Atlantoaxial subluxation may occur alongside occipitoatlantoaxial malformation, a birth defect in which the occipital condyles – the “knobs” at the base of the skull that form a joint with the first vertebra – are absent or malformed. This condition can affect cats of any age, sex, or breed.

Spinal malformation in a cat’s neck – known by its technical name atlantoaxial subluxation – is a rare condition that affects the development of or results from injury to the spinal vertebrae in the neck. The disorder is characterized by trauma to or the absence of the dens, a structure in the spine which allows the head to rotate from side to side. The malformation will usually occur between the first and second vertebrae in the neck, and may compress the spinal cord and limit mobility.

Symptoms may appear gradually or suddenly depending on what caused the malformation. If you notice any of the following symptoms, seek immediate veterinary attention to prevent paralysis:

*This is a very severe symptom that accompanies general paralysis in which the diaphragm becomes paralyzed due to the malformation. Prognosis is poor, and may cause death before the animal has the chance to receive medical treatment. If your cat is unable to breathe, rush to the vet immediately.

The primary causes of spinal malformation of the neck in cats are birth defects or injury. Cats with spinal neck deformities will generally present symptoms when they are less than one year of age. There are no known breed, age, or sex predispositions for this disorder, apart from kittens with congenital spinal deformities. While other congenital spinal deformities are not causative of atlantoaxial subluxation, they may occur alongside it.

Be sure to inform your vet of the extent and duration of your cat’s symptoms as well as any traumatic injuries or birth defects that you know of. The vet may also ask for a complete medical history, so be prepared to provide it. The vet will make a tentative diagnosis based on presentation of symptoms. To reach a definitive diagnosis, the vet will first take an x-ray of the head without using anesthesia.  The vet may also choose to conduct a CT scan to check for additional abnormalities in the neck and spine.

Treatment methods may vary depending on the severity of the condition. Your vet will be able to recommend a treatment plan based on your cat’s individual needs. In cases which the condition is mild or not life-threatening, affected cats may be given a neck brace and placed on cage rest for a minimum of six weeks. Pain medication or steroids may also be prescribed.

Surgery may be required in severe cases that have resulted in any degree of neurological trauma in order to stabilize the joint and eliminate compression of the spinal cord. This will likely involve the use of pins, screws, or bone graft to secure the joint. In some cases, removal of the dens may be required, particularly if it is pressing on the spinal cord. Surgery is generally the preferred method of treatment, in both mild and severe cases, to prevent recurrence of spinal problems.

Prognosis and recovery time will depend on the severity of the condition. However, with early detection and treatment, the prognosis is more likely to be good even in severe cases. Always follow your vet’s post-treatment instructions carefully, and always administer medications for the full duration of the treatment period.

Your cat may be hospitalized for a short period following surgery to recover. After surgery, your vet may apply a neck brace for support and to promote healing. The vet may also recommend cage rest for six weeks. During cage rest, you will need to significantly limit your cat’s activity in order to prevent trauma recurrence. At present, no dietary changes in relation to the condition have been observed, although your vet may recommend them based on your cat’s needs.

The vet will schedule follow-up appointments every four to eight weeks, and will perform x-rays to monitor the condition. Since spinal deformities can recur, you will need to take preventative measures to protect your cat from trauma. It is imperative that you do this for your cat’s safety and wellbeing. If the condition recurs, there is a risk for spinal dislocation, which may result in permanent paralysis and death.

If the condition doesn’t seem to be improving, contact your vet immediately.