What Is Atlantoaxial Instability in Dogs?
The atlantoaxial (AA) joint in dogs is situated between the first and second vertebrae of the neck. The first vertebra, known as the atlas, and the second vertebra, called the axis, are connected by ligaments instead of a disc, enabling dogs to move their heads from side to side.
Atlantoaxial instability, or AA instability (AAI), is a rare condition in dogs where the alignment of the two bones is disrupted. This misalignment causes friction as the bones rub against the spinal cord and nerves, leading to severe neck pain and progressive neurological symptoms.
Symptoms
Dogs typically exhibit escalating neck pain, often yelping or crying upon touch. Additionally, they may display the following signs:
- Stiffness in the neck
- Carrying the head low, giving the appearance of bowing
- Inability to stand or walk
- Unusual gait or ataxia, resembling a drunken walk
- Difficulty or discomfort while eating or drinking
- In rare instances, apnea, resulting from diaphragm paralysis
- Mortality
It’s essential to recognize that these symptoms can stem from injuries, even minor ones, and may manifest randomly or persistently.
Causes
Atlantoaxial instability commonly arises from a congenital birth defect, affecting either the fitting of the cervical bones (C1 and C2), the connecting ligaments, or the bones themselves. Moreover, trauma, such as vehicular accidents, collisions with objects, or intense rough play, can induce the condition.
This instability primarily affects younger, smaller-breed dogs such as Chihuahuas, Pekingese, Pomeranians, Toy Poodles, and Yorkshire Terriers. However, it has also been observed in larger breeds like Rottweilers and Doberman Pinschers.
Diagnosis
Apart from conducting a physical examination, during which the dog often displays neck pain and reduced range of motion, veterinarians may suggest bloodwork and urinalysis screenings to rule out other potential causes and facilitate further evaluation. A comprehensive neurological examination will assess reflexes and cranial nerves, and X-rays are typically recommended.
Veterinary referral to a neurologist may be advised for advanced imaging procedures such as CT scans, MRIs, and possibly a CSF (cerebrospinal fluid) tap to assess the extent of spinal cord injury.
Treatment
For dogs experiencing minor discomfort or instability, conservative management involves strict crate rest for several weeks along with pain medications such as gabapentin, tramadol, opioids, NSAIDs, or steroids, along with a neck brace.
Surgery stands as the most effective option for dogs afflicted with this condition, despite its inherent risks due to its proximity to the brain and spinal cord. However, surgery offers the best chance of survival and long-term quality of life. The surgical objective is to minimize or eliminate pain and stabilize the joint, often achieved through screws and bone cement. Dogs with pre-existing medical conditions may not be suitable candidates for anesthesia.
Without surgical intervention, the prognosis for Atlantoaxial Instability is guarded, and symptoms may persist and worsen to the extent of compromising the dog’s quality of life.
Living and Management
For dogs managed solely with medications, it’s imperative to shield them from any form of trauma, including minor bumps and scratches, as recurrence of clinical signs can occur with devastating consequences. Even with diligent care, signs may resurface and progress, as previously mentioned.
Dogs that have undergone successful surgery can lead functional and normal lives. However, it’s advisable to avoid high-impact activities or rough play to prevent further trauma or surgical failure. Dogs presenting with neurologic signs or significant dysfunction at the time of surgery face a more guarded prognosis and may continue to experience neurologic issues post-surgery. The recovery period following surgery typically spans several weeks, with veterinary follow-up visits for repeat X-rays to monitor healing and function. After surgery, gradual reintroduction to exercise is recommended. Additionally, raised food and water bowls can help minimize neck movement.
