An example of a nose guard to help reduce symptoms of headshaking syndrome.

What is Head-shaking Syndrome?

This condition is characterised by the shaking of the head up and down or side to side acting as though an insect has gone up the nose.

Head-shaking is primarily a disruption or sensitization of the trigeminal nerve.



Causes can be endogenous arising internally (physiologically) or exogenous arising externally (usually environmental triggers).

One of the causative endogenous factors is a disruption to the trigeminal nerve. Of note, post mortems of head shakers have demonstrated that their trigeminal nerves are normal which implies that the physiological state of the nerve can return back to normal.

Endogenous causes may include:

  • Those horses exposed to EHV-1 may be more at risk. The theory behind this is that the herpes virus lies dormant in the trigeminal nerve.  Then with heat, exercise, stress and/or sunlight, becomes active.
  • Lesions, possibly arising from EHV, that exist in the nasal passage can disrupt normal nerve function caused by fluctuations in blood flow particularly during exercise.
  • May be the result of a pathophysiologic mechanism in response to light stimulation. Similar to a light-stimulated sneeze in humans.
  • A weakened physiology either through stress or systemic inflammation may make the horse more prone to headshaking.
  • A reduction in the threshold of perception of the nerve, triggers an excessive response where the horse perceives this as pain and becomes increasingly distressed therefore is difficult to calm down.
  • Most cases have an abrupt onset called ‘acute onset’.  This may be the first time the specific nerve endings have been stimulated or damaged.
  • Sensitivity to light may be due to elevated serotonin levels.
  • Alterations in blood flow in nasal area affect the sensory branches of the trigeminal nerve in the muzzle area which may explain nasal rubbing, snorting.
  • Equine Metabolic Syndrome, insulin resistance, sub-clinical Cushings can trigger non-photic head-shaking.
  • A disruption to gut flora due to the consumption of excess sugars and NSC can lead to a generalized inflammatory response which can trigger headshaking in sensitive horses.
  • Middle ear disorders, ear mites, fungal rhinitis, periodic opthalmia may lead to symptoms of shaking.
  • A disruption to gonadotropin levels ie luteinsing hormone may be higher than should be may sensitize the trigeminal nerve.

Exogenous causes:

These are determined by the horse’s predisposition to environmental factors ie allergies and hypersensitivity to stimuli. 

  • Those horses sensitive to light stimulation will get worse in bright sunlight.
  • Stress, intense exercise, heat and sunlight seem to make head shaking worse in some.
  • Evidence shows that 64% of head shakers are affected seasonally. Normal physiological seasonal processes(ie shedding of coat)  are all determined by day length changes.  Studies on seasonal ACTH and adrenal feedback loops indicate that they vary different times of the year to include changes in reproductive hormone levels.
  • Seasonal head-shaking tends to be  worse on sunny days but improving on overcast, rainy, windy days, at night and indoors.
  • Seasonal head-shaking can be variable ie while most start in the spring and stop in the autumn some start in autumn and stop in spring.
  • 50% of head shakers only show symptoms during exercise indicating blood flow fluctuations as triggers.
  • High potassium levels in the blood can sensitize the nasal region.
  • Low magnesium levels in relation to calcium can trigger head-shaking.

What are the clinical signs and symptoms?  

The signs of headshaking are loosely categorised into reflex responses to include:

  • Up/down involuntary twitching of the head — movement range varies from mild to severe to include twitching, plus ear and eyelid flicks.
  • Pain responses — rubbing, sweating and rearing or striking at the face. Face rubbing is a common sign that corresponds to areas of perceived pain or numbness.
  • High or low head carriage.
  • Snorting or high-blowing, sometimes coupled with nasal discharges and behavioural seeking of muzzle protection (under the tail of another horse, a water bucket, etc).
  • Nostril clamping after exercise may suggest the trigger zone is inside the nasal cavity where normal nostril dilation would lead to pain and discomfort.
  • Distracted behaviour may be seen, such as loss of stride, stopping, rearing and striking at the face during exercise at all paces.
  • True headshaking signs are shown in different circumstances, such as free exercise or lungeing, and with different riders.
  • In some cases the clinical and physiological causes have been resolved but what remains is a behavioural by-product that then presents as an evasion.
  • Ears stuck out at right angles to the head.
  • Horse will actively seek shady areas
  • Symptoms may worsen in summer and improve with nightfall.

Treatment for Head shaking

The Objectives in Treating Head-Shaking Syndrome

  • is to raise the threshold for the firing of the trigeminal nerve (ie damping down the electrochemical processes that activate the nerve) then the problem is reduced to be manageable and /or eliminated.
  • To improve the integrity of mucus membranes and capillaries surrounding the trigeminal nerve. ie treating nasal lesions, addressing any fluctuations in blood flow through the nasal area.
  • To address stress levels and the adrenal response.
  • To modify any environmental, nutritional or physiological triggers.

Veterinary Treatment

As with any condition characterised by pain and suffering we strongly urge that veterinary diagnosis and treatment is investigated and carried out BEFORE attempting to self medicate your horse. Here are some drugs that may be used by your vet.

Have the horse examined by a vet to check for photosensitivity and/or an abnormal build up of seratonin.  Test for any infections. Check teeth and fitting of the bit.

  • Neuropathic drugs are used as an aid to controlling the nerve pain associated with headshaking, while anti-convulsants address involuntary reflex responses movements.
  • Anti-serotonic drugs may be used to calm photic responses
  • Anti-histamines to control allergic reactions.
  • Anti-inflammatory drugs.

  Physical Treatments

These methods may be tried at home and you can use them in combination with any of the other treatments (dietary and drug).

  • If light is a trigger: keep the horse indoors during the day. Consider having the horse wear a UV blocking sun shade fly mask. Try a tinted polo eye guard. This is important if serotonin is the trigger, as sunlight (not direct) on the retina stimulates serotonin production.
  • If exercise is a trigger: Use a nose net or other device which attaches to or dangles over the nostril and muzzle area. Some have found a cut-off piece of panty hose to be effective. Ear covering and forehead ‘dangling’ material may help with allergic responses to midges and pollens.

Alternative Preventative and Herbal Treatment. 


  • Provide environmental protection from sunlight. Plant shade trees.
  • Look at changing the pasture. Contact us directly for the horse pasture blend.
  • Provide additional Magnesium which will raise the threshold for the firing of the trigeminal nerve. (ie damp down the electrochemical processes that activate the nerve)
  • Ashwagandha may be given to help restore healthy nerve cells
  • Reduce inflammation by taking a range of Omega 3 fatty acid  (ALA and GLAs)  . These cold pressed only oils will correct the balance between Prostaglandin E1 and Prostaglandin E2.
  • Omega oils  will help reduce the over-production of noradrenalin which can promote irritability, hostility and excess seratonin.
  • Omega Oil oils may assist in protecting the nerve sheath.
  • Plant material rich in antioxidants and flavonoids will address free radical damage.  Green tea tailings daily, proflavonals from grapeseed, rosehips and Seabuckthorne may help.
  • Restore integrity of blood vessels using some of the following herbs: hawthorn, yarrow, chestnut.
  • To improve blood flow using circulatory herbs like ginkgo and/or white willow bark.
  • Ear mites may be controlled using aromatic oil drops applied to the ears twice daily.
  • The herb valerian will help relax the horse as well as acting as a vasodilator which will prevent fluctuations of  blood flow to muzzle area. Valerian is also used as a diagnostic tool to see what is causing the symptoms ie changes in blood flow within the nasal passages.
  • Camomile flowers may help with symptoms by being slightly sedating, analgesic and anti-inflammatory
  • A blend of anti seratonic herbs, vasodilators, anti-inflammatories like Devil’s Claw may help with symptoms.
  • Some horses have obtained temporary relief after having ointment containing St John’s Wort and Calendula applied up the nostril.( Note St John’s Wort oil acts directly on the nerves. See recipe above.
  • Some people have placed a panty hose leg over the muzzle to prevent pollen entering nasal passages which has in some cases given considerable relief.
  • Ointments containing Melissa Officinalis have been effective in treating humans with a similar condition.

DISCLAIMER: The information in this page must not be used in place of professional veterinary treatment . We recommend that either a qualified herbalist or your animal professional carry out diagnosis and subsequent treatment. Herbal remedies must not be given not be taken in conjunction with other medication with out consulting a medical professional.





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