Atlantoaxial Instability in Cats
Key takeaways
Atlantoaxial instability (AAI) in cats is a rare condition affecting the first two vertebrae in the neck, known as the atlas and axis bones.
- These bones are responsible for head movement; instability in the joint between these two bones results in pain and damage to the spinal cord
- Symptoms of AAI include neck pain, stiffness, reduced range of motion, and in severe cases, paralysis
- AAI develops from malformation of the neck ligaments, or from traumatic injuries to the neck
- Diagnosis involves physical examination, X-rays, CT or MRI scans
- Treatment options involve conservative management such as, rest and pain relief, and surgical stabilization of the vertebrae
- Prognosis depends on the extent of the instability and spinal cord damage: severe cases involving paralysis are often irreversible and result in humane euthanasia, whereas mild cases respond well to treatment but sometimes recur
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A closer look: Atlantoaxial Instability in Cats
The spinal column is made up of individual bones called the vertebrae. There are five regions within the spinal column, the first being the cervical region which contains the atlas and axis bones.
Most cats present with neck pain and reluctance to move. In severe cases, compression of the spinal cord results in significant dysfunction or even paralysis. Cats with AAI benefit from prompt veterinary attention. Cats with signs of paralysis, such as being unable to walk on all four limbs, require emergency evaluation.
Risk factors
Atlantoaxial instability (AAI) is a rare condition in cats. Symptoms vary due to variance in the extent of instability and degree of spinal cord compression. Some cats with mild or no spinal cord compression show only symptoms of neck pain, with little or no weakness. Increasing instability and compression results in more severe symptoms and a poorer prognosis. The severest cases have symptoms such as complete paralysis of all four limbs and collapse.
Possible causes
AAI results from:
- Instability of the atlas and axis bone due to poorly developed ligaments. This abnormal development may be hereditary in some cat breeds.
- Injury such as a car accident or falling from a height, resulting in fracture of the axis
Main symptoms
Testing and diagnosis
Diagnosis of AAI includes:
- Physical examination
- X-rays
- CT scan
- MRI scan
Steps to Recovery
Conservative management can be successful in many cases, however surgical intervention is considered the definitive treatment.
Conservative management options include:
- Crate rest
- Neck brace
- Pain relief
- Anti-inflammatories
Frequent rechecks are needed to ensure symptoms are not worsening, particularly after the neck brace is removed. If conservative management fails and symptoms recur or do not improve, then surgical stabilization is recommended. In both conservative and surgically managed patients, rehabilitation can help improve neurologic function.
Prognosis varies depending on the extent of the spinal cord compression. Cats with mild instability normally respond well to conservative treatment and recover, however symptoms may recur. Cases with moderate compression of the spinal cord often improve with surgical stabilization of the bones, but may not recover full function. Cats with severe neurological deficits or paralysis sometimes require humane euthanasia.
Prevention
Individual cases of AAI are not preventable. Cats with non-traumatic AAI should not be bred.
Is Atlantoaxial Instability in Cats common?
AAI is a rare condition in cats.
Typical Treatment
- Crate rest
- Neck brace
- Pain relief
- Anti-inflammatories
- Surgical stabilization
