The spine is made up of individual vertebrae which articulate together to protect the spinal cord whilst allowing flexibility. The spine is anatomically divided into different regions, with the neck region being more correctly called the cervical spine. The first two neck (cervical) vertebrae are specialized so as to allow bending and flexing, as well of rotation of the head on the neck. These special bony blocks are known at the atlas and the axis. 

In certain (rare) conditions, the atlas and axis subluxate or dislocate, which puts pressure on the spinal cord. Not only is this very painful, in extreme cases it can cause complete paralysis of the cat from the neck down. 

Rest and neck braces at best represent a management strategy in the short term, but corrective surgery offers the best long term option. However, this is specialist surgery and referral to a veterinary orthopedic surgeon is likely to be required.

The full extent of the instability and any anatomical deficits must be fully assessed. However this needs to be done with extreme care since manipulating the head of an anesthetized cat could potentially cause spinal injury. Radiographs, CT or MRI scans can give valuable information that facilitates proper surgical planning. 

The cat is prepared for surgery with a general anesthetic, and the fur clipped over the dorsal region of the head and neck. Again, care is taken to support the head and neck, avoiding extreme flexion or extension in order to protect the spinal cord. 

The operation site is aseptically prepared and a long skin incision parallel to the spine. The soft tissues are dissected away until the atlas and axis are visualized. Depending on the nature of the deformity, the surgeon will drill tunnels through the wings or crest of these vertebrae. Sterile surgical wire is threaded through the tunnels and tightened so as to form a permanent support between the two bones. 

The skin is then sutured, the cat woken, and sent to recovery. 

Alternative techniques involve the use of stabilising orthopedic plates or pins. 

In the hands of a skilled surgeon this can be a highly successful operation. The procedure should permanently anchor the atlas and axis so they are not able to subluxate and pinch the spine. 

However, there are risks associated with surgery which range from poor positioning of the wires rendering the final outcome unsuccessful, through to iatrogenic damage to the spinal cord resulting in paralysis. 

Alternative techniques are now finding favor because of lower complication rates. These include stabilising the spine via a ventral approach, and using pins through the body of the vertebrae to fuse them together. 

It is essential that the cat is cage rested for at least six weeks after surgery. This allows inflammation to subside, reduces pain from movement, and gives the implants a chance to bed in. 

During the immediate postoperative period, it is vital to provide adequate pain relief. However, the absence of pain means the patient wants to be active, but this must be discouraged. 

The skin sutures are removed after 10 to 14 days. 

The cost of a presurgical CT scan to plan the surgery varies, but expect to pay between $800 and $1,500. The cost of the orthopedic surgery itself is likely to come in around $2,000 to $3,000

Atlantoaxial subluxation is a painful condition with potentially catastrophic consequences should paralysis occur. Neck braces and rest can help mild cases in the short term, as this gives swelling a chance to subside. However, in the long term, once the neck brace is removed there is nothing to prevent movement in the future. 

Surgery is the ideal option, as it provides a permanent long term solution. Each patient needs assessing on a case by case basis to decide on the severity of the instability, the risks, and outlook if nothing is done. In addition, thought needs to be given as to the best technique to achieve the aim of permanent stabilisation with minimal risk of paralysis. A specialist veterinary orthopedic surgeon is best placed to decide this. 

Cats with a developmental atlantoaxial subluxation should not be bred from, as they may pass the gene down to the next generation. 

Care should be taken to eliminate the risk of falls from high perches, such as a balcony or window ledge. To this end, instaling a cat-safe catio or using window guards is essential.