Age Commonly Affected:
Less than two years old
Commonly Affected Breeds:
Toy Breed Dogs (Yorkshire Terriers, Chihuahuas, Miniature Poodles, Pomeranians, Japanese Chin, Pekingese)
Signs & Symptoms
- Gait abnormality
- Neck pain
- Paralysis (in severe cases)
- Difficulty breathing (in severe cases)
History of cervical pain, low head carriage, lack of muscle movement coordination (ataxia), loss of voluntary movement on all four legs.
Atlanto-axial instability/luxation is a congenital abnormality caused by a malformation between the first two vertebrae in the spinal cord. This connection, extremely unstable, predisposes the spine to luxation. When this happens, the spinal cord becomes severely compressed.
Physical Examination Findings
Neurological deficits suggesting a cervical spinal cord lesion, including weakness in all four limbs and normal or increased thoracic and pelvis limb reflexes; paralysis on all four limbs is rare.
Radiographs (x-rays) may indicate lack of normal bony structures important to the stability of the spine (dens). Dynamic instability when neck carefully flexed, dislocation (luxation) of the vertebrae from their normal location. MRI is also beneficial in diagnosis of Atlanto-axial luxations.
Generally, surgical stabilization of the spinal cord is recommended to prevent further dislocation. However, conservative medical management can occasionally yield positive results. This consists of splinting the neck with a padded bandage for several months to allow the body itself to stabilize the joint.