Horse Shaking Head All Day? Headshaking in Horses Explained

A horse shaking its head at a fly, a raindrop or an itch is doing nothing unusual. Every horse flicks and tosses its head. The behaviour only becomes a problem when it turns frequent, violent, or happens for no reason you can see — and at that point it is very often pain, not temperament. Persistent headshaking is one of the most misunderstood conditions in the horse, and it is routinely mistaken for naughtiness, resistance or a schooling problem for months before anyone calls a vet.

This guide covers why a horse shakes its head, how to tell ordinary head tossing from headshaking syndrome, what triggers episodes, how vets reach a diagnosis, and which treatments actually have evidence behind them. Because this is a clinical subject where a great deal of confidently repeated misinformation circulates, the figures below are quoted from the published papers themselves and each one is named where it appears.

Is It Normal for a Horse to Shake Its Head?

Some head movement is simply part of being a horse. A horse standing out in a summer paddock will flick its head to shift a biting insect, shake water off after rain, or rub an itch on a foreleg. None of that needs investigating. The question is not whether your horse shakes its head, but whether it shakes for a reason you can identify, and whether it stops once that reason is removed.

Headshaking beyond the normal is not rare. In the only published survey of the general UK horse population, Ross, Murray and Roberts (Equine Veterinary Journal, 2018; PMID 28608565) asked 1,014 UK owners about their horses and found an owner-reported prevalence of headshaking in the previous year of 4.6% (95% confidence interval 3.5–6.1), rising to 6.2% of horses that had shown signs at some point since the owner had them. The more severe end of that spectrum — horses affected badly enough to need veterinary attention — is put at around 1% of the equine population in Veronica Roberts’ 2019 review for Veterinary Medicine: Research and Reports (PMID 30666296).

The most striking finding in the Ross paper is not the prevalence figure at all. It is that fewer than one third of headshaking horses (30.2%) had ever been examined by a vet for it, and that where a vet had seen the horse, the cause was still recorded as unknown in 57.9% of cases. Most headshaking in this country is neither investigated nor explained. If your horse is shaking, you are not making a fuss by asking a vet to look.

A rough rule for your own yard: if the shaking has an obvious cause and stops when that cause goes away, it is normal. If your horse shakes hard on a still, fly-free day, or shakes so much that it cannot be ridden or handled safely, that is a clinical problem and it deserves a proper workup.

Head Tossing or Headshaking Syndrome? How to Tell the Difference

This distinction matters more than any other in the article, because the two look superficially alike from the saddle and the management for each is completely different. Behavioural head tossing tends to be tied to a situation: it appears when the horse is asked for something, when the rider takes up a contact, when it is excited, or when it is being asked to do work it finds difficult. It usually eases when the situation changes.

Trigeminal-mediated headshaking looks different. As David Rendle sets out in his Vet Times clinical update on headshaking, the classic sign is sudden, potentially violent flicking or jerking of the head in the absence of any external stimulus — a rapid downward jerk of the nose immediately followed by the head being flung back up. It is bilateral, it is usually worse at exercise, and it comes with signs of nasal irritation rather than signs of resistance.

Three practical questions help separate them:

1. Is there a trigger you can see? Behavioural tossing usually has one. Neuropathic headshaking often has none at all.
2. Does it come with nose signs? Snorting, sneezing, rubbing the muzzle on a foreleg or a fence post, and striking at the face with a front foot point towards nerve pain rather than a training problem.
3. Does it happen without a rider? A horse that shakes in the field, on the lunge and in the stable is not objecting to your hands.

If you are unsure, film it. A short phone video of a genuine episode is worth more to your vet than any description you can give, and episodes are frustratingly good at not happening while the vet is standing there. Our guide to the normal behaviour of horses is a useful baseline for judging what is out of character, and it is worth reading before you conclude a horse is being difficult.

What Causes a Horse Shaking Its Head?

Headshaking is a clinical sign, not a diagnosis. It sits at the end of a long list of possible problems, and the point of an investigation is to work through that list. The good news is that several of the causes are straightforwardly treatable once identified.

Pain and Disease in the Structures of the Head

Almost anything painful between the poll and the nostrils can produce headshaking. The usual suspects are:

• Dental disease — a fractured tooth, a tooth abscess, sharp enamel points, or wolf teeth catching on the bit.
• Sinus pain — equine sinusitis frequently presents with nasal discharge and head discomfort.
• Ear problems — middle and inner ear infection, ticks, and ear mites in horses.
• Eye disease — including equine recurrent uveitis, better known as moon blindness.
• Guttural pouch disease — guttural pouch mycosis is uncommon but serious.
• Upper airway irritation — including equine rhinitis virus infections, which inflame the nasal passages and can produce exactly the snorting and nose-rubbing seen in headshakers.
• Allergic and seasonal airway disease — hay fever in horses and allergies more generally.
• Growths and tumours of the head, and pain further back such as kissing spine or other musculoskeletal soreness that the horse expresses through its head carriage.

The Sussex Equine Hospital headshaking factsheet and the Horse & Hound veterinary library entry on headshaking both set out a similar differential list, and either is worth reading before your vet visit so you know roughly what is being ruled out and why the process takes time.

Tack, Bit and Rider: When a Horse Shakes Its Head Only When Ridden

A horse that shakes only under saddle, and is entirely settled in the field, is telling you something quite specific. Before reaching for a neurological explanation, work through the mechanical ones, because they are common, cheap to check and genuinely fixable.

• Bridle and noseband fit. A drop noseband or a figure-eight noseband sits low across the nasal bones, directly over the branches of the trigeminal nerve that surface there. Fitted too low or too tight, either can cause real discomfort in a horse with a sensitive face. Check the fit of the whole bridle and headpiece, not just the noseband.
• Bit and mouth. Sharp enamel points, retained caps and unerupted teeth all cause trouble under a bit — our guide to horse dentition explains what changes and when.
• Saddle fit and back pain. A horse that is sore behind the saddle very often shows it in front of it.
• Rider contact. A rigid, heavy or unbalanced hand produces head tossing that has nothing to do with disease. Our guide to tacking a horse correctly covers the fitting basics.
• Gastric discomfort. Ulcers in horses are worth considering in any horse whose ridden behaviour has changed, particularly if the change came with a change in workload.

It is worth saying plainly that ruling these out is not a formality you can skip. A horse labelled a headshaker while wearing a badly fitted noseband is a horse being treated for the wrong condition.

Trigeminal-Mediated Headshaking (TMHS)

When the rest of the list has been worked through and nothing turns up, the diagnosis is usually trigeminal-mediated headshaking. It used to be called idiopathic headshaking, which simply meant nobody knew the cause; the name changed once the trigeminal nerve was shown to be involved. You can read our structured summary of the condition in our equine headshaking syndrome entry.

This is a neuropathic pain condition, and that framing matters. The horse is not confused, badly schooled or highly strung. It is experiencing facial pain that arrives without warning and without any external cause.

How the Trigeminal Nerve Causes Headshaking

The trigeminal nerve is the main sensory nerve of the face. It carries touch, temperature and pain signals from the nose, jaw and eyes back to the brain, and it is one of the largest sensory nerves in the head — which is why a fault in it has such a dramatic effect.

The key experimental work is Aleman and colleagues at UC Davis (Journal of Veterinary Internal Medicine, 2013; 27(6):1571–80, PMID 24107198). Working with six affected geldings and six healthy controls, they measured the electrical threshold needed to activate the infraorbital branch of the trigeminal nerve. In affected horses the nerve fired at 5 mA or less; in the controls it took 10 mA or more. In other words the nerve of an affected horse switches on at roughly half the stimulus, or less. Once an impulse had started, every other measurement was normal, and there was no difference between the left and right sides.

Two details from that study are worth holding on to. First, the nerve is structurally normal — it looks healthy under a microscope, and the authors concluded the problem is functional rather than structural. Second, one horse with seasonal headshaking, tested at a time of year when it had no clinical signs, had a threshold like the control horses. The fault comes and goes, which fits what owners of seasonal headshakers describe.

You will see it written in many places that the nerve becomes “around ten times more sensitive than normal”. That figure is widely repeated but it is not what the measurements in the paper show. Rendle, reviewing the same study for Vet Times, describes affected horses as having thresholds “under half those of control horses”, which is what the published numbers support.

The consequence is neuropathic pain. People with trigeminal neuralgia describe burning, tingling, pins and needles, itching and sharp electric-shock sensations across the face, in unpredictable bursts. A horse cannot tell us what it feels, but its behaviour — snorting, rubbing the nose, striking at the face, flicking as though something has flown up a nostril — is exactly what you would expect from that kind of pain.

What Sets Headshaking Off? Common Triggers

Knowing what sets your horse off is genuinely useful, both for managing the condition day to day and for giving your vet a clear history. The best recent data on triggers comes from Bell, Kyriazopoulou, Mowbray and Murphy (Animals, 2024; 14(6):875, PMID 38539973), an owner survey of 216 headshaking horses. It was conducted in Australia, and the authors note its findings agreed with surveys from the Northern Hemisphere.

Bright Light and Sunshine

Light was the single most commonly reported trigger in the Bell survey, named by 61% of owners. Horses whose signs track sunlight are sometimes described as photic headshakers. Rendle notes one plausible mechanism: cross-activation between the optic nerve and the maxillary branch of the trigeminal nerve, or co-activation of adjacent parasympathetic branches.

Exercise

Exercise is the other near-constant. Roberts’ review is explicit that horses are usually more severely affected at exercise, to the point of being unable to do their job or unsafe to ride. Importantly this means any exercise, not just ridden work — a horse that shakes on the lunge or loose in the school is showing the same thing. The likeliest explanation is simply the increased flow of air over the nasal mucosa, and signs often worsen at faster paces or after a step up in workload.

Wind, Rain and Weather: Where the Evidence Disagrees

This is one of the few places where two good surveys point in opposite directions, and it is worth knowing rather than papering over. Mills, Cook, Taylor and Jones (Veterinary Record, 2002; 150(8):236–40, PMID 11916024) analysed 254 headshaking horses and found that seasonal headshaking was significantly worse on sunny days but improved on rainy days, on windy days, at night and indoors. Bell’s 2024 survey, by contrast, put wind as the second most common trigger at 46%.

The practical reading is that wind and rain are not reliable predictors in either direction, and that your own horse’s pattern beats any general rule. Keep a simple diary of conditions alongside the severity of signs; it will tell you more about your horse than the literature can.

Pollen, Dust and Allergy

High pollen was the third most commonly named trigger in the Bell survey, at 40%. That said, World Horse Welfare’s advice, externally reviewed by Dr Veronica Roberts, is clear that the environmental association in trigeminal-mediated headshaking does not appear to be an allergy as such. Genuine allergic airway disease is a separate diagnosis worth chasing in its own right — see our guides to managing hay fever and sweet itch.

Other Reported Triggers

Rendle records a long tail of individual triggers: loud noises, eating, being tacked up, contact with the nose, and stress. Some horses react to fibrous or tough feed that puts pressure on the nasal area. If your horse has an unusual and consistent trigger, it is real information, not a coincidence — write it down.

Symptoms to Watch For

The classic sign is repeated vertical headshaking: a sharp downward flick of the nose followed by the head being thrown up, as though the horse has been stung. Side-to-side and rotary movement occurs, but vertical is the typical pattern, and it is the pattern most associated with the trigeminal form.

Alongside the shaking, look for:

• Snorting, sneezing and repeated nose blowing.
• Rubbing the nose or muzzle on the forelimbs, the ground, fences or trees — sometimes violently enough to cause self-trauma.
• Striking at the face with a front leg.
• An anxious facial expression, often appearing just before an episode starts.
• A low or guarded head carriage, and clamping of the nostrils.
• Nasal or eye discharge.
• Active avoidance of light, wind or warmth on the face.

Signs are typically worse at exercise, but they are not confined to it. In the Ross survey, 19% of headshaking horses were reported to shake at rest. A horse shaking hard while simply standing in its stable is at the more serious end of the spectrum.

Severe cases are genuinely dangerous. A badly affected horse may injure its own face, struggle to eat, and become unsafe to ride or handle. World Horse Welfare’s advice on this is unambiguous, and we would repeat it: if your horse is headshaking badly at rest and appears distressed, contact your vet urgently.

Which Horses Are Most at Risk?

Age. Headshaking is a condition of adult horses in their prime rather than of youngsters or veterans. In the Bell survey, the mean age at onset was 9.6 years (standard deviation 4.7). Rendle puts the median age of onset across published reports consistently at eight to ten years, while noting the range is wide, and Mills’ 2002 analysis found headshaking could develop at any age.

Sex. This is more contested than it is usually presented. Clinic and survey populations are consistently gelding-heavy: Bell found 76% of affected horses were geldings against 24% mares, Mills found twice as many males as females, and Rendle and Roberts both give figures in the 63–72% range. Bell also found onset came later in geldings than mares (10.1 years against 7.9 years). But the one study that sampled the general UK horse population rather than referred cases — Ross and colleagues, 2018 — found no association with sex at all. The honest position is that geldings dominate the caseload and we do not know whether that reflects true risk or which horses get referred.

A theory doing the rounds is that geldings miss the springtime rise in sex hormones that intact horses get. It has been tested. Sheldon and colleagues (Journal of Veterinary Internal Medicine, 2019; 33(2):885–8, PMID 30773684) sampled luteinizing hormone every 15 minutes over eight hours in six affected and six control geldings during the summer and found no significant difference. The theory is not supported by that work.

Breed. All breeds appear susceptible. Rendle notes Thoroughbreds were over-represented in one study and that racehorses are rarely affected, which may reflect their age and type of work rather than any protection. Ross and colleagues found no association with breed. Treat breed as a weak signal at best.

How Vets Diagnose Headshaking in Horses

There is no single test that confirms trigeminal-mediated headshaking. It is a diagnosis of exclusion, reached by ruling out everything else, and that is why the process can feel slow and expensive to an owner who just wants an answer.

A typical pathway looks like this:

1. History and video. Your vet will want to know when the signs started, what makes them better or worse, whether they happen at rest, and what has changed in the horse's work, tack or management. Bring video.
2. Full physical and head examination — teeth, jaws, ears, eyes, sinuses and the upper airway.
3. Tack and ridden assessment, if the signs are confined to ridden work.
4. Further imaging and endoscopy — radiographs, upper airway endoscopy, and where indicated advanced imaging. CT is the single most useful modality for eliminating other causes in the head, and MRI scans have a role in selected cases.
5. Bloods and allergy testing where the history suggests it.
6. Referral to an equine hospital with specialists and a CT scanner, which is the surest way to be confident of the diagnosis.

Set your expectations accordingly. In the Ross survey, of the headshaking horses that had been seen by a vet, the cause remained unknown in 57.9%. A meaningful proportion of horses that look like textbook headshakers turn out at referral to have something else entirely, which is the main argument for going through the full workup rather than assuming.

Headshaking in Horses: Treatment and Management Options

There is no cure for trigeminal-mediated headshaking. Treatment aims to reduce the signs to a level the horse can live with comfortably. If a specific underlying cause is found — a tooth, a sinus, an ear — treating that should resolve the shaking, which is the whole reason the diagnostic workup is worth the money.

Bell’s survey gives a useful picture of what owners actually do: 71% were using two or more treatments at once. Supplements were the most common (68%), then nose nets (63%), light-blocking masks (48%), bodywork (48%) and pharmaceuticals (38%). Sobering context for all of the below: 33% of owners considered their treatments ineffective.

Nose Nets: The First Thing to Try

A nose net is cheap, non-invasive and risk-free, which is why World Horse Welfare recommends it as the first thing to try. It is thought to work by constantly stimulating the nerve, helping to override the pain signals — the same principle as rubbing your elbow after you bang it.

The field study is Mills and Taylor (Veterinary Record, 2003; 152(2):41–4, PMID 12553579), in which 36 owners of seasonally headshaking horses trialled three net designs, each for a week. Their results, in their own numbers:

• Roughly 75% of owners reported some overall improvement with each net.
• Around 60% recorded an improvement of 50% or greater.
• 30% recorded an improvement of 70% or greater.
• The nets significantly reduced up-and-down headshaking, nose flipping, shaking at exercise, shaking when excited, and shaking in bright sunlight or wind.
• They did not significantly affect side-to-side headshaking, shaking at rest, or nose rubbing while stationary.
• The larger-mesh half nets were significantly better than the traditional full net at one thing specifically: the “bee up the nose” behaviour.
• Horses over ten years old were less likely to achieve a 50% or greater improvement in nose flipping and shaking at exercise.

Note the flip side of those numbers, because it is easy to read them too optimistically: a large minority of horses get no useful benefit, some are reported as worse in a net, and a 70% improvement is not enough if the horse is severely affected. Try all three designs before you conclude nets do not work for your horse. If you compete, check the current rules first — nose nets are permitted in most competition at most levels but the detail varies by discipline and level, so read the live British Dressage competition rules or your own governing body’s rulebook rather than relying on what someone told you at a show.

Fly Masks, UV Protection and Light-Blocking

For horses whose signs track sunlight, a UV-blocking fly mask or tinted eye protection is a reasonable, low-cost thing to try alongside a net. Temper your expectations: light-blocking masks were used by 48% of owners in Bell’s survey, and the authors specifically flagged the contrast between bright light being the most-reported trigger and the low perceived efficacy of masks.

Magnesium, Boron and Diet

Magnesium calms nerve firing and is low-risk, which makes it a sensible part of a broader approach rather than a cure in itself. The controlled trial is Sheldon and colleagues at UC Davis (Journal of Veterinary Internal Medicine, 2019; 33(3):1464–72, PMID 30990929), a 42-day randomised dietary trial in twelve geldings, six of them affected. Measured against an unsupplemented hay diet, headshaking behaviour fell by:

• 44% on the pelleted feed alone,
• 52% on pelleted feed plus magnesium,
• 64% on pelleted feed plus magnesium and boron.

Magnesium with boron performed best, and that is the paper’s conclusion. But read the first line again: the pelleted feed on its own produced a 44% reduction, so a good part of the effect was not magnesium-specific, and the trial ran in six affected horses. It is encouraging evidence, not a settled protocol. Talk to your vet before supplementing, and have blood magnesium monitored if you do.

Medication

Where physical aids and diet are not enough, vets may try drugs borrowed from human neuropathic pain management — carbamazepine, alone or combined with cyproheptadine, and others including melatonin. Roberts’ review is candid about them: results are mixed, response is individual and cannot be predicted, a positive response is sometimes only short-term, and some horses become drowsy enough that you need to think about whether they are safe to ride or handle. In the owner survey Roberts cites, no drug stood out as more successful than the others. Medicated horses may also be ineligible to compete, so check before you start.

We are deliberately not quoting doses or course lengths here. These are prescription decisions that depend on the individual horse, and they belong to your vet.

EquiPENS Neuromodulation

EquiPENS is percutaneous electrical nerve stimulation of the trigeminal nerve, adapted from a human neuropathic pain technique. The largest published series is Roberts, Bailey and Patel (Equine Veterinary Journal, 2020; 52(2):238–43, PMID 31461784), covering 168 horses and 530 procedures across multiple centres:

• Horses received an initial course of three procedures, with further procedures if they went into remission and then relapsed.
• Remission after that initial course occurred in 53% (72 of 136 horses).
• The median length of remission was 9.5 weeks, with a range from 2 days to 156 weeks and ongoing.
• Where signs came back, most horses went back into remission after further procedures, usually for longer than the time before.
• The complication rate was 8.8% of procedures, and in all but one case complications were mild and transient with no self-trauma.

That median of just under ten weeks is the number to hold on to, because “a 50% remission rate” on its own sounds far more permanent than the data supports. The authors also note there was no placebo or control group and outcomes were owner-assessed. EquiPENS is low-risk but expensive, and only available at a limited number of equine hospitals.

Surgery: A Last Resort

Surgical options exist and the published results explain why they are reserved for severe cases. Roberts’ review records that bilateral infraorbital neurectomy was effective in only three of nineteen horses, with serious side effects common. Caudal ablation of the infraorbital nerve by coil compression did better — around a 50% success rate in 57 horses — but 26% relapsed at a median of nine months (range two months to five years), most horses developed nose-rubbing side effects, and four of 58 were euthanised because those side effects were severe or would not resolve. Permanent tracheostomy has also been described.

What Else Owners Try

Bodywork was used by 48% of owners in the Bell survey, and approaches such as equine osteopathy are popular. Roberts’ review notes that in a survey of headshaking owners, no treatment — antihistamines, antimicrobials, corticosteroids, NSAIDs, melatonin, chiropractic or acupuncture — stood out as more successful than the rest. That is not an argument against trying them, but it is an argument for judging them honestly against your own diary of signs rather than against hope.

What’s the Outlook for a Headshaking Horse?

The prognosis depends almost entirely on severity. Mildly affected horses generally do well and can be managed successfully for years, often with nothing more than a nose net, a mask and sensible adjustments to when and where they work. Severely affected horses have a considerably poorer outlook, and the reason is welfare rather than performance — this is a pain condition, and a horse in unrelieved facial pain is suffering whether or not it is in work.

On spontaneous recovery, be careful what you promise yourself. Roberts’ review states plainly that there are no longitudinal studies following disease progression, and reports only a suggestion that around 5% of horses may enter long-term spontaneous remission. Remission does happen, and the fact that it can happen at all supports the idea that the nerve fault is functional and reversible. But it is a minority outcome resting on thin evidence, and it is not a management plan.

It has to be said that in the worst cases, where nothing helps and the horse’s welfare is genuinely compromised, euthanasia is considered. Both Roberts and Rendle note that this is an all-too-common outcome in severely affected horses. That is a decision to make with your vet, with the horse’s day-to-day experience as the deciding factor.

Can Headshaking Be Prevented?

There is no known way to prevent trigeminal-mediated headshaking, because we still do not know why the nerve becomes hypersensitive in the first place. What you can do is catch it early and avoid the traps that waste months.

• Do not assume it is behaviour. The single most common mistake is months of schooling, stronger bits and firmer hands applied to a horse in facial pain.
• Get the mechanical causes ruled out early — teeth, tack fit, saddle, bridle and back.
• Keep a diary of dates, weather, light, work and severity. It is the cheapest diagnostic tool you own and your vet will thank you for it.
• Film episodes whenever you can.
• Manage around known triggers — work at dawn or dusk rather than in bright midday sun if light is the trigger, and use a net and mask routinely rather than only on bad days.
• Review before each season. If your horse is seasonal, put management in place before the signs start rather than after.

When to Call Your Vet

Call your vet urgently if your horse is headshaking badly at rest and appears distressed, or if it is injuring its own face, struggling to eat, or has become dangerous to handle. That is World Horse Welfare’s advice and we would not soften it.

Book a routine appointment if the shaking is frequent, violent or unexplained, if it is interfering with ridden work, if it has come on suddenly in a horse that never did it, or if it comes with nasal or eye discharge. Given that fewer than a third of headshaking horses in the Ross survey had ever been examined for it, the most common error by a distance is waiting too long.

Take with you: your diary, your videos, and a list of what you have already changed — tack, feed, work, turnout. It shortens the process considerably.

Frequently Asked Questions