Horse Headshaking Syndrome: Causes and Management Options

Reviewed by Dr. Ali Ehtisham, DVM

Few conditions in equine practice are as frustrating for owners, as distressing to observe, and as difficult to manage as headshaking syndrome. A horse that was once a reliable working partner may suddenly begin making violent, involuntary head movements during ridden work — flicking the head vertically, rubbing its nose on its foreleg, snorting, and appearing intensely distressed. The condition is frequently dismissed as a behavioural problem, a training issue, or the horse "playing up." It is none of these things. Headshaking syndrome is a genuine neurological condition causing real and severe facial pain, and understanding it as such is the starting point for effective management.

What is Headshaking Syndrome?

Equine headshaking syndrome is characterised by involuntary, repetitive, violent vertical movement of the head — typically described as a sharp upward flick rather than a horizontal shake. Affected horses frequently rub their noses on their forelimbs, on the ground, or on any available surface — a response to the abnormal sensations they are experiencing in the nasal and facial region. The behaviour is involuntary; the horse has no more control over it than a human with severe trigeminal neuralgia has over their pain episodes.

Headshaking is typically worse during ridden work than at rest. It is aggravated by bright sunlight, warm temperatures, wind blowing into the face, and exercise-related increases in neural activity. Many horses are significantly worse in spring and summer — the peak season for bright light and warmth — and better or absent in winter, which can lead to the mistaken impression that the horse has "recovered." Horses that are affected year-round typically have more severe underlying trigeminal hypersensitivity.

The Primary Cause: Trigeminal-Mediated Headshaking

Extensive research — including work by Professor Derek Knottenbelt and colleagues at the University of Liverpool and referral institutions across Europe and North America — has established that the majority of genuine equine headshaking syndrome cases are caused by trigeminal neuropathic pain. The trigeminal nerve (cranial nerve V) is the primary sensory nerve of the face, supplying sensation to the muzzle, nasal passages, and sinuses. In affected horses, this nerve is hyperexcitable — it fires abnormally in response to stimuli that would not cause pain in a normal horse, including light touch, airflow, temperature change, and the vasodilation that accompanies exercise.

The experience is frequently compared to severe trigeminal neuralgia in humans — a condition characterised by electric-shock-like facial pain of extreme intensity, triggered by minimal stimuli such as wind on the face or touching the cheek. The comparison is not trivial: if horses are experiencing anything comparable, the welfare implications of the condition and of inadequately managed cases are significant.

Other Causes to Rule Out First

Before diagnosing trigeminal-mediated headshaking, a thorough investigation must exclude other conditions that cause head movement or facial discomfort. These include:

Ear problems — middle and inner ear disease, ear mites, grass seeds, or fly irritation can cause head-shaking behaviour that may be confused with trigeminal headshaking. Otoscopic examination is part of the diagnostic workup.

Eye problems — uveitis, conjunctivitis, and corneal disease can cause photophobia and head-shaking. A full ophthalmological examination is necessary.

Dental pain — sharp enamel points, tooth root disease, or temporomandibular joint problems can cause head-shaking, particularly during ridden work with bit contact. A thorough dental examination under sedation is essential.

Sinusitis and guttural pouch disease can cause facial pain and abnormal head movement. Endoscopic and radiographic assessment may be needed in equivocal cases.

Poorly fitting tack — an ill-fitting bridle, a bit causing pain, a browband that is too tight pressing on the ears — can all cause head movement that is not neurological in origin. Tack assessment by an experienced saddle fitter or equine physiotherapist is part of a thorough workup.

Cervical pain — neck pain from arthritic changes or muscle tension can manifest as head-shaking. Veterinary and physiotherapy assessment of the cervical spine is appropriate.

Diagnosis

There is no single diagnostic test that confirms trigeminal-mediated headshaking. Diagnosis is primarily a diagnosis of exclusion — confirming the condition after other causes have been systematically ruled out. The pattern of clinical presentation — seasonal or worsened by light and exercise, characteristic nose-rubbing behaviour, absence of other identifiable cause — is highly suggestive.

Diagnostic nerve blocks of the infraorbital nerve — which supplies sensation to the nose and muzzle — can help confirm the trigeminal origin. In a horse with trigeminal-mediated headshaking, blocking this nerve typically produces a rapid and marked reduction in the headshaking behaviour during ridden exercise, which supports the diagnosis. Magnetic resonance imaging of the head is available at specialist referral centres and can identify structural abnormalities of the trigeminal nerve pathway.

Management Options

Management of equine headshaking is typically multimodal — combining several approaches to achieve the best possible reduction in severity. No single treatment works reliably for all horses, and owners should expect a period of trialling different interventions.

Nose Net

A mesh nose net worn over the muzzle during ridden work reduces airflow turbulence over the sensitive nasal skin and muzzle, which in some horses is a significant trigger for abnormal nerve firing. Clinical studies report meaningful improvement in approximately a quarter to a third of horses with nose nets alone. They are inexpensive, non-invasive, and carry no side effects, making them a logical first-line intervention.

UV-Blocking Fly Mask

For horses with a significant photic (light-sensitive) component, a UV-blocking fly mask that reduces the amount of bright light reaching the eyes can reduce the frequency and severity of episodes. Tinted or UV-filtering lenses are available in equine fly masks specifically designed for photosensitive horses. Avoiding work in very bright conditions or at midday in summer may also reduce the severity of photic headshaking.

Magnesium Supplementation

Magnesium plays a role in neural membrane stability and nerve excitability. Some clinical evidence and widespread practitioner experience support the use of magnesium supplementation — typically magnesium oxide or magnesium chloride — as part of a management programme for headshaking horses. It is not effective for all horses, but it is safe, inexpensive, and worth trialling for a minimum of four to six weeks before drawing conclusions. Dose and form should be discussed with a veterinarian.

Cyproheptadine

Cyproheptadine is an antihistamine with serotonin-antagonist properties. Its use in equine headshaking is off-label, but it has been used in the field for many years and some horses show positive responses. Its mechanism of action in this context is not fully understood — it may reduce photic sensitisation or modulate serotonin pathways involved in trigeminal sensitisation. It is typically administered daily and requires veterinary prescription.

Carbamazepine

Carbamazepine is an anticonvulsant and nerve pain medication used in human trigeminal neuralgia. Its use in horses is off-label and requires veterinary prescription. Some horses show significant responses to carbamazepine, though it has a relatively short half-life in horses and may require multiple daily dosing to maintain effective levels. Side effects including sedation must be monitored.

PENS — Percutaneous Electrical Nerve Stimulation

The most promising recent development in trigeminal headshaking management is percutaneous electrical nerve stimulation (PENS) using surgically implanted electrodes around the infraorbital nerve — the main branch of the trigeminal nerve supplying the muzzle and nasal region. The implanted device delivers controlled, regular electrical stimulation that modulates abnormal trigeminal nerve firing, reducing or eliminating the neuropathic pain triggers. Studies from specialist equine centres report significant improvement in a high proportion of horses — in some case series, the majority of implanted horses showed meaningful reduction in headshaking severity. Specialist surgical referral is required and the procedure is not inexpensive, but for genuinely refractory cases it represents the most effective intervention currently available.

Prognosis

Prognosis varies considerably. Horses with mild, seasonal headshaking that is well managed with nose nets and trigger avoidance may continue in regular ridden work indefinitely with good quality of life. Horses with moderate cases that respond to medication and physical management can often remain in work with appropriate adjustments. Horses with severe, year-round, medication-resistant headshaking are sometimes retired from ridden work — a difficult but sometimes necessary welfare decision. Quality of life for horses at rest is typically good, as the condition is significantly worse during work than in the stable or field.

Frequently Asked Questions

What causes headshaking in horses?

The most common identified cause is trigeminal-mediated neuropathic pain — hypersensitivity of the trigeminal nerve causing abnormal pain signals in the face triggered by light, temperature, wind, and exercise. Other causes including ear problems, dental pain, sinusitis, and ill-fitting tack must be excluded before this diagnosis is confirmed.

Is headshaking in horses curable?

There is no guaranteed cure for trigeminal-mediated headshaking. Management aims to reduce severity sufficiently to allow comfortable work and good welfare. The PENS implant procedure has produced significant improvement in a meaningful proportion of horses at specialist referral centres. Some horses improve dramatically; others remain difficult to manage and may need retirement from ridden work.

What is a nose net for headshaking?

A mesh net worn over the horse's muzzle during ridden work to reduce airflow stimulation of the sensitive nasal skin, which can trigger abnormal trigeminal nerve firing. Approximately a quarter to a third of horses show meaningful improvement with nose nets. They are inexpensive, non-invasive, and a sensible first-line trial.

Is headshaking dangerous for the rider?

Mild headshaking is manageable, but severe, violent, continuous head movement during ridden work is a genuine safety risk. A horse in severe distress that makes unpredictable large head movements should not be ridden until effective management reduces severity. Welfare must be considered alongside rider safety.

What treatment works best for equine headshaking syndrome?

No single treatment works for all horses. PENS infraorbital nerve implants at specialist referral centres have shown the strongest evidence of benefit for refractory cases. A combination of nose net, UV eye protection, magnesium supplementation, and veterinary-prescribed medication (cyproheptadine or carbamazepine) manages many moderate cases effectively.

---

Disclaimer: This article is for educational purposes only and does not constitute veterinary advice. Always consult a licensed equine veterinarian for diagnosis and treatment.