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Atlantoaxial (AA) Luxation

Black Toy Poodle in the park

Toy breeds including Yorkshire Terriers, Toy Poodles, and Chihuahuas can make wonderful companions. However, they are also the breeds most commonly affected by atlantoaxial luxation. Atlantoaxial luxation (or AA luxation) is a spinal disorder where there is excessive movement between the first two bones in the neck. This is often the result of an abnormally-formed AA joint, where the atlas (C1) and axis (C2) bones do not fit together properly.

What are the Symptoms?

Instability in the AA joint can cause pressure on the spinal cord of the neck, resulting in neck and neurologic symptoms. These can include:

  • Holding the head low
  • Weakness or wobbliness in all four legs
  • Inability to stand or move the legs
  • Difficulty breathing

Is your dog a toy breed suffering from possible neck pain? Are they having trouble walking? Let us know.

dr-wong-with-small-dog

What Causes Atlantoaxial Luxation?

The bones of the neck are usually held together with ligaments. In toy breeds, the bones and sometimes the ligaments are abnormally formed. Even gentle activities can result in damage to the ligaments, causing the bones to fall out of alignment (like a dislocated shoulder).

How Do We Diagnose AA Luxation in Dogs?

Our veterinary neurologists use different imaging tools to properly diagnose AA luxation. X-ray may show misalignment between the bones, but by itself, it is not always enough to diagnose AA luxation. An MRI is needed to see any spinal cord compression, bruising, or other problems. A CT scan is sometimes performed after the MRI if surgery is planned.

What is the Best Treatment for AA Luxation?

For the best chance of long-term success, we recommend surgery to stabilize the bones of the AA joint. In this procedure, we need to fuse the C1 bone to the C2 bone using bone cement and surgical screws. Surgery has a 90% success rate, while nonsurgical management involving crate rest and a body splint has a roughly 50% success rate. In the latter case, recurrence of joint instability is about 40%.

If you have any questions about your pet’s prognosis, give us a call today.

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