Stringhalt

Stringhalt is a neuromuscular condition in horses characterized by involuntary, exaggerated flexion of one or both hindlimbs during movement. This distinctive gait abnormality causes affected horses to snap their hind legs upward toward the abdomen in an uncontrolled, often violent manner before placing the foot back on the ground. The condition can range from barely perceptible hesitation in the hindlimb gait to severe hyperflexion that makes normal locomotion extremely difficult or impossible. Stringhalt represents one of the most recognizable movement disorders in equine medicine, with historical documentation dating back centuries in veterinary literature.

Stringhalt occurs worldwide and affects horses of all breeds, ages, and disciplines, though certain forms demonstrate geographic clustering and seasonal patterns. The condition presents in two primary forms: classic or idiopathic stringhalt, which typically affects a single hindlimb and has no identifiable cause, and Australian or bilateral stringhalt, which affects both hindlimbs and is associated with ingestion of certain toxic plants. Australian stringhalt, despite its name, has been documented in North America, South America, Europe, and New Zealand, typically occurring in late summer and autumn following drought conditions when horses graze on pastures containing specific toxic weeds.

The impact of stringhalt on equine health and performance varies considerably based on severity and the form of the condition. Mild cases may cause only cosmetic concerns with minimal effect on the horse's ability to perform, while severe cases can render horses unable to walk normally, creating significant welfare concerns and making any athletic use impossible. The exaggerated hindlimb movement can cause secondary problems including muscle fatigue, joint stress, and difficulty navigating terrain or obstacles. Horses with severe stringhalt may struggle with basic activities such as backing, turning, and walking on uneven ground, significantly compromising their quality of life.

Treatability of stringhalt depends heavily on its underlying cause and severity. Australian stringhalt cases often improve significantly or resolve completely when horses are removed from contaminated pastures and provided supportive care, though recovery may take months. Idiopathic stringhalt presents greater treatment challenges, with some cases responding to surgical intervention while others remain refractory to all treatments. Early recognition of the condition, identification of potential toxic plant exposure, and prompt intervention offer the best chances for recovery. Working closely with an equine veterinarian to determine the specific form of stringhalt and develop an appropriate treatment plan is essential for achieving optimal outcomes.

The causes of stringhalt vary depending on the form of the condition, with Australian stringhalt having a well-established toxic etiology while idiopathic stringhalt remains poorly understood despite extensive research. Australian stringhalt is caused by ingestion of toxic plants, primarily Hypochaeris radicata (flatweed or catsear), though Taraxacum officinale (dandelion), Malva parviflora (marshmallow weed), and certain other plants have also been implicated. These plants contain neurotoxins that damage the peripheral nerves supplying the hindlimb muscles, particularly affecting the lateral digital extensor and long digital extensor muscles. The toxins appear to cause distal axonopathy, affecting the longest nerve fibers first and resulting in the characteristic hyperflexion gait.

Genetic factors may play a role in susceptibility to stringhalt, as some horses grazing the same toxic pastures remain unaffected while others develop severe signs. Research suggests that individual variations in metabolism, detoxification pathways, or nerve vulnerability may predispose certain horses to developing clinical signs when exposed to plant toxins. For idiopathic stringhalt, a hereditary component has been proposed but not conclusively demonstrated, with occasional reports of multiple related horses being affected. The potential genetic basis for either form of stringhalt remains an area requiring further investigation.

Environmental and management factors significantly influence the development of Australian stringhalt. Drought conditions followed by rain create ideal growing conditions for flatweed and other toxic plants, which flourish in overgrazed or stressed pastures. Horses on poorly maintained pastures with limited forage options are at highest risk, as they may preferentially graze toxic plants that they would normally avoid when better forage is available. The condition typically appears in late summer through autumn, corresponding with the growth cycle of implicated plants and reduced pasture quality. Pasture management practices, stocking density, and supplemental feeding all influence exposure risk.

Risk factors for stringhalt include age, with both very young and older horses potentially showing increased susceptibility. Horses in poor body condition or those experiencing nutritional stress may be more vulnerable to toxic plant effects. The amount and duration of toxin exposure influence disease severity, with horses consuming larger quantities of toxic plants over extended periods typically developing more severe clinical signs. Geographic location matters significantly, as certain regions experience higher rates of Australian stringhalt based on climate conditions and prevalence of toxic plant species. Individual pasture history and previous stringhalt outbreaks on a property indicate ongoing risk.

The pathophysiology of stringhalt involves disruption of normal neuromuscular control of hindlimb movement. In Australian stringhalt, plant toxins cause axonal degeneration in peripheral nerves, particularly affecting the peroneal nerve branches that supply the digital extensor muscles. This nerve damage results in abnormal reflex arcs and disrupted coordination between flexor and extensor muscle groups, producing the characteristic hyperflexion. The lateral digital extensor muscle appears particularly vulnerable, and its dysfunction contributes significantly to the exaggerated limb movement. In idiopathic cases, the underlying neurological abnormality is less clear, with proposed mechanisms including spinal cord dysfunction, peripheral nerve abnormalities, and primary muscle disorders.

Early warning signs of stringhalt may be subtle and easily overlooked, particularly in mild cases or during the initial stages of Australian stringhalt development. Owners may first notice a slight hesitation or catch in the hindlimb stride that appears intermittently, especially when the horse is asked to back up, turn sharply, or walk after a period of rest. The horse may show reluctance to move forward freely or demonstrate mild coordination issues in the hindquarters. Because horses naturally mask discomfort and abnormalities as prey animals, early stringhalt signs often go unrecognized until the condition progresses to more obvious gait abnormalities. Careful observation during daily handling, turnout, and exercise helps identify developing problems before they become severe.

Common symptoms of established stringhalt include the hallmark exaggerated flexion of one or both hindlimbs during movement. The affected leg snaps upward toward the belly in an involuntary, often jerky motion that is distinctly different from normal hindlimb action. This hyperflexion varies in intensity from a slight exaggeration of normal movement to extreme flexion where the hoof may contact the abdomen before being thrust back toward the ground. The abnormal movement typically worsens when the horse is asked to back up, turn, or move from a standing position. Cold weather, excitement, and stress often exacerbate symptoms, while warming up through exercise may temporarily improve the gait in some cases.

Behavioral changes associated with stringhalt reflect both the physical difficulty of movement and potential frustration or discomfort. Affected horses may become reluctant to move, especially when first taken from the stall or asked to work. Some horses show signs of anxiety or agitation related to their inability to control limb movement normally. Appetite typically remains normal in stringhalt cases, distinguishing this condition from many other neurological disorders. Horses may develop compensatory movement patterns or demonstrate stiffness in other areas as they adapt to the abnormal hindlimb mechanics. Social interactions and herd dynamics may change if affected horses have difficulty keeping up with herd movement.

Physical signs beyond the characteristic gait include muscle changes that develop over time. In chronic cases, the affected hindlimb muscles may show atrophy, particularly in the lateral digital extensor and other muscles of the gaskin region. Conversely, some horses develop hypertrophy of compensating muscles as they adapt their movement patterns. The hindquarters may appear asymmetrical if only one limb is affected. Hoof wear patterns may change due to altered limb placement and movement, and horses may show difficulty maintaining proper hoof balance. Joint stress from the abnormal movement can lead to secondary swelling or stiffness in the hock and stifle regions.

Symptom progression varies significantly between the two forms of stringhalt. Australian stringhalt typically develops over days to weeks following toxic plant exposure, often affecting multiple horses on a property simultaneously. Initial mild signs rapidly progress to moderate or severe hyperflexion, then may stabilize or continue worsening depending on ongoing exposure. Idiopathic stringhalt often appears more suddenly in a single limb and may remain static or gradually worsen over time. Both forms can show fluctuation in severity based on environmental conditions, activity level, and time of day. Some horses experience spontaneous improvement while others show progressive deterioration.

Emergency symptoms requiring immediate veterinary care include sudden severe bilateral hindlimb dysfunction that prevents normal standing or walking, signs of distress or panic related to inability to move normally, concurrent neurological signs affecting other body regions suggesting a different or additional condition, and any sudden onset of severe gait abnormality in previously normal horses. While stringhalt itself is not typically life-threatening, severe cases significantly impact welfare and require urgent veterinary evaluation. Horses showing signs of colic, fever, or other systemic illness alongside gait abnormalities need immediate attention, as these findings suggest conditions other than simple stringhalt. Any horse that cannot rise or that falls repeatedly requires emergency veterinary assessment.

Physical examination for stringhalt begins with careful observation of the horse's gait at walk and, if possible, at trot. The veterinarian watches the horse move in hand on flat ground, in circles, backing up, and during transitions between gaits. The characteristic hyperflexion is usually readily apparent in moderate to severe cases, while mild cases may require provocative testing such as asking the horse to back up or turn sharply to elicit abnormal movement. The examiner notes which limb or limbs are affected, the severity and consistency of the hyperflexion, and any factors that worsen or improve the gait. A complete neurological examination assesses overall coordination, reflexes, and cranial nerve function to rule out other neurological conditions that might produce similar signs.

Diagnostic tests help characterize the condition and rule out other causes of hindlimb gait abnormalities. Blood work including a complete blood count and serum chemistry panel evaluates overall health status and screens for systemic disease. While no specific blood test diagnoses stringhalt, these baseline values help assess the horse's general condition and identify concurrent problems. Muscle enzyme levels may be elevated in some cases, reflecting ongoing muscle damage from the abnormal movement pattern. If Australian stringhalt is suspected, the veterinarian may recommend testing pasture samples for toxic plants and evaluating other horses on the property for similar signs.

Advanced diagnostics may be employed when the diagnosis is uncertain or when evaluating horses for potential surgical treatment. Electromyography (EMG) can detect abnormal electrical activity in affected muscles, providing objective evidence of neuromuscular dysfunction and helping localize the problem. Nerve conduction studies assess the function of peripheral nerves supplying the hindlimb. Ultrasound examination of the affected muscles and tendons may reveal structural changes, atrophy, or other abnormalities. In some cases, MRI of the spine or peripheral nerves helps rule out other conditions and provides detailed imaging of neural structures. Muscle biopsy, while rarely performed, can demonstrate the characteristic changes of distal axonopathy in Australian stringhalt cases.

Differential diagnosis for stringhalt includes several other conditions that produce abnormal hindlimb movement or gait. Shivers is a neuromuscular disorder that causes hindlimb hyperflexion similar to stringhalt but typically occurs when the horse is asked to back up or hold the limb elevated and includes muscle trembling. Fibrotic myopathy causes a characteristic slapping gait with mechanical restriction of limb movement rather than hyperflexion. Upward fixation of the patella produces intermittent hindlimb locking in extension rather than flexion. Equine protozoal myeloencephalitis and other spinal cord diseases can produce coordination deficits and gait abnormalities requiring differentiation from stringhalt. Peripheral nerve injuries, hock arthritis, and certain muscle disorders must also be considered. The veterinarian uses history, clinical examination, and diagnostic testing to distinguish stringhalt from these other conditions and develop an appropriate treatment plan.

Emergency and immediate treatment for severe stringhalt cases focuses on removing the inciting cause when possible and providing supportive care. For Australian stringhalt, the most critical intervention is immediately removing affected horses from contaminated pastures and eliminating access to toxic plants. This may require complete stall confinement or moving horses to a clean, weed-free pasture or drylot. Providing high-quality hay eliminates the need for horses to graze potentially contaminated vegetation. Supportive care including anti-inflammatory medications helps manage discomfort associated with the abnormal movement. Horses with severe bilateral involvement may require assistance with movement and careful management to prevent injury from falls or uncontrolled limb movement.

Medical management of stringhalt includes several pharmacological approaches with varying success rates. Phenytoin, an anticonvulsant medication, has shown efficacy in some stringhalt cases by reducing the involuntary muscle contractions responsible for hyperflexion. Treatment protocols typically involve oral phenytoin administration for several weeks, with gradual dose reduction once improvement is noted. Muscle relaxants such as methocarbamol may provide temporary symptomatic relief. Thiamine (vitamin B1) supplementation is sometimes recommended, particularly for Australian stringhalt cases where the plant toxins may interfere with thiamine metabolism. Non-steroidal anti-inflammatory drugs help manage any discomfort associated with the condition but do not address the underlying neuromuscular dysfunction.

Surgical options exist for cases that fail to respond to medical management or for idiopathic stringhalt affecting a single limb. Myotenectomy involves surgical removal of a portion of the lateral digital extensor muscle and tendon, eliminating the contribution of this dysfunctional structure to the abnormal gait. The surgery is performed under general anesthesia with the horse positioned in lateral recumbency, and the affected muscle and tendon are identified and resected through an incision over the lateral aspect of the affected hindlimb. Success rates for myotenectomy vary widely in published reports, ranging from 50% to over 80% improvement depending on case selection and severity. The procedure is generally most successful for unilateral idiopathic cases and less predictable for bilateral or Australian stringhalt.

Supportive care throughout stringhalt treatment includes maintaining appropriate nutrition to support nerve and muscle healing, providing comfortable housing that minimizes the need for difficult movements, and implementing careful exercise management. Physical therapy approaches such as controlled walking exercise, stretching, and massage may help maintain muscle condition and joint flexibility. Acupuncture has been used with anecdotal reports of improvement in some cases. Maintaining good hoof care prevents additional stress on the musculoskeletal system. Environmental management to reduce stress, avoid cold conditions that worsen symptoms, and provide safe footing supports overall recovery.

Rehabilitation and return to work protocols depend on the severity of the condition and response to treatment. Horses recovering from Australian stringhalt may gradually return to normal activity as clinical signs resolve, which can take weeks to months following removal from toxic pastures. Post-surgical cases require several weeks of stall rest followed by gradual reintroduction of exercise. The rehabilitation timeline must be individualized based on the degree of improvement achieved. Some horses return to full athletic function while others retain residual gait abnormalities that limit their use. Regular reassessment by the veterinarian guides the rehabilitation process and helps set realistic expectations for recovery.

Treatment decision factors include the form and severity of stringhalt, the horse's intended use, economic considerations, and response to initial conservative treatment. Australian stringhalt cases often warrant a trial of conservative management before considering surgery, as many improve significantly with pasture removal and time. Idiopathic cases may be candidates for earlier surgical intervention, particularly when affecting a single limb in a horse where normal gait is essential for intended use. Owner expectations must be managed carefully, as outcomes are variable and some horses fail to respond to any treatment. The potential for spontaneous improvement in some cases supports patience and conservative management when welfare is not immediately compromised.

Recovery timeline for stringhalt varies dramatically based on the form of the condition and the treatment approach employed. Australian stringhalt cases that are promptly removed from contaminated pastures may show initial improvement within two to four weeks, though complete recovery often requires three to twelve months or longer. The extended recovery period reflects the time required for damaged peripheral nerves to regenerate and for normal neuromuscular function to return. Some horses recover completely with no residual signs while others retain mild persistent abnormalities that do not significantly affect function. Idiopathic stringhalt cases have less predictable recovery patterns, with some remaining static indefinitely and others showing gradual improvement or progression regardless of treatment.

Post-treatment care and monitoring require ongoing attention to detect improvement or deterioration and to manage any complications. Regular gait evaluations document the progression of recovery and help determine when activity levels can be increased. For horses recovering from Australian stringhalt, continued avoidance of potentially contaminated pastures is essential, and owners must remain vigilant about pasture management and weed control. Post-surgical cases require careful incision monitoring, appropriate wound care, and adherence to prescribed rest periods. Serial video recordings of the horse's gait provide valuable documentation of recovery progress and help assess subtle changes that might not be apparent on day-to-day observation.

Prognosis factors affecting recovery include the severity of clinical signs at diagnosis, the specific form of stringhalt, how quickly treatment was initiated, and individual variation in healing capacity. Horses with mild to moderate Australian stringhalt that receive prompt treatment by removal from toxic pastures have good to excellent prognoses, with most achieving significant improvement or complete resolution. Severe bilateral cases carry more guarded prognoses, with some horses retaining permanent deficits. Idiopathic stringhalt outcomes are less predictable, with surgical success rates varying based on case selection and technique. Younger horses may have better regenerative capacity than older individuals, potentially influencing recovery outcomes.

Long-term soundness outlook depends on residual neurological function and the horse's intended use. Horses that achieve complete recovery from stringhalt can return to all previous activities including competitive athletics. Those with persistent mild abnormalities may function adequately for pleasure riding and lighter work while being unsuitable for disciplines requiring precise movement or high-level athletic performance. Some horses retain cosmetic gait abnormalities that do not affect their comfort or function. For breeding animals, the potential hereditary component of idiopathic stringhalt should be considered when making breeding decisions. Regular monitoring remains important, as some horses experience relapse of signs, particularly if re-exposed to toxic plants or during periods of stress.

Management practices form the cornerstone of stringhalt prevention, particularly for Australian stringhalt where pasture quality directly influences disease risk. Regular pasture inspection identifies toxic plants before they become established or widespread. Flatweed, the primary culprit in Australian stringhalt, is recognizable by its dandelion-like appearance with hairy leaves forming a basal rosette and yellow flowers on long stems. Prompt removal of toxic plants by hand-pulling, targeted herbicide application, or mowing before seed set reduces exposure risk. Maintaining healthy, dense pasture growth through appropriate fertilization, irrigation, and grazing management helps competitive grasses crowd out toxic weed species. Rotational grazing prevents overgrazing that allows weedy species to establish.

Nutritional prevention supports overall neuromuscular health and may reduce susceptibility to stringhalt-causing toxins. Providing adequate high-quality forage reduces horses' tendency to graze undesirable plants. Supplemental feeding during periods of poor pasture quality, particularly during drought or at the end of the growing season when toxic plants may be most prevalent, decreases reliance on potentially contaminated grazing. Ensuring adequate vitamin and mineral intake supports nerve and muscle function. While no specific nutritional intervention is proven to prevent stringhalt, maintaining optimal nutritional status supports the horse's ability to detoxify ingested compounds and recover from toxic insults.

Exercise and conditioning considerations relate more to management of affected horses than to primary prevention, as stringhalt is not caused by exercise factors. However, maintaining overall fitness and musculoskeletal health may support more rapid recovery should stringhalt develop. Regular exercise promotes good circulation and neuromuscular function. Horses in good physical condition may tolerate the physical demands of abnormal movement better than unconditioned animals. For horses recovered from stringhalt, gradual return to conditioning helps rebuild strength without overloading healing tissues.

Environmental factors including pasture type, geographic location, and seasonal conditions significantly influence stringhalt risk. Properties in regions with high prevalence of flatweed or other toxic plants require particular vigilance. Establishing pastures with improved grass species and maintaining appropriate soil fertility discourages weed invasion. During high-risk seasons, typically late summer through autumn, increased monitoring and possible restriction of pasture access may be warranted. Providing alternative forage sources such as hay when pasture quality declines reduces grazing of potentially toxic plants. Climate conditions that favor toxic plant growth, particularly drought followed by rain, should prompt increased surveillance.

Vaccination and deworming protocols do not directly prevent stringhalt but contribute to overall equine health management. Maintaining routine preventive care ensures horses are in optimal condition to resist disease challenges. While no vaccine exists for stringhalt, comprehensive health management reduces concurrent stressors that might influence disease expression or recovery. Regular veterinary examinations provide opportunities to detect early signs of stringhalt or other conditions. Documentation of any stringhalt cases on a property helps inform future prevention strategies and alerts veterinarians to monitor other horses for similar signs.

Daily management adjustments for horses with stringhalt focus on accommodating their movement limitations while maintaining quality of life. Stall design should allow easy entry and exit without sharp turns that exacerbate hyperflexion. Deep, supportive bedding cushions limbs during the exaggerated foot placement. Water and feed containers positioned at comfortable heights reduce difficult movements. Daily routines should be consistent to minimize stress that can worsen symptoms. Handler patience is essential, as affected horses may require extra time for movements that are simple for normal horses. Avoiding situations that trigger severe hyperflexion, such as sudden backing requests or sharp turns, reduces both physical strain and emotional stress.

Housing and turnout considerations balance the benefits of movement and socialization against safety concerns related to abnormal gait. Flat, even footing minimizes stumbling and reduces stress on joints subjected to abnormal forces. Small turnout areas may be preferable initially to prevent excessive movement that could cause fatigue or injury. Gradual increase in turnout space as the horse adapts to its condition allows safe expansion of activity. Turnout companions should be selected carefully to avoid aggressive interactions that might require rapid movement. Shelter access protects against cold weather that typically worsens stringhalt signs. Surface conditions during wet weather require attention, as slippery footing poses increased risk for horses with coordination deficits.

Exercise modifications must be tailored to the individual horse's severity of signs and intended use. Mild cases may tolerate normal light exercise with minimal accommodation. Moderate to severe cases benefit from limited, controlled exercise on flat, consistent footing. Walking exercise often improves with warm-up, so allowing adequate time for the horse to loosen up before asking for more demanding work is beneficial. Arena work on good footing provides controlled conditions for exercise. Trail riding may be inappropriate for horses with severe signs due to terrain challenges. Some horses function better under saddle than in hand, as the rider's weight and balance may stabilize the hindquarter movement.

Monitoring and ongoing care include regular gait assessment to track the condition's progression or improvement. Video documentation at regular intervals provides objective records of gait quality over time. Body condition monitoring ensures the horse maintains appropriate weight despite any exercise limitations. Regular hoof care maintains proper balance and reduces secondary strain on limbs. Observation for secondary problems such as muscle soreness, joint swelling, or hoof abnormalities allows early intervention. Communication with the veterinarian about any changes in the condition guides treatment adjustments and management modifications.

Quality of life and use considerations require honest assessment of the horse's comfort and functional capacity. Horses with mild residual stringhalt often enjoy excellent quality of life and can participate in many activities. Those with moderate signs may be suitable for light pleasure riding or serve as companion animals. Severe persistent cases require careful evaluation of ongoing welfare. Career changes may be necessary for performance horses that cannot return to their previous discipline. Retirement to a comfortable pasture environment may be appropriate for horses whose signs prevent athletic use but allow reasonable quality of life. Euthanasia should be considered when severe signs persist despite treatment and significantly compromise the horse's welfare.

Stringhalt affects horses of all breeds without strong breed predisposition, distinguishing it from many other equine conditions that show clear breed associations. Australian stringhalt in particular demonstrates no breed preference, affecting any horse exposed to toxic pastures regardless of breeding. Reports include affected Thoroughbreds, Quarter Horses, Arabians, Warmbloods, ponies, and draft breeds in equal measure when grazing contaminated pastures. This equal susceptibility across breeds suggests that the primary risk factor is environmental exposure rather than genetic predisposition. Individual variation in susceptibility within any breed appears more significant than between-breed differences.

Use and discipline considerations influence both exposure risk and the impact of stringhalt on affected horses. Horses maintained primarily on pasture face higher exposure risk to Australian stringhalt compared to those kept in stalls with minimal grazing access. Working ranch horses, pleasure horses, and breeding stock turned out on extensive pastures may encounter toxic plants more frequently than intensively managed competition horses. However, the impact of stringhalt on function is often greatest for horses in disciplines requiring precise hindquarter engagement, such as dressage, reining, and cutting. Draft horses used for driving may have their work capacity compromised by severe hindlimb dysfunction. Racehorses' careers may be significantly impacted even by mild gait abnormalities.

Genetic testing for stringhalt susceptibility is not currently available, and breeding recommendations remain based on general principles rather than specific genetic guidance. Because idiopathic stringhalt may have a hereditary component, some authorities recommend against breeding horses that develop this form of the condition, particularly those with a family history of similar signs. For Australian stringhalt, the environmental etiology means affected horses can generally be bred without genetic concerns about transmitting the condition. However, individual susceptibility to plant toxins may have a genetic basis, creating uncertainty about breeding decisions for recovered Australian stringhalt cases. Purchasing horses from properties with history of stringhalt outbreaks warrants careful veterinary examination and awareness of ongoing risk.

Commonly co-occurring conditions with stringhalt include secondary musculoskeletal problems that develop as a consequence of abnormal movement patterns. Muscle fatigue and soreness affect horses dealing with constant hyperflexion of the hindlimbs. Joint stress, particularly in the hock and stifle, can lead to inflammation or degenerative changes over time. Hoof imbalance may develop from altered limb placement and wear patterns. Horses with stringhalt may be more prone to injuries from stumbling or falling, particularly when navigating uneven terrain or during episodes of severe hyperflexion. In Australian stringhalt outbreaks, multiple horses on the same property may be affected simultaneously, though this represents shared exposure rather than true co-occurrence of distinct conditions.

Conditions with similar symptoms require careful differentiation from stringhalt to ensure appropriate treatment. Shivers presents with hindlimb hyperflexion similar to stringhalt but includes characteristic muscle trembling and typically occurs when the horse is asked to hold the limb elevated or back up. Fibrotic myopathy causes mechanical gait restriction from scar tissue rather than neuromuscular dysfunction, producing a slapping gait rather than hyperflexion. Upward fixation of the patella causes intermittent hindlimb locking in extension with sudden release. Equine protozoal myeloencephalitis and other spinal cord diseases can produce hindlimb coordination deficits. Peripheral nerve injuries may cause focal muscle dysfunction affecting gait. Hock pain from arthritis or other conditions can alter hindlimb movement.

Potential complications of stringhalt include physical injury from falls or stumbling, chronic musculoskeletal strain from abnormal movement, and psychological stress related to movement dysfunction. Horses with severe bilateral stringhalt may develop pressure sores from difficulty rising if they become recumbent. Secondary lameness from joint or soft tissue stress compounds the primary gait abnormality. In some cases, stringhalt may be complicated by other neurological conditions that develop concurrently or were present but undiagnosed prior to stringhalt onset. Weight loss can occur in severely affected horses due to the metabolic demands of abnormal movement and potential difficulty accessing food and water. Appropriate management minimizes complication risk and supports the best possible quality of life.