Neck Pain (Cervical Dysfunction)
Basic Information 
Epidemiology
Risk Factors
• Nutritional factors linked to osteochondrosis development include overfeeding (high protein and carbohydrates), calcium-phosphorous imbalance, copper or manganese deficiency, and zinc excess.
• Cervical vertebral instability or chronic microtrauma
• Abnormal biomechanical forces associated with the ill-fitting or improper use of draw reins or other restraint or training devices
• Exposure to environmental oxidants and vitamin E deficiency
Clinical Presentation
Disease Forms/Subtypes
• Congenital: Occipitoatlantoaxial malformation (OAAM) in Arabians
• Developmental: Osteochondrosis of articular processes, vertebral canal stenosis
• Degenerative: Osteoarthritis of cervical synovial articulations
• Traumatic: Cervical fractures, penetrating wounds
• Infectious (neurologic): Equine protozoal myelitis (EPM)
• Infectious (osseous): Discospondylitis, vertebral osteomyelitis
• Inflammatory: Intramuscular vaccine reactions
• Nutritional: High-protein and high-carbohydrate diets, vitamin E deficiency
• Neoplasia: Cervical vertebral myeloma
• Vascular: Thrombophlebitis of the external jugular vein
• Iatrogenic: Improper fit or use of training devices used for restraining head and neck position
History, Chief Complaint
• History of having the head or neck caught in a fence
• History of a fall or running into a solid obstacle or jump
• Abnormal conformation or head and neck carriage
• Neck held in a fixed or guarded position
• Inability to raise or lower the head and neck
• History of recent intramuscular injection
• Pronounced heat or soft tissue swelling
• Head shyness or resentful of palpation of the poll region
• History of pulling back in the cross-ties or flipping over
• Unwillingness to work on the bit
• Difficulty or resistance in turning in one direction
• History of recent respiratory infections or abortions on the farm
Physical Exam Findings
• Abnormal head and neck posture
• Pain elicited on palpation of the cervical musculature
• Localized heat or soft tissue swelling
• Local muscle atrophy or regional lack of cervical muscle development
• Cervical muscle hypertonicity, fasciculations, or fibrosis
• Resentment of poll flexion or extension
• Pain elicited on manipulation of the head or neck
• Audible or palpable crepitus with induced neck motion
• Lateral bending joint range of motion (ROM) asymmetry
• Loss of local skin sensation along the lateral neck
• Focal or patchy neck sweating (caused by focal sympathetic degeneration)
• Ataxia, spasticity, or weakness (pelvic limbs more affected than the thoracic limbs)
• Stumbling, toe dragging, circumduction of the pelvic limbs, or truncal sway
• Delayed response to proprioceptive challenges or abnormal limb positioning
