Head Shaking Syndrome 101: Causes, Symptoms, and Recovery

Headshaking in horses is a stressful condition for both the animal and the rider. Even though increasingly studied, little is known about the triggers of abnormal headshaking in mounts. Subsequently, owners are becoming more desperate for information as that which is available is often not clear or is specific to a particular researcher’s area of expertise. This article is a detailed guide to head shaking syndrome in horses.

What Is the Head Shaking Syndrome?

This syndrome, also known as idiopathic headshaking, is defined as the sudden, erratic, and often involuntary tossing of the head. It may occur to such a degree that either the rider and horse are thrown off-balance or, in unfortunate occasions, the rider is hit in the face. The more common triggers are when the horse shakes its head when bothered by flies or when it is feeling anxious like at the beginning of a race. However, abnormal headshaking is when this quivering occurs for no apparent reason. The severity of the shaking varies widely between individuals, as such, the distinction becomes vague between those suffering from headshaking syndrome, and those that are ‘head bobbers’ or ‘nodders’ (mounts that bob their heads out of boredom than for the symptoms of head shaking syndrome).

Symptoms of the Head Shaking Syndrome

Headshaking is a regular and routine reaction from the horse when it is bitten or annoyed by insects. However, violent, uncontrolled, and persistent vertical headshaking in the absence of troublesome insects is considered abnormal. Other symptoms that may appear

  • Head twisting or slinging
  • Rubbing its muzzle and nose frantically on objects
  • Inflamed nostril
  • Sores on face
  • Banging of head against the stall
  • Loss of hair on the face
  • Snorting
  • Sneezing
  • Coughing
  • Severe headshaking in sunlight, heat, wind, or exercise
  • Eye swelling or tearing
  • Anxiety
  • Depression


Scientists hypothesize that this syndrome might be triggered by strong light which is known as photic headshaking. Intense light stimulates the 5th Cranial Nerve in the mount’s face which results in uncontrollable itching, pain, and sneezing.

This phenomenon is found to occur in 25% of humans as well and is known as the ‘ACHOU syndrome’ or the photic sneeze. In humans, the photic sneeze is hereditary and could be as well in horses.

The other hypothesis is trigeminal headshaking. Here, the horse’s trigeminal nerve (the nerve which supplies sensations to the face), may be too reactive thus causing normal sensations such as wind, cold, or touch to be severely painful. Some people ail from a condition stemming from the irritation of the trigeminal nerve known as trigeminal neuralgia (TgN), which causes facial pain and muscle paralysis. The origin of TgN, which appears primarily in women over 50, is still under study by neurologists. TgN research might indirectly help us comprehend the head shaking syndrome in horses.

Other studies allege that headshaking could be elicited by vaccinations for rhinopneumonitis which may trigger the herpes virus that lies dormant in the trigeminal nerve of horses.

Head shaking syndrome in horses is not well understood. Research on the condition is just beginning to get systematic, and it appears that it emanates from multiple causes. What’s known, however, is that mounts begin to portray this behavior at maturity.

Determining Your Horse’s Cause for Headshaking

1. Check whether it is behavioral

Sometimes, your mount’s head shaking is behavioral. This is expressed by a neurotic and stereotypic response when resisting training. Stereotypic actions, such as weaving and cribbing, are typical horse reactions to stress. Consult a trainer to help you rule out stereotypical horse behavior as a cause for this condition.

2. Physically induced

.At times, the shaking could be a response to physical discomfort or pain.
So while trying to diagnose your horse’s headshaking syndrome, keep a diary where you jot down the symptoms and other observations you make and share these with the vet.

Treatment & Recovery

At the moment, there is no cure for the head shaking syndrome. The available treatment aims to minimize triggers and to reduce the horse’s response to pain. If you determine that your mount is a photic head shaker, management options include stabling the horse at daytime and turning him out at night or riding them in an indoor arena. Also, a UV light filter face mask could be of assistance.

For trigeminal headshaking, using a nose net such as a pantyhose covering the nose, or a fly mask with a nose extension may help alleviate these symptoms.

For horses that headshake seasonally, a melatonin supplement could be used to trick the body that it is winter and this could reduce the shaking. For more significant success, give the melatonin supplement at 5 pm daily. Magnesium (Mg), has also been found to be useful in alleviating headshaking. To be effective, you may need to administer the supplement at higher doses than those recommended. However, overdosage might cause death, and thus you need to seek guidance from your vet.

If the above treatments don’t help, medication can be considered. Medication currently being used for headshaking includes carbamazepine and cyproheptadine. Both of these medicines act on the brain, and therefore lethargy could be a side effect. Carbamazepine and cyproheptadine can be used together or individually with varying success. Some horses are responsive to these drugs initially, but after a while become indifferent to treatment. Also, these two drugs cannot be used during competitions, and as such, the clinical symptoms of head shaking might manifest during the event. Unfortunately, neither drug has a lasting effect.

There are some surgeries developed to treat the head shaking syndrome. However, these should be a last resort because they are a double-edged sword that could leave the horse in a worse state to the point of necessitating euthanasia.


The head shaking syndrome is a cause for frustration in the horse, owner, and even the veterinarian. You need to work with your vet to rule out other common causes for headshaking before labeling your mount an idiopathic head shaker. Start managing the recovery with one treatment at a time to notice what works for your horse.

Image source: Pixabay

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