Michael Podell MSc, DVM

 

Diplomate ACVIM (Neurology)

 

WOBBLER'S DISEASE
Figure 1.  Pre- (A) and post- (B) operative CT myelogram images of cervical stenosis in a 1 year old Irish wolfhound.
                          A                                            B                 

A



Figure 2. Schematic of cervical vertebral instability due to spinal malarticulation, ligament hypertrophy and disk compression.



Myelogram demonstrating disk compression due to vertebral instability



Figure 3. Post-operative cervical distraction-fusion surgery with bone cement implant secured with cortical screws.
































    “Wobbler’s syndrome, also known as cervical vertebral instability (CVI) and cervical spondylomyelopathy (CSM), is a disease that affects large breed dogs, such as Great Danes, Mastiffs, Dobermans and Rottweiler breeds.  Both young and older dogs can be affected with different underlying causes. Younger dogs (less than 2 years of age) are most commonly affected by  stenosis of the cervical (neck) bones (vertebrae) causing a narrow opening around the spinal cord (Fig. 1).  The result is that the spinal cord is gradually compressed and atrophies over time.   Older dogs more commonly have a combination of a misalignment or malarticulation of the cervical bones that causes excessive movement (subluxation) resulting in secondary disk degeneration and surrounding ligament enlargement (Fig 2).  Over time, the spinal cord compression leads to atrophy and progressive clinical signs.

     Clinical signs are usually slowly progressive ataxia (incoordination) of the pelvic limbs with eventual involvement of the front limbs.  Acute worsening with pain, lifting a front leg, and sudden weakness or paralysis can occur.   A diagnosis is obtained with advanced spinal cord imaging to include either a MRI scan or combination of a myelogram and CT scan of the spinal cord.  With the latter test, the neck area is stretched to determine if the signs improve with simulation of distraction (the procedure done at surgery) to determine the type of surgery that can be beneficial.
    
Treatment revolves around pain relief, reduction of spinal cord swelling and ultimately, surgical correction of the problem.  Patients that present with pain only can often be treated with medical management consisting of pain medication and rest.  Dogs that exhibit weakness or ataxia are at high risk to continue to progress, as this disease is progressive.  As such, surgery is recommended for these cases. The goal of surgery is to decompress and/or stabilize the cervical spine.  Surgical strategies include removal of the disk (diskectomy) combined with distraction and stabilization techniques (to treat instability) (Fig 3) or dorsal laminectomy (Fig 1B) (to treat stenosis).  Post-operative rehabilitation is critical to their recovery for many patients.  Rehabilitation includes passive range of motion exercises and massage in the recumbent dog, hydrotherapy and controlled exercise.  Recovery of these dogs can range from several weeks to several months (6 – 12 weeks or more) due to the chronic nature of the disease.                 

     The prognosis for recovery after surgery is variable, depending often on the duration of signs, age of the patient, severity of the spinal cord compression, and degree of spinal cord atrophy present prior to surgery.  In general, approximately 80% of dogs affected for less than 1 year will have a good prognosis to improve.  The presence of multiple lesions and severe neurological deficits (non-ambulatory) worsens the prognosis.  Recurrence rate for additional problems developing at a new location in the neck area ranges between 10-20 percent over 2 years.  Early surgical fusion of suspicious sites adjacent to the main lesion may help to reduce this problem in the future.  New spinal fusion techniques, such as cortical bone allograft placement and titanium fixation devices, are being evaluated to enhance longer term improvement for our patients and pets.