Signs of Neurological Abnormalities in Horses: Symptoms & Associated Conditions

Neurological signs in horses are observable changes that suggest the brain, spinal cord, or nerves are no longer coordinating normal movement, sensation, behavior, or awareness. These signs can range from subtle changes in performance to a sudden loss of strength or balance, potentially creating a serious safety risk for the horse and nearby handlers.

Stumbling, weakness, unusual behavior, and difficulty controlling movement may indicate nervous system dysfunction, but these signs are not specific to a single condition. They can also resemble lameness, pain, or muscle disorders, making prompt veterinary evaluation essential.

A veterinarian can assess the pattern and progression of abnormalities to help determine where the problem is occurring and which diagnostic tests are appropriate. The underlying cause, severity, and response to treatment ultimately shape management and prognosis.

Keep reading to learn how to recognize neurological concerns in horses, what to expect from veterinary evaluation, and how affected horses can be managed safely.

Neurological Signs in Horses

Neurological signs in horses are abnormalities in movement, behavior, sensation, or muscle function that occur when the nervous system is not operating normally.

The nervous system includes the brain, spinal cord, peripheral nerves, and connections between nerves and muscles that control movement and other bodily functions. ^[1]

The type and severity of neurological signs depend on which part of the nervous system is affected. Some horses develop subtle changes, such as stumbling, an altered gait, or reduced performance, while others may show pronounced weakness, incoordination, seizures, or difficulty standing. ^[2][3][4]

Owners may have difficulty recognizing neurological problems because their signs may resemble: ^[3][5][6]

• Lameness
• Pain
• Muscle disorders
• Behavioral changes

A veterinary neurological examination helps determine whether the abnormality is neurological and identify which area of the nervous system may be involved.

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Patterns of Neurological Abnormalities

Veterinarians evaluate not only which neurological signs are present but also how those signs are distributed throughout the horse’s body. These patterns can provide clues about which part of the nervous system is affected. ^[4]

For example, abnormalities may primarily involve the hind limbs, affect all four limbs, occur predominantly on one side, or appear relatively symmetrical. Other horses may show more localized abnormalities involving the face, an individual limb, or a specific group of muscles. ^[3][4]

Changes in behavior, awareness, vision, or cranial nerve function can suggest involvement of the brain or associated nerves. In contrast, patterns of weakness and incoordination affecting the limbs may point toward the spinal cord or peripheral nervous system. ^[3][4][7]

These patterns are not specific enough for owners to diagnose the location or cause of neurological disease themselves. However, identifying the distribution of abnormalities during a veterinary examination helps guide localization and further diagnostic testing. ^[8]

Neurological Signs vs. Lameness

Neurological dysfunction and orthopedic lameness can produce similar changes in a horse’s movement, including: ^[5]

• Stumbling
• Shortened strides
• Unusual limb movement
• Reluctance to move
• Decreased athletic performance

Lameness generally results from pain or mechanical dysfunction involving the musculoskeletal system. Neurological abnormalities instead result from impaired control of movement, balance, sensation, or strength. ^[9]

Neurological dysfunction may be more likely when abnormalities involve multiple limbs, foot placement is inconsistent, weakness occurs without an obviously painful limb, or additional signs such as altered mentation or cranial nerve abnormalities are present. ^[6][10]

However, horses can have neurological and orthopedic conditions at the same time, and mild neurological disease can be particularly difficult to distinguish from musculoskeletal problems. ^[6][9]

Owners should not intentionally place an unstable horse in difficult positions or attempt potentially dangerous neurological tests themselves. A veterinarian can perform appropriate assessments while minimizing risk to the horse and handlers. ^[4][6]

Table 1. Differences between neurological signs and lameness in horses

Clinical Signs of Neurological Disease in Horses

Clinical signs of neurological disease vary depending on the location, severity, and underlying cause of nervous system dysfunction. Some horses show obvious abnormalities, while others initially present with subtle changes in gait, performance, or behavior. ^[2][11]

Ataxia & Incoordination

Ataxia refers to a lack of normal coordination during movement. An ataxic horse may know where they want to place their limbs but have difficulty controlling limb movement and position accurately. ^[12]

Affected horses may sway or appear unstable while standing or walking. Their foot placement can be irregular or inconsistent, and they may cross their limbs, drag their toes, or stumble. They may also swing a limb outward or drift or lean to one side. ^[2]

Neurological gait abnormalities often become more apparent during movements that require greater coordination. For example, an ataxic horse may have increased difficulty backing or making tight turns, particularly when walking on slopes. ^[4][12]

Ataxia can sometimes resemble lameness, but it reflects impaired control of movement rather than a problem originating solely within the musculoskeletal system. ^[3]

Weakness & Paresis

Paresis describes a partial loss of voluntary movement or muscle strength caused by neurological dysfunction. ^[1][3]

Affected horses may have difficulty supporting their body weight or generating normal movement. The knees or fetlocks may buckle, the toes may drag, or the horse may knuckle over while bearing weight. ^[1][3]

Weakness can also make it difficult to back, rise from the ground, maintain balance, or shift weight normally. Severely affected horses may become recumbent and unable to stand without assistance. ^[1][3]

Changes in Behavior & Mentation

The brain regulates awareness, behavior, and responses to the horse’s environment. Given this, diseases affecting the brain can cause changes in mentation, or the horse’s level of awareness and mental responsiveness. ^[3][7]

A horse with altered mentation may appear unusually dull or unresponsive, show reduced awareness of their surroundings, or become unexpectedly agitated or excitable. More pronounced abnormalities can include compulsive walking, circling, head pressing, or seizures, as well as unusual responses to familiar people and surroundings. ^[1]

Behavioral changes are not always neurological. Pain, illness, stress, and environmental factors can also alter a horse’s behavior. However, sudden or significant changes in mentation warrant veterinary assessment, particularly when accompanied by other neurological abnormalities. ^[2][3]

Cranial Nerve Abnormalities

The cranial nerves control functions involving the face, eyes, ears, tongue, and throat. Dysfunction of these nerves can produce distinctive clinical signs affecting facial movement, sensation, vision, chewing, and swallowing. ^[7]

Affected horses may develop facial asymmetry or drooping of an ear, eyelid, or lip. Other abnormalities can include reduced facial movement or sensation, abnormal tongue movement, a head tilt, changes in eye position or movement, and impaired vision. ^[3][7]

Cranial nerve dysfunction can also interfere with eating and swallowing. Horses may drop feed while chewing or have difficulty moving food and water normally through the throat. ^[2][7] Difficulty swallowing (dysphagia) is particularly concerning because affected horses may inhale feed or water into the respiratory tract. ^[2][7]

Tremors, Twitching & Abnormal Muscle Activity

Abnormal muscle activity can occur when disease affects the brain, spinal cord, peripheral nerves, neuromuscular junction, muscles, or metabolism. ^[13][14] These signs may be intermittent or continuous and can range from mild trembling to severe uncontrolled movement.

Possible signs include: ^[13][10][14]

• Muscle trembling or shaking
• Localized twitching or fasciculations
• Rigid or unusually stiff muscles
• Episodes of uncontrolled muscle movement
• Weakness that worsens with activity
• Difficulty chewing, swallowing, standing, or moving normally

Tremors and twitching are not specific to one diagnosis. They may occur with neurological disease, neuromuscular disorders, toxic exposures, electrolyte disturbances, pain, anxiety, or systemic illness. ^[14][15][16]

Veterinary assessment is necessary when abnormal muscle activity is persistent, severe, worsening, associated with weakness or incoordination, or accompanied by changes in behavior, appetite, swallowing, or awareness.

Seizures, Collapse & Loss of Consciousness

Seizures occur when abnormal electrical activity in the brain disrupts normal awareness, movement, or behavior. ^[17] In horses, seizures may be dramatic and easy to recognize, or they may appear as a sudden episode of collapse, abnormal behavior, or loss of awareness. ^[18]

Possible signs of a seizure or seizure-like episode include: ^[18]

• Sudden collapse or falling
• Loss of awareness or reduced responsiveness
• Uncontrolled paddling, thrashing, or limb movements
• Muscle rigidity, trembling, or twitching
• Abnormal chewing motions, facial movements, or salivation
• Temporary blindness, confusion, dullness, or agitation after the episode

Not every horse that collapses is having a seizure. Collapse or loss of consciousness can also occur with cardiovascular disease, severe metabolic disturbance, toxicity, trauma, shock, or other medical emergencies. ^[18][19] Any horse that collapses, loses awareness, has a seizure, or cannot rise safely requires immediate veterinary assessment. ^[19]

Vision Changes & Blindness

Vision changes can occur with disease affecting the eye, optic nerve, brain, or other parts of the nervous system. Because horses rely heavily on vision for movement, balance, and safety, sudden or progressive visual impairment can create a serious risk for the horse and handlers. ^[10][21]

Signs that may suggest impaired vision include: ^[10][22]

• Bumping into fences, doors, feeders, or other objects
• Reluctance to move forward, especially in unfamiliar areas
• Exaggerated startle responses when approached from one side
• Difficulty navigating changes in light, shadows, or uneven footing
• Sudden anxiety, spooking, or hesitation in familiar environments
• Abnormal eye position, pupil size, or response to nearby movement

Vision loss is not always caused by cranial nerve dysfunction. Eye disease, trauma, inflammation, retinal disease, optic nerve damage, brain disease, and some infectious or toxic conditions can all affect vision. ^[10][21]

Head Tilt, Circling & Balance Problems

A head tilt, circling, leaning, drifting, or loss of balance may indicate dysfunction in the vestibular system, brain, cranial nerves, or other neurological pathways involved in orientation and coordination. These signs can make the horse unstable and increase the risk of falling. ^[10]

Possible signs include: ^[10][23]

• Persistent head tilt or abnormal head position
• Circling, wandering, or repeatedly turning in one direction
• Leaning against walls, fences, or handlers
• Loss of balance or falling to one side
• Abnormal rhythmic eye movements
• Anxiety or reluctance to move
• Difficulty standing squarely or walking in a straight line

These signs can overlap with pain, trauma, or severe systemic illness. A horse with head tilt, circling, abnormal eye movements, or worsening balance should be examined by a veterinarian. ^[2][10]

Abnormal Sensation & Limb Awareness

Neurological disease can interfere with the horse’s ability to sense limb position, pressure, pain, or touch. This can affect how the horse places their feet and responds to changes in footing, even when muscle strength appears relatively normal. ^[10]

Signs of abnormal limb awareness or sensation may include: ^[10]

• Dragging the toes or scuffing the hoof wall
• Crossing the limbs or placing the feet too close together
• Misjudging steps, poles, uneven ground, or stall thresholds
• Reduced response to touch, pressure, or stimulation in a specific area

Owners should not attempt neurological placement tests. Manual limb-placement testing is not considered a reliable assessment of proprioception in horses. A veterinarian can evaluate sensation, posture, gait, coordination, and strength using appropriate examination techniques. ^[10]

Tail, Bladder & Bowel Abnormalities

Some neurological disorders affect the nerves that control the tail, anus, bladder, or hindquarter region. These signs may occur with spinal cord disease, sacral nerve dysfunction, trauma, or other conditions affecting the lower nervous system. ^[10]

Possible signs include: ^[10][24][25]

• Reduced tail tone or an unusually limp tail
• Reduced sensation around the tail, hindquarters, or perineal area
• Difficulty urinating or dribbling urine
• Loss of normal bladder control
• Difficulty passing manure or loss of normal anal tone
• Manure or urine scalding around the hind limbs or tail area

Changes in urination or defecation are not always neurological, but they should not be ignored. A horse with bladder or bowel changes, hind limb weakness, tail tone abnormalities, or loss of sensation needs veterinary evaluation to determine whether the nervous system, urinary tract, digestive tract, or another body system is involved. ^[10][25]

Causes of Neurological Signs in Horses

Neurological signs are not a diagnosis. They can develop when disease, injury, or toxic exposure disrupts the function of the brain, spinal cord, peripheral nerves, or neuromuscular system.

Because different conditions can produce similar clinical signs, identifying the underlying cause typically requires a veterinary examination and targeted diagnostic testing. ^[26]

Infectious & Inflammatory Diseases

Infectious and inflammatory conditions can affect the brain, spinal cord, or surrounding tissues. Although these diseases may produce similar neurological abnormalities, their causes, transmission patterns, and biosecurity implications differ.  ^[1][5]

These conditions include: ^{[11][27][28][29][30]}

• Equine protozoal myeloencephalitis (EPM): This neurological disease occurs when a protozoal infection affects the brain or spinal cord. The presentation varies depending on the areas involved, and signs may include ataxia, weakness, muscle wasting, or other neurological deficits.
• West Nile virus: This mosquito-borne viral disease can affect the central nervous system. Affected horses may develop weakness, ataxia, muscle tremors, or changes in behavior and awareness.
• Equine herpesvirus myeloencephalopathy (EHM): Known as the neurological form of equine herpesvirus-1 (EHV-1) infection, EHM can affect the spinal cord and cause neurological deficits ranging from mild incoordination to severe weakness, recumbency, or an inability to stand.
• Eastern and Western equine encephalitis: These mosquito-borne viral diseases cause inflammation of the brain. Affected horses may develop substantial changes in coordination, strength, behavior, or awareness.
• Encephalitis and meningitis: Encephalitis refers to inflammation of the brain, while meningitis affects the membranes surrounding the brain and spinal cord. These conditions can arise from infectious or inflammatory processes and may cause a range of neurological signs.

Clinical signs alone are rarely enough to identify a specific infectious or inflammatory disease because several conditions can produce similar abnormalities. The horse’s history, vaccination status, recent travel, exposure to other horses, and the presence of fever or illness in other horses can help guide the veterinary investigation. ^[11]

Some infectious neurological diseases also carry herd-level biosecurity concerns. If a horse develops fever together with neurological signs, or if multiple horses on the property are affected, contact a veterinarian promptly. When it is safe to do so, separate the affected horse from others and follow veterinary instructions regarding isolation, handling, and movement. ^[31]

Spinal Cord Compression & Injury

Compression or injury of the spinal cord can disrupt communication between the brain and limbs, affecting the horse’s strength, balance, and coordination. ^[2][4]

Cervical vertebral stenotic myelopathy (CVSM), commonly called wobbler syndrome, involves narrowing of the cervical vertebral canal and compression of the spinal cord. Affected horses commonly show ataxia and weakness, although the severity and distribution of signs can vary. ^[32]

Trauma, vertebral abnormalities, and certain degenerative changes may also compress or damage the spinal cord. The resulting abnormalities depend on the location and extent of the injury. ^[1]

Toxic Causes

Certain toxins can disrupt nerve signaling and cause severe neurological or neuromuscular abnormalities. ^[33]

Botulism is caused by toxins produced by Clostridium botulinum. These toxins interfere with communication between nerves and muscles, leading to progressive weakness. Affected horses may also develop difficulty swallowing, recumbency, and respiratory failure. ^[33]

Toxic plants, contaminated feed, and other harmful substances can also affect the nervous system. Signs vary with the substance involved, amount consumed, and degree of exposure. They may include weakness, tremors, incoordination, or altered behavior, as well as other neurological abnormalities. ^[34]

Metabolic & Nutritional Causes

Severe metabolic disturbances can interfere with normal brain, nerve, and muscle function. Electrolyte imbalances and other systemic abnormalities may contribute to weakness, tremors, altered mentation, or abnormal movement. ^[6]

Nutritional deficiencies or imbalances can also affect nervous or muscular function in some circumstances. However, unexplained neurological signs should not automatically be attributed to nutrition because similar abnormalities occur with many infectious, toxic, traumatic, and structural conditions. ^[35]

A veterinary examination, bloodwork, and assessment of the complete diet may be appropriate when a metabolic or nutritional problem is suspected. ^[3][6]

Peripheral Nerve & Neuromuscular Disorders

Damage to individual peripheral nerves can affect specific muscles or regions of the body. Nerve injury may occur following trauma, prolonged pressure, or other disease processes. ^[1]

Depending on the nerve involved, affected horses may develop localized weakness, reduced muscle function, abnormal posture, altered sensation, or muscle wasting. ^[3][13]

Disorders of the neuromuscular junction interfere with communication between nerves and muscles. This can result in generalized or progressive weakness even when the brain and spinal cord are functioning normally. ^[13][33]

Diagnosing Neurological Issues in Horses

Diagnosing neurological disease begins with determining whether the horse’s signs involve the nervous system. The veterinarian then works to identify the affected region and investigate the underlying cause. ^[3]

The diagnostic process typically begins with a detailed medical history and general physical examination. ^[6][10]

The veterinarian will ask when the signs first appeared, whether they developed suddenly or gradually, and whether they have remained stable or worsened. Important clues in a horse’s history may include: ^[2][26][31]

• Recent fever
• Illness
• Travel
• Contact with new horses
• Vaccination history
• Previous trauma

Other relevant information includes recent dietary changes, possible exposure to toxins, and whether other horses on the property are showing similar signs. Videos of the horse’s abnormal movement can also be helpful, particularly when signs are intermittent or more noticeable under specific circumstances. ^[5]

Neurological Examination

If neurological dysfunction is suspected, the veterinarian will evaluate different components of the horse’s nervous system through a structured neurological examination. ^[6][10]

The examination may include an assessment of mental status and behavior, cranial nerve function, muscle symmetry and tone, gait, coordination, limb placement, and strength. Depending on the horse’s condition, the veterinarian may also evaluate tail tone and responses to controlled movement. ^[10]

The veterinarian also considers where the abnormalities appear. Signs may affect: ^[3]

• One side of the body
• Both hind limbs
• All four limbs
• The cranial nerves
• One localized muscle group

Each pattern can provide different information about where nervous system dysfunction may be occurring. ^[3]

Together, these findings help the veterinarian identify the region of the nervous system most likely to be affected. Localization helps distinguish possible involvement of the brain, spinal cord, peripheral nerves, or neuromuscular system and guides the selection of diagnostic tests. ^[3][4]

Diagnostic Testing

Once the neurological abnormality has been localized, the veterinarian can select diagnostic tests based on the suspected cause and affected region. ^[1]

Bloodwork may be used to evaluate the horse’s general health and identify metabolic abnormalities or evidence of infection. Specific infectious disease testing may also be recommended when conditions such as EPM, West Nile virus, or EHV-1 are suspected. ^[26][27][28]

Cerebrospinal fluid analysis can provide further information about inflammation or disease affecting the central nervous system. Diagnostic imaging may include radiographs (x-rays) or ultrasound, while computed tomography (CT) or magnetic resonance imaging (MRI) may be appropriate in some cases. ^[1][8][36]

Not every affected horse requires every test. The diagnostic plan is tailored to the examination findings, suspected location of the neurological abnormality, and conditions considered most likely. ^[6][10][36]

When Neurological Signs Are an Emergency

Neurological abnormalities can worsen rapidly, and severely affected horses may pose a safety risk to themselves and nearby handlers. ^[5][26]

Contact a veterinarian promptly if a horse develops: ^[6][31][33]

• Sudden loss of coordination
• Rapidly worsening ataxia
• Repeated falling
• Inability to stand
• Severe weakness
• Seizures
• Difficulty swallowing
• Sudden blindness or other changes in vision
• Major changes in awareness or behavior
• Fever accompanied by neurological abnormalities
• Neurological signs affecting multiple horses

A severely ataxic horse can fall or move unpredictably. Avoid forcing an unstable horse to walk or attempting neurological tests while waiting for veterinary guidance. ^[12]

If fever accompanies neurological abnormalities or more than one horse is affected, an infectious cause may be possible. Follow veterinary instructions regarding isolation and biosecurity while minimizing unnecessary movement of the affected horse. ^[26][28][31]

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Managing a Horse with Neurological Signs

Management depends on the underlying diagnosis and severity of the horse’s neurological deficits. While veterinary assessment and treatment are underway, the immediate priority is preventing injury to the horse and nearby handlers. ^[2][6]

An unstable horse may require restricted movement, secure footing, appropriate bedding, and an environment free from obstacles that could increase the risk of falling or becoming trapped. Feed and water should be placed where the horse can reach them without unnecessary movement. ^[2][6]

Horses with difficulty chewing or swallowing require prompt veterinary guidance because of the risk of inhaling feed or water into the respiratory tract. Handlers should also use caution around horses with severe weakness or ataxia, as affected horses may lose balance or move unpredictably. ^{[2][6][12][32]}

If an infectious disease is suspected, veterinarians may recommend isolation and additional biosecurity measures to reduce potential transmission between horses. ^[28][31]

Throughout the horse’s care, monitor coordination, strength, appetite, swallowing, behavior, and ability to stand. Report any deterioration promptly to the veterinarian. ^[6][10]

Prognosis for Neurological Disease in Horses

The prognosis for a horse showing neurological signs depends on the underlying condition, the location and severity of nervous system damage, and the response to treatment. ^[2][6][11]

Some horses recover completely, while others retain mild or significant neurological deficits. The amount of improvement possible varies considerably among diseases and individual horses. ^[6][11][33] Severe or persistent deficits may affect a horse’s long-term welfare and their ability to safely return to riding or other athletic activities. ^[5][6][12]

Ongoing veterinary assessment is important when determining prognosis and whether a recovering horse can safely resume exercise. ^[6][10]

Nutrition & Neurological Health

Balanced nutrition supports normal nerve and muscle function, overall health, body condition, and recovery. Horses require adequate energy, protein, vitamins, minerals, and electrolytes to maintain these functions. ^[35][37] Nutrition can support general health and recovery, but it cannot replace veterinary diagnosis or treatment. ^[6][35]

Nutritional deficiencies or imbalances can contribute to weakness, tremors, poor muscle function, or other abnormalities in some circumstances. However, these signs are not specific to nutrient deficiencies and may also occur with infectious disease, spinal cord disorders, toxins, trauma, or other medical conditions. ^[35][38]

A veterinarian may recommend bloodwork, feed analysis, or a review of the horse’s complete diet when a nutritional or metabolic problem is suspected. Owners should avoid adding multiple supplements without professional guidance, as excessive or unbalanced nutrient intake can create additional health risks. ^[35][37][38]

For horses recovering from neurological illness, an equine nutritionist can help ensure the diet supports appropriate body condition and muscle maintenance. Any feeding plan must also account for the horse’s ability to chew and swallow safely. ^[6][37]

Frequently Asked Questions

Here are some frequently asked questions about neurological signs in horses:

Summary

Neurological signs in horses can affect movement, strength, sensation, behavior, and awareness. Prompt veterinary evaluation is essential because several conditions can cause similar abnormalities.

• Ataxia may cause swaying, stumbling, irregular foot placement, or difficulty backing and turning
• Weakness, altered mentation, seizures, and difficulty swallowing can indicate nervous system dysfunction
• Causes include infectious disease, spinal cord compression, toxins, and peripheral nerve disorders
• A neurological examination evaluates behavior, cranial nerves, gait, coordination, strength, and muscle function
• Sudden or worsening signs require prompt veterinary attention, especially if the horse cannot stand or swallow
• Management prioritizes secure footing, restricted movement, careful monitoring, and handler safety