid hormone is affected in the same way as all the other major adrenal components
following chronic or acute stress.
Excesses of aldosterone lead to
• high blood pressure & sodium, and low potassium.
Deficiencies of aldosterone are much less appreciated than deficiencies of cortisol, and lead to
• low blood pressure and high pulse, especially on moving
• the desire to eat salt (salt-craving), due to the excretion of sodium & retention of potassium.
• dizziness or lightheadedness, and palpitations. This may also lead to decreased blood flow to the brain.
• Severe cases may lead to high potassium and low sodium in blood serum tests.
Excesses of cortisol and aldosterone may occur independently, that there may be only excess
aldosterone, only excess cortisol, or excesses of both. Similarly, deficiencies of cortisol and aldosterone
deficiencies may be independent.
During prolonged stress conditions, continued water retention may creates a state of hypertension. Since
while conserving sodium, it stimulate the elimination of potassium and hydrogen ions. This creates a state of
hypokalemia (potassium deficiency in the blood) and alkalosis (excessively high blood pH), resulting in
nervous and muscular system dysfunctions.
Magnesium and Cortisol Lowering
Once the adrenals become overworked and stressed, the body's ability to retain magnesium drops down, as
reflected in a greater loss of magnesium through urinary excretion. For this reason, people with exhausted
adrenals will often require more magnesium to maintain inner balance. Magnesium is also needed by the
adrenals as a basic building block for the manufacturing of hormones. Magnesium, when replenished
properly will lower catecholamines response levels to stress therebye lowering cortisol output. Plus,
magnesium is known as the mineral of insulin sensitivity. Hence, the more insulin resistance one has, the
lower the magnesium levels. Diabetic patients are known to have abysmal magnesium levels. Another
mechanism is that optimal magnesium levels induce more restorative sleep. The more quality sleep, the better
the anabolic cascade, hence, improved body composition.
All headshaking horses have suffered either a single acute stress episode or are in a state of
chronic ‘distress’
Many owners will not recognize or accept this fact particularly if they have homebred or are an experienced/
long term owner, indeed many will not even know what true stress is, believing it to be just an emotional
state. Sometimes owners report that the headshaking has suddenly started without any other symptoms
presenting & often say that it happened following a particularly good day or performance ‘ he put his heart
& soul into it!’ should read ‘he put his entire adrenal system, or what was left of it into it’!
The end result of this distress is Adrenal dysfunction at either stage 2 or stage 3 depending on the strength
of the individual animal. Symptoms differ between horses due to this difference & also due to the fact that
each animal’s physiology will change in a plethora of ways, interacting between the 1400 or so different
hormonal, cellular & chemical changes that will be taking place at any given time. The randomness of these
changes dictates whether or not the horse will show signs of some of the symptoms mentioned, & not
others. This would explain why some horses will become laminitic, some insulin resistant, some
hypothyroid, others hyperthyroid some hypokalemic & some hyperkalemic, and many more metabolic
diseases. Some will suffer nerve dysfunction - headshakers, and many will suffer multiples of these
problems, after being subjected to stress.
Depending at what stage of adrenal dysfunction the horse is will dictate its headshaking behaviour.
At the start of stage 2 the horse may be competing at its optimum, using its adrenal energy & cortisol
reserves. End of stage2/start stage 3, it may be headshaking seasonally, although when warmed up, at an
event or hospitalized for tests it will be producing just enough glucocorticoids to just reach normal levels &
headshaking is reduced. At stage 3 it is no longer able to generate enough cortisol & may be headshaking all
year round.
How are the nerves affected?
As has already been stated, the mineralo/glucocorticoids are responsible for the production of glucose via
gluconeogenesis & also the delicate electrolyte balance within the cell & extracellular fluid.
Nerve cells require nutrients in the form of oxygen & glucose to generate their energy source - adenosine
triphosphate (ATP). ATP moves potassium and sodium at normal physiological concentrations inside and
outside nerve cells (the sodium potassium pump). If oxygen and glucose delivery to nerves is impaired, then
normal levels of ATP will not be generated. This event adversely affects potassium/sodium homeostasis
across the membrane. Additionally if the balance of sodium & potassium is impaired then the repolarization
& resting potential of nerves will be affected, causing irregular neuron activity.
The seasonal effect in some horses is due to the shortening/lengthening of days after the equinox which
signals the pituitary/adrenals to start a coat change. Cortisol levels are affected both diurnally & seasonally,
giving a peak in mid Winter (maximum coat production), dropping at the spring onset (loss of winter coat &
growth of new one) & declining throughout summer. They then rise in Autumn. (Johansson et al 2003)
Nature has compensated for this by a spurt in grass growth at about the same time (February/September)
but this seeks to complicate matters even further as the challenge of producing an entire body of hair &
dealing with an injection of high protein & sugars etc is too challenging to the adrenal reserves. Once the
coat is grown & the days shorten giving an increase in both Melatonin & cortisol, some horses manage to
remain fairly stable. Unfortunately once the horse becomes stable again it is exercised & used as much as
possible to take advantage of this stability instead of being allowed to build up its adrenal reserves & when
Spring arrives for the next coat change the animal is more symptomatic than the previous year until
headshaking becomes a year round problem.
Adrenal Fatigue According to Oriental Medicine
The fundamental principle of health and healing in OM is the concept of balance. The body contains both
Yin and Yang Chi and in health, the relaxed Yin form state balances the Yang functional state. The problem
arises when there is an excess/deficiency of either Yin or Yang influences
In OM the adrenal glands are part of the water element and relate to kidney energy. The kidneys are seen as
the single most important organ affecting the length and quality of life. They control internal Chi, Yin/Yang
balance and house the Jing which is the life force, aliveness, creative power and essence. Abundant kidney
Chi correlates to a strong physical constitution as well as a strong innate sense of purpose and will.
Since the adrenals relate to kidney Chi, Adrenal Fatigue is considered to be a Kidney Yang Deficiency with
Kidney Yin excess (stage2). However, if the condition continues without treatment, it will result in a Kidney
Yin Deficiency (stage 3)
Kidney Yang relates to the reactive, sympathetic nervous system and the secretion of epinephrine and
norepinephrine. In contrast, Kidney Yin is the parasympathetic nervous system relating to the secretion of
cortisol. Just as the body requires some degree of Yang adrenaline hormone to create motivation to react
both to normal as well as life threatening stimulus, it also has a continual need for the Yin hormone, cortisol
to buffer the effects of stress. In the early stages of stress, the body increases its production of cortisol,
while in the later stages its secretion of cortisol is severely diminished. This lack of cortisol is diagnosed as
“Kidney Yin Deficiency.” A deficiency of Yin suggests that the maintaining and repairing function of the
body is depleted or lacking.
Treatment for this disease lies in healing the adrenal system. Once this is done the headshaking & all
other manifestations gradually diminish. It is a process requiring patience & the correct additions to diet &
management, combined with a gradual strengthening exercise regime. OM now has the ability to treat the
adrenal system with the correct diagnosis & combination of herbs & thereby alleviate many of the
symptoms that present themselves with this disease, by strengthening the body & bringing it back to a
natural balance.
References;
Totora J & Derrickson B (2009) Principles of Anatomy & Physiology
Campino et al (2008) Melatonin reduces cortisol response to ACTH
Weinstein R (2011) How stress makes you sick
Tierra M Understanding of the Kidneys
Back to home page
inability to cope with stress in any form)
The following information has been compiled from many years of diagnosing & treating headshaking
horses, together with studies at degree level in Oriental Medicine,Western physiology/bio-chemistry,anatomy
& pathology. Annabelle Knight
The Adrenal glands are 2 small pea shaped endocrine glands located on the
top of each kidney.
Each gland is divided into an outer cortex & an inner medulla.
They each secrete different hormones, the cortex hormones being essential to
life but the medulla hormones not so essential.
The Adrenal Cortex is divided into 3 zones, each of which secretes different
hormones.
• Zona Glomerulosa secretes MINERALCORTICOIDS of which
Aldosterone is the major hormone. It regulates homeostasis of the
2 mineral ions, Sodium (Na+) and Potassium (K+). It also promotes
secretion of H+ in the urine to help prevent acidosis.
The Renin-angiotensin-aldosterone pathway controls secretion of Aldosterone i
n response to blood volume-blood pressure levels.
• Zona Reticularis produces a small amount of weak androgens – steroid hormones that have
masculinizing effects
• Zona Fasciculata secretes mainly GLUCOCORTICOIDS, so named because they affect the glucose
homeostasis as well as regulating metabolism and
resistance to stress. 95% of these hormones are comprised of Cortisol.
Control of cortisol is via a negative feedback system. Low blood levels stimulate cells in the hypothalamus to
secrete CRH (corticotropin-releasing hormone). CRH (together with a low level of cortisol) promotes the
release of ACTH (Adrenocorticotropic hormone) from the anterior pituitary which flows in the blood to the
adrenal cortex where it stimulates glucocorticoid production.
Under normal circumstances, GLUCOCORTICOIDS have the
following functions;
• Protein breakdown.
They increase the rate of protein breakdown, particularly in the
muscle fibers thereby liberating amino acids into the bloodstream for
the synthesis of new proteins or ATP production.
• Glucose formation
They stimulate liver cells to convert certain amino or lactic acids to
glucose for use as ATP production (gluconeogenesis) The body's
most important energy source.
• Lypolysis
They breakdown triglycerides & release of fatty acids from adipose
tissue into the blood.
• Anti-inflammatory effects.
They inhibit white blood cells thereby dampening the inflammatory response. They also retard tissue repair
& as a result slow down wound healing.
• Depression of immune responses.
Interleukin-1 is secreted by the macrophages of the immune system. One action of this is to stimulate
production of ACTH which in turn stimulates production of cortisol to provide resistance to stress and
inflammation. In turn cortisol suppresses further production of Interleukin-1 so switching off this immune
system mediator.
• Resistance to stress
They work in many ways to provide resistance to stress. The additional glucose provided by the liver cells
provides tissues with a ready source of ATP energy to combat a range of stresses including exercise,
fasting, fright, temperature extremes, high altitude, bleeding, surgery, trauma & disease. They also make
blood vessels more sensitive to other hormones that cause vasoconstriction, therefore raising blood
pressure. This would be an advantage in severe blood loss which causes blood pressure to drop.
The Adrenal Medulla is a modified sympathetic ganglion of the ANS & has the ability to quickly release the
hormones epinephrine & norepinephrine (formerly adrenaline & noradrenaline) in response to a stressor.
These greatly augment the flight/flight response by
• Increasing output of the heart.
• Increasing blood flow to the liver, heart, skeletal muscles & adipose tissue.
• Dilate airways to lungs
• Increase blood levels of glucose & fatty acids.
The Stress Response
We live in a world that is constantly bombarding us with every type of stress. Some stress (eustress)
prepares us to meet certain challenges & is therefore helpful. Other stress (distress) is harmful. A stressor
may be almost any disturbance of the body – heat, cold, environmental poisons, heavy bleeding, drugs, or
any strong emotional reaction or event.
The body’s natural homeostatic mechanisms attempt to counteract stress & when they are successful, the
internal environment remains within the physiological parameters.
However if he stress is extreme, unusual or chronic these normal mechanisms may not be enough. This is
when the body starts to undergo changes that compromise health & wellbeing. These changes, called the
stress response, or general adaptation syndrome, are controlled mainly by the hypothalamus & occur in 3
stages as discovered by Hans Selye in 1936.
1. The fight or flight response - Alarm
This response, initiated by nerve impulses from the Hypothalamus to the ANS & the Adrenal medulla,
consists of at least 1400 cascading chemical reactions that we are currently aware of. It quickly mobilises
the body’s resources for immediate physical activity. It brings huge amounts of glucose & oxygen to the
organs that are most active in warding off danger;-
• The brain, which becomes highly alert
• The skeletal muscles - to flee danger
• The heart - to supply blood to the brain & muscles.
Non essential functions are shut down, such as digestion, urinary & reproductive.
Blood supply to the skin is reduced along with other non essential organs. Reduction of blood to the kidneys
sets up the renin-angiotensin-aldosterone pathway to retain sodium & water & raise blood pressure – the
body’s way of preparing for severe bleeding following attack.
2. Resistance Reaction
Unlike the short lived fight/flight response, the resistance reaction is in the large part by hypothalamic
releasing hormones & is a longer lasting response. The hormones involved (CRH, GHRH & TRH) stimulate
the Adrenal Cortex to increase release of Cortisol. The Cortisol then stimulates gluconeogenesis by liver
cells, Lypolysis & catabolism of proteins into amino acids so that the body can use the resulting glucose,
fatty acids & amino acids into ATP( energy) or to repair damaged cells. Cortisol also reduces inflammation.
Thyroid hormones are also secreted that stimulate the increased use of glucose for ATP production.
The resistance stage helps the body continue fighting a stressor long after the fight/flight response dissipates
& it is usually successful at seeing through a stressful episode & the body returns to normal once the event
is over via the negative feedback loop.
However if the stressor is chronic then this stage can remain constant over a long period of time –
sometimes for many years, altering the body’s normal homeostatic response & making the stressed state
become the norm. One major acute incident can also have the same long term effect. However in both cases
the body will reach the 3rd & final stage.
3. Adrenal Exhaustion
This is the stage at which Western medicine would normally recognise as being problematic. Prolonged
exposure to high levels of cortisol & other hormones involved in the resistance reaction are now causing a
plethora of problems.
The adrenal glands cannot continue working at this rate & are now unable to function normally. The
production of cortisol plummets & many other hormones/chemical reactions become disregulated as it is
reduced to a dangerously low level.
Typically a blood serum test can show adrenal distress.
Prolonged high levels of Cortisol affect the body in many ways.
- By suppressing the natural repair functions diseases such as gastritis, colic, arthritis are increased.
- The nerves in the neck & back are affected by increased cortisol activity in preparation for flight, so
there may be pain in these areas. The body’s connective tissue may actually start to disintegrate. - Insulin sensitivity is reduced & blood sugar levels fluctuate leading to intense greed, symptoms of
being ‘a good keeper’ with fat deposits on neck & quarters. Cushings syndrome or laminitis may
occur. - Depressive symptoms & lack of energy, especially between 2pm & 4pm.
- Impatience/irritability/irrational behaviour.
- Overreaction to stressful situations with inability to calm down again
- Noise sensitivity
- Increased gastric secretions – loose droppings particularly when under stress.
- Odour sensitivity
- Migrainous type head pains
- Increased Red blood cell count.
- Reproductive Problems. When the adrenal gland is continually busy producing increased levels of
cortisol, the production of DHEA (dehydroepiandrosterone) is inhibited. DHEA is the precursor for
the reproductive hormones including estrogen, progesterone and testosterone. If there is not enough
DHEA, the balance of reproductive hormone is affected which can cause reproductive problems.
Low levels of cortisol can have an equally as devastating an effect on body.
Low Cortisol and Metabolism
• An insufficient amount of cortisol disrupts thyroid hormone production, which is the main gland in
control of metabolism. A metabolism altered by low cortisol results in low blood sugar levels and reduced
glycogen storage in the liver, which is used to quickly convert into glucose when a quick burst of energy is
required. As such, the initial symptoms of low cortisol are much like those of diabetes, such as fatigue,
lethargy, weakness, brain fog, headaches and gastrointestinal problems. Low cortisol levels lead to not
enough glucose in the blood for the cells to use, even in the presence of adequate insulin.
Levels of Cortisol are directly related to testosterone levels - when one is high the other is low.
Other Effects of Low Cortisol
In addition to early symptoms of fatigue and weakness, low levels of cortisol can also lead to
- Extreme anxiety/fear
- Adrenaline bursts during exercise with the inability to calm down.
- Loss of appetite, sugar craving
- Dry skin/hair
- Skin problems such as sweet itch (frequently treated using cortisones)
- Slow wound healing
- Inflammation/tendon/muscle problems (frequently treated using cortisones)
- Low blood pressure,
- Diarrhea,
- Dehydration/lack of thirst due to low sodium levels
- Inability to tolerate extremes of temperature
- Compromised immunity
- Irritability,
- Depression,
- Colic
- Joint pain
- Aggressive behaviour
- Chronic Anemia
- Lack of normal cortisol will also cause elevated serum potassium levels due to lack of blood sugar
levels, which in turn reduces Insulin production. Insulin has the effect of taking potassium
intracellular thereby lower serum levels. A lack of Cortisol also blocks the release of Potassium
through the kidneys.
Most allergies involve the release of histamine and other pro-inflammatory substances (substances that
produce inflammation). Cortisol is a strong anti-inflammatory. In fact, the amount of cortisol circulating in
the blood is a key factor in controlling the level of inflammatory reactions in the body. For this reason,
proper adrenal function plays an important role in mediating the histamine release and inflammatory reactions
that produce the symptoms experienced with allergies. When the adrenals are fatigued they are less likely to
produce enough cortisol to adequately counteract the inflammatory reactions, allowing allergic symptoms to
continue unchecked. People going through times of adrenal fatigue may notice that they seem to have more
allergies or their allergies seem to get worse. Conversely, the more histamine released, the more cortisol it
takes to control the inflammatory response and the harder the adrenals have to work to produce enough
cortisol. The harder the adrenals have to work, the more fatigued they may become and the less cortisol
they produce, allowing histamine to inflame the tissues more.
Testing cortisol levels
Due to the diurnal rhythm of cortisol it is not practical to test in serum & plasma only shows bound cortisol
which is not an accurate assessment of levels, however saliva tests can be undertaken to measure early
morning levels (at peak) and afternoon levels (lowest). In Western medicine synthetic glucocorticoids such
as Prednisolone or Dexamethasone are used to treat low cortisol with some success, however due to the
body’s negative feedback system this can prove detrimental & is only a stop gap to assist the failing adrenals.
When cortisol is low the eyes cannot maintain pupil dilation during bright sunlight, which allows
the opthalmic nerve to be triggered.
Cortisol & Melatonin
Cortisol is released from the adrenal glands in a rhythmic pattern throughout the day. It’s high in the
morning, which energizes the body first thing. It’s at its lowest levels at two a.m. When Melatonin is high.
Melatonin and cortisol are inversely related, so when cortisol is down and Melatonin is up the body is
regenerating. If cortisol levels are high Melatonin levels are reduced, which in turn prevents the body from
its nighttime cellular regeneration cycle.
An increase in supplemental Melatonin will ensure rest & a reduction in elevated cortisol levels, giving the
body a break from the destructive cycle & allowing cellular repair. This may well be the reason that some
headshaking horses are helped by the artificial supplementation of Melatonin due to the reduction of cortisol.
Stress & Aldosterone
Aldosterone is the salt-retaining hormone and is probably the most important mineralocorticoid. It is secreted
by adrenal medulla during alarm reaction of stress along the renin pathway. Alteration of the body’s
secretion of this steroid hormone is affected in the same way as all the other major adrenal components
following chronic or acute stress.
Excesses of aldosterone lead to
• high blood pressure & sodium, and low potassium.
Deficiencies of aldosterone are much less appreciated than deficiencies of cortisol, and lead to
• low blood pressure and high pulse, especially on moving
• the desire to eat salt (salt-craving), due to the excretion of sodium & retention of potassium.
• dizziness or lightheadedness, and palpitations. This may also lead to decreased blood flow to the brain.
• Severe cases may lead to high potassium and low sodium in blood serum tests.
Excesses of cortisol and aldosterone may occur independently, that there may be only excess
aldosterone, only excess cortisol, or excesses of both. Similarly, deficiencies of cortisol and aldosterone
deficiencies may be independent.
During prolonged stress conditions, continued water retention may creates a state of hypertension. Since
while conserving sodium, it stimulate the elimination of potassium and hydrogen ions. This creates a state of
hypokalemia (potassium deficiency in the blood) and alkalosis (excessively high blood pH), resulting in
nervous and muscular system dysfunctions.
Magnesium and Cortisol Lowering
Once the adrenals become overworked and stressed, the body's ability to retain magnesium drops down, as
reflected in a greater loss of magnesium through urinary excretion. For this reason, people with exhausted
adrenals will often require more magnesium to maintain inner balance. Magnesium is also needed by the
adrenals as a basic building block for the manufacturing of hormones. Magnesium, when replenished
properly will lower catecholamines response levels to stress therebye lowering cortisol output. Plus,
magnesium is known as the mineral of insulin sensitivity. Hence, the more insulin resistance one has, the
lower the magnesium levels. Diabetic patients are known to have abysmal magnesium levels. Another
mechanism is that optimal magnesium levels induce more restorative sleep. The more quality sleep, the better
the anabolic cascade, hence, improved body composition.
All headshaking horses have suffered either a single acute stress episode or are in a state of
chronic ‘distress’
Many owners will not recognize or accept this fact particularly if they have homebred or are an experienced/
long term owner, indeed many will not even know what true stress is, believing it to be just an emotional
state. Sometimes owners report that the headshaking has suddenly started without any other symptoms
presenting & often say that it happened following a particularly good day or performance ‘ he put his heart
& soul into it!’ should read ‘he put his entire adrenal system, or what was left of it into it’!
The end result of this distress is Adrenal dysfunction at either stage 2 or stage 3 depending on the strength
of the individual animal. Symptoms differ between horses due to this difference & also due to the fact that
each animal’s physiology will change in a plethora of ways, interacting between the 1400 or so different
hormonal, cellular & chemical changes that will be taking place at any given time. The randomness of these
changes dictates whether or not the horse will show signs of some of the symptoms mentioned, & not
others. This would explain why some horses will become laminitic, some insulin resistant, some
hypothyroid, others hyperthyroid some hypokalemic & some hyperkalemic, and many more metabolic
diseases. Some will suffer nerve dysfunction - headshakers, and many will suffer multiples of these
problems, after being subjected to stress.
Depending at what stage of adrenal dysfunction the horse is will dictate its headshaking behaviour.
At the start of stage 2 the horse may be competing at its optimum, using its adrenal energy & cortisol
reserves. End of stage2/start stage 3, it may be headshaking seasonally, although when warmed up, at an
event or hospitalized for tests it will be producing just enough glucocorticoids to just reach normal levels &
headshaking is reduced. At stage 3 it is no longer able to generate enough cortisol & may be headshaking all
year round.
How are the nerves affected?
As has already been stated, the mineralo/glucocorticoids are responsible for the production of glucose via
gluconeogenesis & also the delicate electrolyte balance within the cell & extracellular fluid.
Nerve cells require nutrients in the form of oxygen & glucose to generate their energy source - adenosine
triphosphate (ATP). ATP moves potassium and sodium at normal physiological concentrations inside and
outside nerve cells (the sodium potassium pump). If oxygen and glucose delivery to nerves is impaired, then
normal levels of ATP will not be generated. This event adversely affects potassium/sodium homeostasis
across the membrane. Additionally if the balance of sodium & potassium is impaired then the repolarization
& resting potential of nerves will be affected, causing irregular neuron activity.
The seasonal effect in some horses is due to the shortening/lengthening of days after the equinox which
signals the pituitary/adrenals to start a coat change. Cortisol levels are affected both diurnally & seasonally,
giving a peak in mid Winter (maximum coat production), dropping at the spring onset (loss of winter coat &
growth of new one) & declining throughout summer. They then rise in Autumn. (Johansson et al 2003)
Nature has compensated for this by a spurt in grass growth at about the same time (February/September)
but this seeks to complicate matters even further as the challenge of producing an entire body of hair &
dealing with an injection of high protein & sugars etc is too challenging to the adrenal reserves. Once the
coat is grown & the days shorten giving an increase in both Melatonin & cortisol, some horses manage to
remain fairly stable. Unfortunately once the horse becomes stable again it is exercised & used as much as
possible to take advantage of this stability instead of being allowed to build up its adrenal reserves & when
Spring arrives for the next coat change the animal is more symptomatic than the previous year until
headshaking becomes a year round problem.
Adrenal Fatigue According to Oriental Medicine
The fundamental principle of health and healing in OM is the concept of balance. The body contains both
Yin and Yang Chi and in health, the relaxed Yin form state balances the Yang functional state. The problem
arises when there is an excess/deficiency of either Yin or Yang influences
In OM the adrenal glands are part of the water element and relate to kidney energy. The kidneys are seen as
the single most important organ affecting the length and quality of life. They control internal Chi, Yin/Yang
balance and house the Jing which is the life force, aliveness, creative power and essence. Abundant kidney
Chi correlates to a strong physical constitution as well as a strong innate sense of purpose and will.
Since the adrenals relate to kidney Chi, Adrenal Fatigue is considered to be a Kidney Yang Deficiency with
Kidney Yin excess (stage2). However, if the condition continues without treatment, it will result in a Kidney
Yin Deficiency (stage 3)
Kidney Yang relates to the reactive, sympathetic nervous system and the secretion of epinephrine and
norepinephrine. In contrast, Kidney Yin is the parasympathetic nervous system relating to the secretion of
cortisol. Just as the body requires some degree of Yang adrenaline hormone to create motivation to react
both to normal as well as life threatening stimulus, it also has a continual need for the Yin hormone, cortisol
to buffer the effects of stress. In the early stages of stress, the body increases its production of cortisol,
while in the later stages its secretion of cortisol is severely diminished. This lack of cortisol is diagnosed as
“Kidney Yin Deficiency.” A deficiency of Yin suggests that the maintaining and repairing function of the
body is depleted or lacking.
Treatment for this disease lies in healing the adrenal system. Once this is done the headshaking & all
other manifestations gradually diminish. It is a process requiring patience & the correct additions to diet &
management, combined with a gradual strengthening exercise regime. OM now has the ability to treat the
adrenal system with the correct diagnosis & combination of herbs & thereby alleviate many of the
symptoms that present themselves with this disease, by strengthening the body & bringing it back to a
natural balance.
References;
Totora J & Derrickson B (2009) Principles of Anatomy & Physiology
Campino et al (2008) Melatonin reduces cortisol response to ACTH
Weinstein R (2011) How stress makes you sick
Tierra M Understanding of the Kidneys
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