Incoordination (Ataxia) in Horses: Related Signs, Causes & Management

Ataxia in horses refers to a loss of coordination and is one of the most common signs of neurological disease.

Affected horses may appear unsteady, place their feet inaccurately, stumble, or have difficulty maintaining balance. Severity ranges from subtle abnormalities to profound incoordination that affects everyday movement, performance, and safety.

Because normal movement depends on the coordinated function of the brain, spinal cord, peripheral nerves, and balance systems, many diseases and injuries can result in ataxia. Common causes in horses include equine protozoal myeloencephalitis (EPM), Wobbler syndrome, and equine herpesvirus myeloencephalopathy (EHM). Other cases may be linked to trauma, toxin exposure, viral infections, or degenerative disorders of the nervous system.

Ataxia can have serious implications for both horse welfare and rider safety. Understanding how coordination is controlled, what conditions can disrupt it, and the signs that may accompany ataxia can help horse owners recognize this important clinical sign and seek appropriate veterinary care.

What is Ataxia in Horses?

Ataxia in horses is a neurologic clinical sign characterized by impaired coordination of movement and difficulty controlling the position and placement of the limbs. ^[1][2] Horses with ataxia may appear unsteady, stumble, sway, drag their toes, cross their limbs, or place their feet inaccurately while moving. ^[1][3]

Ataxia occurs when disease or injury affects the parts of the nervous system responsible for balance, coordination, or awareness of body position. The severity can range from subtle abnormalities to severe incoordination that creates a risk of falling. ^[2][3][4][5]

For horses with ataxia, identifying the underlying cause is an important part of neurological evaluation, diagnosis, and treatment. ^[1][2]

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The Nervous System & Balance

Normal balance and coordination depend on the brain, spinal cord, and peripheral nerves working together to control movement and monitor body position. ^[2][3] These structures form the nervous system, which continuously receives information from the body and sends signals that help coordinate posture and movement. ^[2][4]

Damage affecting any of these structures can interfere with normal coordination and lead to ataxia. ^[1][2][5] The location of the underlying problem often influences how the ataxia appears and what other neurological signs may be present. ^[1][3]

Equine Coordination

Normal coordination depends on the nervous system constantly gathering information about body position and using that information to guide movement. ^[2][5] Specialized sensory receptors in muscles, tendons, and joints detect the position and movement of the limbs and send this information to the spinal cord and brain. ^[1][2]

The brain and spinal cord process these signals and generate responses that help maintain balance, posture, and coordinated movement. ^[2][5] As a horse walks, countless adjustments are made automatically to ensure that each limb is placed accurately and that the body remains stable. ^[2][5]

Within the brain, the cerebellum helps fine-tune movement, while the vestibular system helps maintain balance and orientation. ^[1][5] The spinal cord carries information between the brain and limbs, allowing movement to remain smooth and coordinated. ^[2][3]

When these pathways function normally, movement appears smooth, balanced, and coordinated. ^[1][5] When disease or injury disrupts the flow of information within the nervous system, the horse may lose the ability to accurately control limb placement and coordination, resulting in ataxia. ^[1][2]

Causes of Ataxia in Horses

A wide range of conditions affecting the brain, spinal cord, or systems involved in balance and coordination can interfere with normal movement and result in ataxia. ^[2][5] Some causes develop gradually, while others may appear suddenly after infection, injury, toxin exposure, or vascular damage.

Equine Protozoal Myeloencephalitis (EPM)

Equine protozoal myeloencephalitis is one of the most common neurological diseases affecting horses in North America. ^[2][6] The disease occurs when protozoan parasites damage the brain, spinal cord, or both. A distinguishing feature of EPM is that neurological deficits are often asymmetrical. ^[2][6]

Signs can vary widely depending on which areas of the nervous system are affected. Some horses may show mild incoordination, while others develop muscle loss, weakness, abnormal gait patterns, or more obvious neurological deficits. ^[2][6]

Cervical Vertebral Stenotic Myelopathy (Wobbler Syndrome)

Wobbler syndrome occurs when abnormalities of the neck vertebrae compress the spinal cord. ^[2][6] This compression disrupts communication between the brain and limbs. ^[2] The condition typically produces symmetrical ataxia. ^[1][6]

Affected horses may appear unsteady, especially when turning, backing, walking on uneven ground, or moving on a slope. The condition most commonly affects young, rapidly growing foals, but it can develop later in life. ^[1][6]

Equine Herpesvirus Myeloencephalopathy (EHM)

Equine herpesvirus myeloencephalopathy is a neurological form of infection caused by Equine Herpesvirus Type 1 (EHV-1). ^[2][7] The disease damages blood vessels within the spinal cord and brain, leading to neurological dysfunction. ^[6][7] Cases may occur individually or as part of an infectious disease outbreak. ^[7]

Horses with EHM may develop fever, weakness, hindlimb ataxia, urine dribbling, or difficulty rising. Because EHM can spread between horses, suspected cases require prompt veterinary attention, isolation, and biosecurity measures.

Eastern, Western, and Venezuelan Equine Encephalitis

Eastern, Western, and Venezuelan equine encephalitis are mosquito-borne viral infections that affect the brain and nervous system. ^[2][7] Inflammation within the brain can interfere with normal coordination and balance. ^[6][7] Vaccination has greatly reduced the frequency of these diseases in many areas. ^[7]

These diseases may cause fever, lethargy, abnormal behavior, weakness, seizures, or severe neurological dysfunction in addition to ataxia. Because these conditions can progress quickly and may be life-threatening, prevention through vaccination and mosquito control is an important part of risk reduction.

Head and Neck Injuries

Trauma affecting the brain, spinal cord, or neck can damage pathways responsible for coordination and movement. ^[2][6] Falls, collisions, and other injuries may cause temporary or permanent neurological deficits. ^[2][6] Because an ataxic horse may be unstable, safe horse handling is especially important while the horse is being assessed.

Injuries involving the head, neck, or spine can sometimes cause a sudden onset of ataxia. Horses with suspected trauma should be handled carefully and evaluated by a veterinarian before being moved, transported, or returned to exercise.

Equine Degenerative Myeloencephalopathy

Equine degenerative myeloencephalopathy is a progressive neurological disorder associated with degeneration of specific pathways within the spinal cord and brainstem. ^[2][8] The condition has been linked to vitamin E deficiency during early life and may have a genetic component. ^[2][8]

Signs are often symmetrical and may become more noticeable as the horse grows or is asked to perform more coordinated movements. Because EDM can resemble other causes of ataxia, diagnosis usually depends on the horse’s history, neurological examination, diet history, and exclusion of other conditions.

Equine Neuroaxonal Dystrophy

Equine neuroaxonal dystrophy is a neurodegenerative disorder that affects parts of the nervous system involved in coordination and movement. The condition is closely related to equine degenerative myeloencephalopathy and shares many pathological features. ^[2][8]

Clinical signs may include generalized incoordination, abnormal positioning of the limbs, and difficulty making smooth, controlled movements.

Like EDM, equine neuroaxonal dystrophy is often discussed in relation to vitamin E status and early-life development, but affected horses require veterinary evaluation to distinguish it from other neurological diseases.

Toxic Causes of Ataxia

Certain toxins, such as pyrrolizidine alkaloids and steroidal glycoalkaloids, can damage the nervous system and disrupt normal coordination. ^[2][6]

Exposure may occur through poisonous plants, contaminated feed, chemicals, or other environmental sources. ^[2][6] Examples in horses include toxin risks associated with poisonous plants and feed contaminants such as monensin.

Toxicity may also cause signs beyond ataxia, such as weakness, lethargy, digestive upset, liver disease, or sudden changes in behavior. If toxin exposure is suspected, owners should remove access to the suspected source and contact a veterinarian immediately.

Other Diseases of the Brain & Spinal Cord

Many other disorders can cause ataxia by affecting the brain or spinal cord. ^[2][6]

Examples include: ^[2][6]

• Tumors
• Abscesses
• Inflammatory conditions
• Congenital abnormalities
• Infectious diseases

The specific pattern of neurological signs often helps veterinarians narrow the list of possible causes.

Because many neurological conditions can look similar in the early stages, ataxia should not be attributed to a single cause without veterinary assessment. A complete history, neurological examination, diagnostic testing, and sometimes referral evaluation may be needed to determine the underlying problem.

Table 1. Common causes of ataxia in horses

Associated Signs

Ataxia is often accompanied by other neurological signs that can provide clues about the location and severity of the underlying problem. ^[1][2] The specific signs vary depending on which parts of the nervous system are affected. ^[3][5]

Signs that may occur alongside ataxia include: ^{[1][2][3][4][5][6]}

• Weakness or reduced ability to support body weight
• Stumbling, tripping, or dragging the toes
• Crossing the limbs or placing the feet abnormally
• Swaying or difficulty maintaining balance
• An exaggerated or irregular gait
• Muscle wasting or asymmetry
• Head tilt, abnormal eye movements, or other signs of vestibular disease
• Tremors
• Changes in behavior, awareness, or mentation when the brain is affected

Not every horse develops all of these signs, and the combination of abnormalities can vary considerably between different neurological diseases. ^[1][2] The presence of additional neurological signs often helps veterinarians determine which part of the nervous system is affected and narrow the list of possible causes. ^[3][5]

When to Call the Veterinarian

Ataxia should always be taken seriously because it can reflect disease or injury affecting the brain, spinal cord, peripheral nerves, or balance systems. Veterinary evaluation is important to confirm whether the horse is showing true neurological dysfunction and to identify the underlying cause.

Call your veterinarian if you notice:

• New or worsening incoordination, stumbling, swaying, or abnormal limb placement
• Weakness, difficulty rising, collapse, or inability to support body weight normally
• Head tilt, abnormal eye movements, tremors, behavior changes, or altered awareness
• Multiple horses showing fever, weakness, incoordination, or other neurological signs

Any neurological signs occurring after a fall, collision, suspected toxin exposure, or recent infectious disease exposure also warrant contacting your veterinarian.

Diagnosis of Ataxia

Diagnosing ataxia involves confirming whether abnormal movement reflects true neurological dysfunction, determining which part of the nervous system is affected, and identifying the underlying cause. ^[1][2]

Because many conditions can produce similar signs, diagnosis often depends on combining the horse’s history, neurological examination findings, and results from appropriate diagnostic tests. ^[1][2][6]

The evaluation usually begins with a detailed history and physical examination. Your veterinarian may ask when the signs first appeared, whether they are improving or worsening, and whether the horse has had a recent fall, collision, or illness. ^[1][2][6]

This information helps narrow the list of possible causes, such as infectious disease, spinal cord compression, trauma, toxic exposure, or degenerative neurological disorders. ^[2][6][7]

A neurological examination is used to assess gait, balance, posture, strength, limb placement, and cranial nerve function. ^[3][4] The veterinarian may observe the horse standing still, walking in straight lines, turning, backing, or navigating uneven surfaces, depending on what can be done safely. ^[1][3][4]

These tests help determine whether the horse is ataxic, weak, lame, or showing another type of movement abnormality. ^[1][3]

Veterinarians may also grade the severity of ataxia to help assess safety, monitor progression, and evaluate response to treatment. ^[1][3]

Other diagnostic tools may include: ^[2][6][7]

• Blood tests: May be used to evaluate overall health, look for evidence of infection or inflammation, assess organ function, and support testing for specific infectious or toxic causes
• Cerebrospinal fluid analysis: May help identify inflammation, infection, or evidence supporting diseases affecting the brain or spinal cord
• Imaging of the head or neck: Radiographs, ultrasound, or advanced imaging may be recommended to assess the skull, cervical vertebrae, spinal cord region, or suspected traumatic injuries
• Testing for specific diseases: Horses may be tested for conditions such as EPM and other infectious diseases based on clinical signs, exposure risk, and regional disease concerns

In some cases, diagnosis is straightforward, while in others, repeated examinations or additional testing may be needed to monitor progression and refine the suspected cause. ^[1][2]

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Treatment & Management of Ataxia

Treatment for ataxia depends on the underlying diagnosis, the severity of neurological signs, and whether the condition is likely to improve, progress, or require long-term management. ^[2][6] Because ataxia is a clinical sign rather than a specific disease, treatment is directed at the cause whenever possible. ^[1][2]

Some cases may require treatment aimed at reducing inflammation, controlling infection, supporting recovery after injury, or preventing further damage to the nervous system. ^[2][6][7]

Other causes, such as degenerative neurological disorders, may limit treatment to supportive care and management changes to improve safety and quality of life. ^[2][6][8]

Depending on the underlying diagnosis, treatment may include: ^[2][6][7][8]

• Medication: Conditions such as EPM may be treated with disease-specific medications, while viral diseases such as EHV-1 myeloencephalopathy or equine encephalitis often require supportive care and close veterinary monitoring. Depending on the diagnosis, veterinarians may recommend medications or supportive measures to help manage inflammation, pain, fever, weakness, or complications associated with neurological disease.
• Surgery: Some horses with cervical vertebral stenotic myelopathy, or Wobbler syndrome, may be candidates for surgical treatment.
• Management for trauma or toxin exposure: Horses with suspected injury or poisoning require prompt veterinary care, removal from the source of exposure when relevant, and treatment based on the affected body systems.
• Supportive or long-term management: Conditions such as equine degenerative myeloencephalopathy or neuroaxonal dystrophy may not be reversible, so treatment focuses on managing their safety, nutrition, and quality of life. Some cases of Wobbler syndrome may also be managed with exercise restriction and careful monitoring.

Management focuses on keeping affected horses safe. ^[1][6] Horses with significant ataxia have an increased risk of stumbling, falling, and injury, and they may also pose a safety risk to handlers and riders. ^[1][4]

Until the horse has been assessed by a veterinarian, avoid riding, driving, forced exercise, or unnecessary handling of an unstable horse.

Safety management may include: ^[1][6]

• Exercise restriction
• Stall rest
• Controlled turnout
• Improved footing
• Removal of obstacles
• Changes to feeding or watering arrangements

Horses with more severe ataxia may need to be kept in a secure area where they are less likely to fall, become trapped, or injure themselves. ^[1][4]

Veterinary guidance is especially important when deciding whether a horse can be safely transported, turned out, returned to work, or managed around other horses. ^[1][6] If an infectious neurological disease is suspected, biosecurity measures may also be needed to reduce the risk of disease spread within a barn or facility. ^[7]

Prognosis

The prognosis for horses affected by ataxia varies widely. Some horses improve with appropriate treatment, while others have persistent deficits or progressive neurological disease. ^[2][6]

Regular examinations may be needed to monitor changes in coordination, assess response to treatment, and adjust management recommendations over time. ^[1][2]

Prevention

Not all causes of ataxia can be prevented, but some risks can be reduced through appropriate health management. ^[2][6] Prevention strategies vary depending on the underlying disease. ^[2]

Measures that may help reduce the risk of neurological disease include: ^[2][6][7][8]

• Maintaining recommended vaccination programs for diseases such as EEE, WEE, VEE, and EHV-1
• Reducing exposure to mosquito-borne diseases through appropriate insect control measures
• Limiting exposure to toxins, poisonous plants, and contaminated feed
• Providing adequate vitamin E intake, particularly in young horses at risk of neurodegenerative disorders
• Following biosecurity practices during infectious disease outbreaks
• Reducing the risk of traumatic injuries through safe facility design and management
• Genetic testing before selecting breeding stock

Despite these measures, some causes of ataxia cannot be prevented completely. ^[2] Early recognition of abnormal movement and prompt veterinary evaluation can improve the chances of identifying and managing the underlying condition. ^[1][3]

Frequently Asked Questions

Here are some frequently asked questions about ataxia in horses:

Summary

Ataxia in horses is a neurological sign involving loss of normal coordination, balance, and accurate limb placement.

• Horses with ataxia may stumble, sway, drag their toes, cross their limbs, or move unsteadily.
• Normal coordination depends on the brain, spinal cord, nerves, cerebellum, and balance systems.
• Common causes include EPM, Wobbler syndrome, EHM, encephalitis, trauma, toxins, and degenerative disease.
• Ataxia can affect welfare, performance, rider safety, and the risk of falls or injury.
• Diagnosis requires a veterinary neurological exam, with treatment and prevention based on the underlying cause.