Stringhalt in Horses: Signs, Causes and Treatment

By Dr Duncan Houston

Stringhalt is one of those movement problems that can look alarming the first time you see it.

A horse suddenly snatches one hind leg upward, jerks it toward the belly, then slaps it back down. Sometimes it happens every few steps at the walk. Sometimes it only appears when the horse backs up, turns sharply, or takes the first few steps after standing. In mild cases, it can come and go. In severe cases, the movement is dramatic enough to make the horse unsafe or unsuitable for certain work.

The important part is this: stringhalt is not simply a horse being naughty, stiff, cold, or awkward. It is a neuromuscular movement disorder.

But it also should not be diagnosed too casually. Shivers, hindlimb pain, foot pain, upward fixation of the patella, HYPP, EPM, trauma, and other neurological or orthopaedic problems can mimic parts of the picture. The goal is to recognise the pattern, check the pasture, rule out dangerous lookalikes, and manage the horse based on the type and severity.

Quick Answer

Stringhalt, also called equine reflex hypertonia, is a neuromuscular gait abnormality where one or both hind limbs are involuntarily lifted too high, often with a sudden jerking or snapping motion. It is usually most obvious at the walk, when backing, turning sharply, starting after rest, or moving downhill, and it may reduce at trot or disappear at canter. There are two main forms: acquired or pasture-associated stringhalt, often linked with plants such as false dandelion, and idiopathic stringhalt, where no clear cause is found. Mild cases may not prevent light work, but sudden severe signs, weakness, collapse, pain, wounds, or neurological changes need veterinary assessment. Merck Veterinary Manual notes that diagnosis is usually based on clinical signs, and that intoxication-associated cases may improve after removal from the suspect pasture. (Merck Veterinary Manual)

What Is Stringhalt?

Stringhalt is a movement disorder of the hind limbs.

The classic sign is exaggerated, involuntary upward movement of one or both hind legs. The limb may snap up toward the belly, pause, and then strike the ground forcefully. In severe cases, the movement can be so dramatic that the horse appears to hop or stomp. UC Davis describes stringhalt as a neuromuscular condition causing involuntary exaggerated upward movement of one or both hind limbs, usually seen with each stride at the walk, often less obvious at trot and usually absent at canter. (Center for Equine Health)

Stringhalt is also known as:

• Equine reflex hypertonia

• Classic stringhalt

• Idiopathic stringhalt

• Australian stringhalt

• Pasture-associated stringhalt

• Acquired stringhalt

Those names matter because the cause and prognosis can differ.

A horse with pasture-associated stringhalt may improve after being removed from the toxic pasture. A horse with chronic idiopathic stringhalt may not resolve without surgical or long-term management.

What Does Stringhalt Look Like?

Stringhalt can range from subtle to dramatic.

Common signs include:

• Sudden exaggerated lifting of one hind limb

• Jerky, snatching movement of the hind leg

• Hind foot pulled sharply upward toward the belly

• Foot placed down forcefully or awkwardly

• Signs most obvious at walk

• Signs worse when backing

• Signs worse when turning sharply

• Signs worse in the first few steps after standing

• Signs worse going downhill in some horses

• Signs that reduce at trot or canter

• One or both hind limbs affected

• Signs that may be intermittent in mild cases

• Lateral thigh muscle atrophy in severe or chronic cases

Merck describes stringhalt as ranging from mild spasmodic lifting and grounding of the foot to extreme cases where the foot is drawn sharply upward toward the belly and then struck violently back onto the ground. It also notes that signs are often most obvious when the horse is sharply turned or backed, and may be less intense or absent in warmer weather. (Merck Veterinary Manual)

That temperature clue is useful, but not absolute. Do not rule stringhalt in or out based only on weather.

Is Stringhalt Painful?

Stringhalt itself is generally considered a movement abnormality rather than a pain reaction. UC Davis specifically notes that stringhalt is not a reaction to pain, so affected horses are not necessarily uncomfortable. (Center for Equine Health)

That said, pain still matters for three reasons.

First, painful conditions can mimic stringhalt. Merck notes that “false stringhalt” can occur from irritation around the lower pastern or a painful lesion in the foot. (Merck Veterinary Manual)

Second, severe stringhalt can cause secondary soreness or injury because the foot strikes the ground abnormally.

Third, a horse can have stringhalt and another painful condition at the same time.

So the correct question is not just “is stringhalt painful?” It is:

Is this truly stringhalt, or is pain creating a stringhalt-like movement?

Types of Stringhalt

There are two broad categories.

Acquired or Pasture-Associated Stringhalt

This form is often linked with grazing certain pastures, particularly during late summer or autumn when forage is sparse and weeds are prominent.

It is also called:

• Australian stringhalt

• Pasture stringhalt

• Plant-associated stringhalt

• Acquired stringhalt

False dandelion, also called flatweed or catsear, with the scientific name Hypochaeris radicata, is the best-known plant associated with acquired stringhalt. UC Davis notes that the acquired form is often linked with plant toxicity, especially Hypochaeris radicata, and can occur worldwide despite the name “Australian stringhalt.” (Center for Equine Health)

Oregon State University Extension describes pasture stringhalt as being associated with late summer or autumn, hot and dry conditions, limited forage, overgrazed pasture or weedy dry lots, and high populations of Hypochaeris radicata. It also notes that affected horses often recover after removal from the weed-infested area, although recovery may take months or longer. (OSU Extension Service)

A Brazilian outbreak study also reproduced Australian stringhalt experimentally in one colt fed Hypochaeris radicata from suspect paddocks, supporting the link between this plant and some outbreaks. (PubMed)

Idiopathic or Classic Stringhalt

Idiopathic stringhalt means no clear pasture toxin or trigger is found.

It may be:

• Unilateral or bilateral

• Chronic

• Persistent

• Sometimes progressive

• Not linked to a specific pasture outbreak

• Less likely to resolve spontaneously

UC Davis notes that idiopathic cases typically do not resolve on their own, while acquired cases are often temporary. (Center for Equine Health)

Idiopathic stringhalt may sometimes follow injury or trauma involving the back, neck, or limb, but in many horses the cause remains unknown.

Is Australian Stringhalt Only in Australia?

No.

The name is historical, not geographic.

Australian stringhalt was recognised prominently in Australia, but pasture-associated cases have been reported elsewhere, including the United States, Europe, Brazil, and other regions where suspect plants are present. UC Davis notes that acquired stringhalt can occur worldwide and that cases have been reported in California. (Center for Equine Health)

Oregon State University specifically discusses Hypochaeris radicata as an invasive species common in Oregon pastures and associated with stringhalt risk. (OSU Extension Service)

So if your horse is in the United States, do not dismiss pasture-associated stringhalt purely because it is called Australian stringhalt.

How Worried Should You Be?

Low Concern

This is more likely when:

• The movement is mild.

• The horse is otherwise bright and comfortable.

• There is no lameness, weakness, collapse, or pain.

• The horse can walk, trot, and canter safely.

• Signs are intermittent and not worsening.

• There are no other horses affected.

• Pasture-associated weeds have been identified and access has been removed.

Action: book a veterinary assessment, check pasture plants, record videos, and monitor progression. Mild stringhalt is not always career-ending, but it should still be documented and investigated.

Moderate Concern

This is more likely when:

• The hindlimb jerk is obvious at walk.

• The signs appear when backing, turning, or starting after rest.

• One hind limb is more affected than the other.

• The horse struggles with certain movements under saddle.

• False dandelion or other suspect weeds are present.

• More than one horse on the property is showing signs.

• The condition has developed suddenly.

Action: remove the horse from the suspect pasture, provide safe forage, call your vet, and inspect the pasture. Multiple horses affected on the same pasture strongly raises suspicion for a plant-associated problem.

High Concern

This is more likely when:

• The horse has severe hyperflexion.

• The foot strikes the ground forcefully.

• The horse is unsafe to ride or handle.

• Signs are worsening quickly.

• The horse shows muscle wasting or weakness.

• The movement is interfering with farrier work.

• The horse has signs of pain, lameness, or neurological abnormality.

• The diagnosis is uncertain.

Action: stop ridden work and arrange a full veterinary lameness and neurological assessment. Do not assume it is harmless stringhalt if there are pain or neurological red flags.

Critical

Treat this as urgent if:

• The horse is collapsing.

• The horse is weak, ataxic, or uncoordinated.

• The horse is unable to rise.

• The horse is severely lame.

• There is a wound, fracture concern, or acute trauma.

• The horse has muscle trembling, sweating, or dark urine.

• HYPP, tying up, EPM, botulism, or other neurological disease is possible.

• Several horses suddenly develop severe signs.

Action: call your vet immediately. This is no longer a routine stringhalt assessment.

When Is Stringhalt an Emergency?

Stringhalt itself is usually not a same-hour emergency, but stringhalt-like movement can overlap with urgent problems.

Call your vet urgently if your horse has:

• Sudden severe lameness

• Collapse

• Weakness

• Ataxia or wobbliness

• Repeated falling or stumbling

• Inability to rise

• Severe muscle trembling

• Sweating and distress

• Dark urine

• Fever or depression

• A wound or suspected fracture

• Acute neurological signs

• Rapid worsening over hours or days

• Multiple horses affected on the same pasture

The reason to be cautious is simple: stringhalt is a gait pattern, but other diseases can create abnormal hindlimb movement too. A horse with collapse, weakness, dark urine, fever, or severe lameness needs a vet, not a pasture diagnosis from across the fence.

What Else Can Look Like Stringhalt?

This is the most important clinical section.

A hind limb that jerks upward does not automatically equal stringhalt.

Shivers

Shivers is a progressive neurological movement disorder that most often appears when a horse backs up or has a hind foot lifted. It can cause hyperflexion, hyperextension, trembling, and farrier difficulty. UC Davis notes that shivers requires clinical signs while backing up and that horses that only hyperflex when the hind foot is lifted but back normally likely have an orthopaedic issue rather than shivers. (Center for Equine Health)

Stringhalt is usually more obvious during forward walking, especially the first steps, turning, or backing. Shivers is classically obvious when backing and handling the hind feet.

Upward Fixation of the Patella

This can cause a hind limb to lock or release abnormally. Owners may describe a jerky hind leg movement, but the mechanics are different from stringhalt.

Hind Foot or Pastern Pain

Merck notes that false stringhalt can occur from irritation around the lower pastern or painful foot lesions. (Merck Veterinary Manual)

That means hoof abscesses, bruising, pastern pain, wounds, or lower limb irritation can create a stringhalt-like gait.

HYPP

Hyperkalemic periodic paralysis can cause muscle twitching, trembling, weakness, collapse, and abnormal movement in Quarter Horse-related breeds. It is not stringhalt and can be life-threatening in severe episodes.

Tying Up

Exertional rhabdomyolysis can cause stiffness, painful muscles, sweating, reluctance to move, and dark urine. It may be confused with other movement disorders if the horse is stiff or abnormal behind.

EPM and Other Neurological Disease

EPM, cervical spinal cord disease, trauma, and other neurological conditions can cause abnormal limb placement, weakness, ataxia, asymmetry, or gait changes.

Hock, Stifle or Suspensory Pain

Pain higher in the hind limb can alter the way a horse picks up or places the limb.

Trauma

A kick, fall, pelvic injury, fracture, or soft tissue tear can create sudden abnormal hindlimb movement.

The safest rule is:

If the horse is painful, weak, lame, ataxic, or systemically unwell, do not call it simple stringhalt until a vet has ruled out more serious problems.

How Vets Diagnose Stringhalt

Diagnosis is usually based on clinical signs.

Your vet may assess:

• Walk in hand

• Backing

• Tight turns

• First steps after standing

• Movement downhill

• Trot and canter

• Hindlimb flexion and foot handling

• Neurological exam

• Lameness exam

• Hoof and pastern examination

• Video history

• Pasture history

• Whether other horses are affected

• Weed identification

Merck notes that diagnosis is based on clinical signs and can be confirmed by electromyography. It also suggests observing the horse as it is backed out of a stall after hard work for one to two days if the diagnosis is uncertain. (Merck Veterinary Manual)

Electromyography is not required for every case, but it may help in difficult or referral-level cases.

In practice, videos are extremely useful. Record the horse:

• Walking away

• Walking toward the camera

• Turning both directions

• Backing up

• Starting after standing

• Moving downhill if safe

• Trotting and cantering if safe

• Lifting each hind foot if safe

Do not force a horse into unsafe movements just to capture footage.

How Vets Investigate Pasture-Associated Stringhalt

If pasture-associated stringhalt is suspected, your vet may ask:

• When did signs start?

• Did signs appear in late summer or autumn?

• Has the weather been dry?

• Is the pasture overgrazed?

• Is hay being provided?

• Are there weeds or dry lots with limited forage?

• Are multiple horses affected?

• Is Hypochaeris radicata present?

• Did signs improve after removal from pasture?

Oregon State University describes common pasture-associated patterns: late summer or autumn diagnosis, hot and dry conditions, limited forage, overgrazed pasture or weedy dry lots, and high populations of Hypochaeris radicata. (OSU Extension Service)

The pasture history can be just as important as the gait video.

Treatment for Pasture-Associated Stringhalt

The first step is removal from the suspect pasture.

Do this immediately if acquired stringhalt is suspected.

Treatment may include:

• Moving the horse to a clean paddock or stable

• Providing safe hay or forage

• Removing access to suspect weeds

• Pasture renovation or weed control

• Veterinary assessment

• Time and monitoring

• Supportive care

• Physical rehabilitation in selected cases

Merck states that when intoxication is suspected, moving the horse to another paddock may be all that is required, and many intoxication-induced cases appear to recover spontaneously. (Merck Veterinary Manual)

Oregon State University also notes that horses typically recover once removed from weed-infested areas, although recovery can be short in some cases and months or longer in others. (OSU Extension Service)

That is the key owner expectation:

Improvement may not be immediate. Recovery can take weeks, months, or longer.

Treatment for Idiopathic or Chronic Stringhalt

Chronic idiopathic stringhalt is harder.

Options may include:

• Monitoring if signs are mild

• Adjusting workload

• Avoiding triggers such as cold, stress, excitement, or hard exercise

• Farrier and hoof care support

• Physiotherapy or rehab support in selected horses

• Surgery in more severe cases

• Medical therapy in selected cases under veterinary direction

The best documented surgical option is myotenectomy of the lateral digital extensor musculotendinous junction. Merck notes that this has given the best results in chronic cases, although improvement may not be evident for two to three weeks after surgery and not all horses respond. (Merck Veterinary Manual)

This surgery is not for every horse with a mild gait abnormality. It is usually considered when the signs are severe, persistent, function-limiting, or unsafe.

What About Thiamine, Phenytoin and Supplements?

Thiamine and phenytoin are sometimes discussed in stringhalt cases, but they should not be treated as guaranteed cures.

The honest clinical position is:

• Some vets may trial medical therapy in selected cases.

• Evidence is limited and response varies.

• Plant-associated cases may improve mainly because the horse is removed from the pasture.

• Chronic idiopathic cases may not respond well to medication.

• Supplements should not delay proper diagnosis or pasture removal.

If your horse has stringhalt, discuss medication options with your vet. Do not start phenytoin or other neurological drugs without veterinary supervision.

Can a Horse With Stringhalt Still Be Ridden?

Sometimes, yes.

Mild stringhalt may not materially affect a horse’s ability to work. Merck notes that although stringhalt is considered unsoundness, it may not significantly hinder work except in severe cases, but it may make a horse unsuitable for some disciplines such as dressage. (Merck Veterinary Manual)

Riding may be reasonable when:

• Signs are mild and stable.

• The horse is safe.

• There is no pain, weakness, or ataxia.

• The horse can move forward comfortably.

• The discipline does not demand perfect hindlimb expression.

• Your vet has ruled out serious lookalikes.

Avoid riding if:

• Signs are severe.

• The horse is unsafe.

• The foot slams down violently.

• The horse is weak or uncoordinated.

• There is lameness or pain.

• The signs are rapidly worsening.

• The horse is stumbling or falling.

• The diagnosis is uncertain.

A trail horse with mild stable stringhalt may do well. A dressage horse needing precise hindlimb control may be far more limited.

What Should You Do Right Now?

If your horse shows stringhalt-like movement:

1. Stop and Observe Safely

Do not panic, but do not ignore it. Watch the horse walk, turn, and back up if safe.

2. Record Video

Take short videos from the side, behind, and front. Include walking, turning, backing, and the first few steps after standing.

3. Check for Pain and Injury

Look for wounds, swelling, hoof pain, heat, digital pulse changes, or obvious lameness.

4. Call Your Vet

A vet should assess the movement, rule out painful and neurological causes, and help classify the type.

5. Inspect the Pasture

Look for false dandelion, sparse forage, overgrazing, dry lots, and other affected horses.

6. Remove From Suspect Pasture

If plant-associated stringhalt is possible, move the horse to a safer area and provide hay.

7. Do Not Force Work

Avoid hard exercise, tight turns, backing drills, or ridden work until the horse is assessed.

8. Monitor Progress

Track whether signs are improving, stable, or worsening over days to weeks.

Common Mistakes Owners Make

Calling It Behaviour

A horse with stringhalt is not choosing to move that way.

Missing Painful Lookalikes

Foot pain, pastern irritation, hock pain, stifle problems, or trauma can create stringhalt-like signs.

Leaving the Horse on the Same Pasture

If pasture-associated stringhalt is possible, the horse should be removed from the suspect area immediately.

Waiting Because the Horse Is Not “Lame”

Stringhalt is not always classic lameness. Abnormal movement still deserves assessment.

Assuming Every Case Will Recover Quickly

Pasture-associated cases often improve, but recovery may take months or longer.

Starting Supplements Instead of Checking the Pasture

If false dandelion or other weeds are present, changing the environment matters more than buying a tub of mystery powder.

Confusing Stringhalt With Shivers

Shivers and stringhalt can look similar, but they are different movement disorders and have different management implications.

How To Prevent Pasture-Associated Stringhalt

Prevention focuses on pasture management.

Practical steps include:

• Identify false dandelion, also called flatweed or catsear.

• Avoid overgrazing.

• Provide hay when pasture is sparse.

• Rotate pastures to allow grass regrowth.

• Improve pasture density and soil health.

• Control broadleaf weeds where appropriate.

• Move horses off dry, weedy lots with poor forage.

• Inspect pastures in late summer and autumn.

• Watch for multiple horses showing similar signs.

• Work with local extension services for weed identification and control.

Oregon State University notes that false dandelion is difficult to control, mowing is not very effective because it can resprout, and long-term control requires improving pasture conditions, rotating horses, preventing overgrazing, feeding hay when forage is inadequate, and sometimes using selective broadleaf herbicides according to label directions. (OSU Extension Service)

The best prevention is not just removing one weed. It is building pasture that is not so thin and stressed that weeds take over.

Myth vs Reality

Myth	Reality
Stringhalt means the horse is in severe pain.	Stringhalt itself is usually a movement disorder, not a pain reaction, but pain can mimic it.
Australian stringhalt only happens in Australia.	It can occur in other countries where associated plants are present.
If one horse has pasture stringhalt, the others are safe.	Multiple horses on the same pasture may be exposed. Monitor all herd mates.
Normal trotting rules it out.	Stringhalt can be most obvious at walk and may reduce or disappear at trot or canter.
Supplements cure stringhalt.	Some supportive treatments may be tried, but pasture removal, diagnosis, time, and sometimes surgery matter more.
Shivers and stringhalt are the same thing.	They are different movement disorders with overlapping signs.

FAQs About Stringhalt in Horses

Is stringhalt in horses painful?

Stringhalt itself is not usually considered a pain reaction, but painful foot or pastern problems can mimic stringhalt. Severe stringhalt may also cause secondary soreness from abnormal limb movement. (Center for Equine Health)

Can stringhalt go away?

Pasture-associated stringhalt often improves after the horse is removed from the suspect pasture, although recovery can take weeks, months, or longer. Idiopathic stringhalt is less likely to resolve on its own. (Center for Equine Health)

What plants cause stringhalt?

False dandelion, flatweed, or catsear, with the scientific name Hypochaeris radicata, is the best-known plant associated with pasture stringhalt. The exact toxin and why some horses are affected while others are not remain incompletely understood. (Center for Equine Health)

How is stringhalt diagnosed?

Stringhalt is usually diagnosed from clinical signs, especially the characteristic exaggerated hindlimb movement at walk, backing, turning, or starting after rest. Vets may also use lameness and neurological exams, pasture history, video assessment, and electromyography in selected cases. (Merck Veterinary Manual)

Can a horse with stringhalt still work?

Many mildly affected horses can still do light or moderate work if they are safe and comfortable. Severe cases may limit performance, especially in disciplines requiring precise hindlimb control such as dressage. (Merck Veterinary Manual)

The Bottom Line

Stringhalt is a distinctive hindlimb movement disorder where the horse involuntarily lifts one or both hind legs too high, often most obviously at walk, when backing, turning, or starting after rest.

The two major forms are pasture-associated stringhalt and idiopathic stringhalt.

Pasture-associated cases are often linked with dry, sparse, weed-heavy paddocks and plants such as false dandelion. Removing the horse from the suspect pasture and providing safe forage is the first step.

Idiopathic cases are more likely to persist and may require long-term management or, in severe cases, surgery.

The safest approach is:

• Record the movement.

• Check for pain and injury.

• Call your vet.

• Inspect the pasture.

• Remove the horse from suspect grazing.

• Rule out shivers, foot pain, HYPP, tying up, EPM, trauma, and other neurological or orthopaedic problems.

• Monitor improvement over weeks to months.

• Consider surgery only for selected chronic or severe cases.

Stringhalt is not always career-ending, but it is not something to shrug off as “just a funny step.” The pattern deserves a proper diagnosis, especially if it starts suddenly or more than one horse on the property is affected.

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If your horse has a jerky hindlimb gait, sudden hyperflexion, suspected pasture stringhalt, or you are unsure whether it could be shivers, pain, HYPP, or another movement disorder, ASK A VET™ can help you organise videos, pasture photos, timeline, and the right questions to discuss with your treating veterinarian.