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  • Writer's pictureStittsville Kanata Veterinary Hospital

Atlanto-Axial Instability in Dogs


As pet owners, ensuring the health and well-being of our furry companions is a top priority. Yet, there are medical conditions that can catch us off guard, such as Atlantoaxial Subluxation (AAS). This condition involves the misalignment or abnormal movement of the first two cervical vertebrae, known as the atlas (C1) and the axis (C2). These vertebrae are essential for supporting the head and facilitating neck movement. In this blog post, we will delve into the details of AAS, including its causes, symptoms, diagnosis, and treatment options.

Types of Atlantoaxial Subluxation:

There are two main types of AAS:

1. Congenital AAS:

- Congenital AAS is present at birth and is often seen in toy and small breed dogs.

- It is typically caused by malformation of the atlantoaxial joint.

2. Acquired AAS:

- Acquired AAS develops later in a dog's life and is usually a result of injury, trauma, or degeneration.

- Inflammatory conditions and degenerative changes in older pets can also contribute to its development.

Risk Factors:

Certain factors increase the risk of AAS in pets, including:

- Breed: Toy and small breed dogs, such as Chihuahuas, Yorkshire Terriers, and Miniature Poodles, are more susceptible.

- Genetics: Some individuals may be predisposed due to genetic factors.

- Anatomical Abnormalities: Pets with anatomical abnormalities, like a shallow cranial fossa, may be more prone to AAS.


The symptoms of AAS can vary depending on the stage of the condition:

Early Stages:

- Neck pain

- Reluctance to move

- Head tilting

- Changes in gait

Later Stages:

- Weakness

- Hind limb incoordination

- Paralysis

- Loss of bladder/bowel control


Diagnosing AAS involves a combination of clinical signs, physical examination, and diagnostic imaging. X-rays and advanced imaging like MRI or CT scans may be necessary for a definitive diagnosis. A referral to a radiologist or specialist may also be recommended.

Treatment Options:

Treatment options for AAS depend on the severity of the condition:

1. Conservative Management:

- Rest and limited activity.

- Anti-inflammatory medications.

- Pain relievers (NSAIDs) and muscle relaxants.

- Corticosteroids may be used to reduce inflammation in severe cases.

2. Surgical Intervention:

- In severe cases, surgery may be necessary to stabilize the joint and relieve spinal cord compression.

- Surgical complications can include infection and hardware failure.


The prognosis for AAS varies and is influenced by the severity of the condition. Early diagnosis and appropriate treatment offer better chances of recovery. Regular check-ups, neurological exams, and imaging are essential to monitor progress. Recurrence is possible, especially if underlying anatomical issues aren't fully addressed.

Prevention and Management:

To prevent AAS or manage it effectively:

- Avoid excessive neck movement and high-impact activities, especially in predisposed breeds.

- Strict cage confinement may be necessary after surgery to promote proper joint fusion and spinal cord recovery.

- Maintain a healthy weight to reduce strain on the spine.

- Provide elevated bowl feedings for added comfort.

It's important to note that AAS is not directly transmissible to humans or other animals.


Atlantoaxial subluxation is a challenging condition that can significantly impact your pet's quality of life. This blog post has provided an overview of its causes, symptoms, diagnosis, and treatment options. Remember that this information is generalized, and consulting your veterinarian for personalized advice and care for your pet is essential. By staying informed and proactive, you can help your furry friend lead a healthier and happier life.

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