Medulla spinalis
The equine spinal cord is a cylindrical column of neural tissue extending from the brainstem through the vertebral canal to approximately the first sacral vertebra. It is organized into white matter tracts (ascending sensory and descending motor pathways) surrounding a butterfly-shaped core of gray matter containing neuronal cell bodies. The cervical intumescence (C6-T2) and lumbar intumescence (L4-S2) are enlarged regions providing innervation to the forelimbs and hindlimbs respectively. The cord is protected by three meningeal layers (dura mater, arachnoid, pia mater) and bathed in cerebrospinal fluid.
The spinal cord extends from the foramen magnum to approximately the first sacral segment. The cervical (C6-T2) and lumbar (L4-S2) intumescences are enlarged regions housing motor neurons for the limbs. Upper motor neuron (UMN) signs (spasticity, hypermetria) occur with lesions above the intumescence; lower motor neuron (LMN) signs (flaccidity, hyporeflexia, rapid atrophy) occur with intumescence lesions. Cervical radiography, myelography, CT, and standing MRI are diagnostic imaging options.
Diffuse neuraxonal dystrophy affecting the brainstem and spinal cord, associated with vitamin E deficiency in genetically predisposed horses. Neuroaxonal dystrophy (eNAD) is the milder early form.
Neuropathogenic strains of EHV-1 cause vasculitis in the CNS, leading to ischemic damage to the spinal cord and brain. The D752 mutation in the DNA polymerase gene is associated with neuropathogenicit
Fracture or luxation of vertebrae with secondary spinal cord compression. Most common at C1-C2 (atlas-axis), C3-C4, and the thoracolumbar junction.
Acquired neurodegenerative disease of lower motor neurons, strongly associated with chronic vitamin E deficiency (prolonged lack of pasture access). Histologically similar to human amyotrophic lateral
Wobbler syndrome, also known as cervical vertebral stenotic myelopathy, is a neurologic condition caused by compression of the spinal cord in the neck. It leads to progressive incoordination (ataxia),
Diffuse neuraxonal dystrophy affecting the brainstem and spinal cord, associated with vitamin E deficiency in genetically predisposed horses. Neuroaxonal dystrophy (eNAD) is the milder early form. Signs include: Symmetric ataxia and weakness in all four limbs (hindlimbs worse); onset before 2 years of age; abnormal base-wide stance; hypermetric gait; no cranial nerve deficits
Neuropathogenic strains of EHV-1 cause vasculitis in the CNS, leading to ischemic damage to the spinal cord and brain. The D752 mutation in the DNA polymerase gene is associated with neuropathogenicity. Signs include: Acute onset hindlimb ataxia and weakness following fever; urinary incontinence and bladder distension; perineal and tail hypalgesia; dog-sitting posture; may progress rapidly to recumbency; Fever followed 6-10 days later by acute hindlimb ataxia and weakness; urinary incontinence; perineal hypalgesia; may progress to recumbency; outbreaks common
Fracture or luxation of vertebrae with secondary spinal cord compression. Most common at C1-C2 (atlas-axis), C3-C4, and the thoracolumbar junction. Signs include: Acute onset of severe ataxia or paralysis caudal to the lesion; neck pain with cervical fractures; recumbency if cord transection is complete; may be asymmetric
Acquired neurodegenerative disease of lower motor neurons, strongly associated with chronic vitamin E deficiency (prolonged lack of pasture access). Histologically similar to human amyotrophic lateral sclerosis (ALS). Signs include: Generalized muscle wasting (especially epaxial and quadriceps); trembling; weight shifting; low head carriage; excessive recumbency; tail head elevation; characteristic lipofuscin deposits in retina
Wobbler syndrome, also known as cervical vertebral stenotic myelopathy, is a neurologic condition caused by compression of the spinal cord in the neck. It leads to progressive incoordination (ataxia), primarily in the hind limbs. There are two main forms: Type I (dynamic compression in young horses) and Type II (static compression in older horses due to osteoarthritis). ## What it is In Type I wobbler syndrome, developmental abnormalities of the cervical vertebrae cause narrowing of the vertebral canal and dynamic compression of the spinal cord during neck movement. It typically affects horses between 1 and 4 years of age, most commonly at C3 to C5. Type II wobbler involves static compression from osteoarthritic enlargement of the articular facets, usually affecting older horses at C5 to C7. Both forms result in damage to the spinal cord, leading to proprioceptive deficits and ataxia that is usually worse in the hind limbs. ## Signs and symptoms - Progressive hindlimb incoordination and ataxia - Wide-based stance and stumbling, especially when turning or going downhill - Toe dragging and difficulty backing - Neck stiffness or pain in some cases - In severe cases, weakness or falling - Symmetric or slightly asymmetric ataxia that is worse in the hind limbs than forelimbs - Positive cervical flexion test in many cases ## Causes and risk factors Type I wobbler is developmental and linked to rapid growth, genetic factors, and nutritional imbalances (especially copper deficiency or excess protein/calcium in young horses). Type II is associated with chronic wear and osteoarthritis of the cervical facet joints. Risk factors include large body size, rapid growth rates in young horses, and conformational issues that place abnormal stress on the neck. ## How it is diagnosed Diagnosis is based on clinical neurologic examination and confirmed with radiographs and myelography or MRI. Standing or recumbent radiographs can show vertebral canal narrowing or facet joint changes. Myelography or MRI provides the most accurate assessment of spinal cord compression. A neurologic grading system helps quantify the severity of ataxia. ## Treatment and management Treatment depends on the type, severity, and age of the horse. Conservative management includes stall rest, anti-inflammatory medication, and controlled exercise. For young horses with Type I, dietary management and restricted growth may help. Surgical options (ventral interbody fusion or dorsal laminectomy) are available for selected cases and can improve neurologic function in many horses. Prognosis varies widely depending on the severity and duration of compression before treatment. ## When to call the vet Contact your veterinarian promptly if your horse shows incoordination, stumbling, or difficulty backing or turning. Early diagnosis improves the chance of successful management or surgical intervention. ## Prevention For Type I wobbler in young horses, prevention focuses on balanced nutrition (avoiding excessive protein and calcium while ensuring adequate copper and other minerals) and avoiding overly rapid growth rates. Regular monitoring of at-risk young horses can help with early detection. ## Frequently asked questions **Can a horse with wobbler syndrome be ridden?** Many horses with mild to moderate signs can be ridden carefully after treatment, but those with severe ataxia are usually retired for safety reasons. **Is surgery always successful for wobbler syndrome?** Surgical success rates are good in appropriately selected cases, but results vary depending on the severity and chronicity of spinal cord damage. **Is wobbler syndrome hereditary?** There is a genetic component, especially in Type I. Breeding horses with wobbler syndrome or from lines with high incidence is generally discouraged. This information is for educational purposes only. Always consult with a licensed veterinarian for diagnosis and treatment of your horse. Signs include: Progressive hindlimb incoordination and ataxia; wide-based stance and stumbling, especially when turning or going downhill; toe dragging and difficulty backing; neck stiffness or pain in some cases; in severe cases, weakness or falling; symmetric or slightly asymmetric ataxia worse in hind limbs; positive cervical flexion test in many cases
The spinal cord extends from the foramen magnum to approximately the first sacral segment. The cervical (C6-T2) and lumbar (L4-S2) intumescences are enlarged regions housing motor neurons for the limbs. Upper motor neuron (UMN) signs (spasticity, hypermetria) occur with lesions above the intumescence; lower motor neuron (LMN) signs (flaccidity, hyporeflexia, rapid atrophy) occur with intumescence lesions. Cervical radiography, myelography, CT, and standing MRI are diagnostic imaging options.
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