Vertebra cervicalis IV (C4)
C4 is a typical mid-cervical vertebra with a robust body and well-developed articular processes. It contributes to the characteristic S-curve of the equine neck. The transverse processes provide attachment for muscles such as the longus colli and scalenus. Together with the other cervical vertebrae it supports the head and neck, allowing flexion, extension, lateral bending, and rotation. The neck functions as a balancing rod during locomotion. Cervical pathology at this level can contribute to neck stiffness or to spinal-cord compression.
Origin: N/A (bone)
Insertion: N/A (bone)
Action: Support the head and neck; allow flexion, extension, lateral bending, and rotation; the neck acts as a balancing rod during locomotion
Cervical pathology causes neck stiffness and neurologic deficits. Radiography, ultrasound, and myelography are used for diagnosis. Dynamic versus static compression is an important distinction.
## Overview Facet joint arthritis at C4 affects the articular processes around the fourth cervical vertebra. Like other mid-to-caudal cervical joints, it can produce stiffness, resistance to bending,
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),
Resistance to lateral bending, neck stiffness, or progressive incoordination should be evaluated. Most mild neck stiffness improves with rest and controlled exercise.
## Overview Facet joint arthritis at C4 affects the articular processes around the fourth cervical vertebra. Like other mid-to-caudal cervical joints, it can produce stiffness, resistance to bending, and, when osteophytes are large, nerve-root irritation. Clinical signs must be correlated with imaging because radiographic osteoarthritis is common in asymptomatic horses. ## Causes Chronic repetitive loading and occasional trauma lead to cartilage degeneration and new bone formation. ## Diagnosis Neck mobility assessment, radiographs, ultrasound, and sometimes scintigraphy. Positive response to intra-articular analgesia confirms the joint as a pain source. ## Treatment Ultrasound-guided injection of corticosteroids, systemic anti-inflammatories, and rehabilitation exercises. ## Recovery and Prognosis Good for return to work in most cases after injection, although repeat treatment may be required. ## Prevention General management of training load and early treatment of neck discomfort. Signs include: mid-cervical stiffness; reduced range of motion; possible referred forelimb signs; osteophytes on imaging at C4
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
Cervical pathology causes neck stiffness and neurologic deficits. Radiography, ultrasound, and myelography are used for diagnosis. Dynamic versus static compression is an important distinction.
Resistance to lateral bending, neck stiffness, or progressive incoordination should be evaluated. Most mild neck stiffness improves with rest and controlled exercise.
See the Fourth Cervical Vertebra (C4) on our interactive 3D horse model. Open 3D Model