Atlantoaxial Instability / Subluxation

Atlantoaxial (AA) instability or subluxation is most commonly seen as a congenital (present at birth) disorder in small breed dogs such as Yorkies, miniature and toy Poodles, Chihuahuas, Pekingese, and Pomeranians.  Larger breeds can also be affected, and any dog or cat is at risk of a very similar acquired injury if they sustain trauma, such as being hit by a car.

In the congenital form of AA instability, the animal is born with abnormal bony or ligamentous connections between the first two vertebrae in the neck.  The instability present between these vertebrae can cause the vertebrae to shift and injure the spinal cord.  Clinical signs of such an injury include neck pain, weakness in all limbs, and potentially paralysis from the neck down and death.  Most dogs with AA instability will develop clinical signs within the first 2 years of life, often after a seemingly mild traumatic event.

AA instability is typically diagnosed by performing radiographs (x-rays) of the neck.  Treatment is via one of two methods:

  1. Medical management entails strict cage rest and placing a neck brace (from in front of the ears to the mid-chest) to prevent the vertebrae of the neck from moving and causing more damage to the spinal cord.  Pain medications and anti-inflammatories are typically also prescribed.
  2. Surgical management is recommended for those with severe signs and for those who have tried and failed medical management.  The aim of surgery is to stabilize the AA joint internally to prevent future spinal cord injury.  The success rate of this surgery is 80% or greater; however, there are many potential complications and a mortality rate of 5-10%.

If you or your veterinarian is concerned that your pet may have AA instability, please schedule a consultation with our Neurologist by calling us at our Manchester or Newington location today.