Wobbler syndrome in dogs: neck disease and weakness

Overview

The medical name is cervical spondylomyelopathy, or CSM, a disease of the neck vertebrae and spinal cord. It is also called cervical vertebral instability. The name Wobbler refers to the dog's swaying gait.

Narrowing disrupts messages between the brain and limbs. Hindleg weakness can therefore originate in the neck rather than the hindleg joints. The syndrome results from several different structural changes. Symptoms may develop gradually or start suddenly.

The disc-associated form is also abbreviated to DAWS. The form caused by bony changes is known by the abbreviation BACS. Both belong to the same syndrome, but the structure causing compression differs.

Causes

Disc-associated and bony forms

In the disc-associated form, a disc in the lower neck bulges against the spinal cord from below. Several discs may cause compression. Congenital narrowing of the spinal canal can add to this compression. Thickening of the ligamentum flavum between vertebrae may also worsen it.

In the bony form, the vertebral joint processes and parts of the arch enlarge, reducing space in the spinal canal. These changes usually affect the C4–C7 vertebrae. Narrowing in the lower neck can also compress nerve roots leaving the spinal cord. Nerve root compression may cause considerable pain.

Neck movement can change the degree of compression

Vertebral instability may contribute to the disease. In some dogs, disc compression decreases when the vertebrae are distracted during an investigation. Prolonged narrowing can lead to degeneration of the spinal cord itself. The precise underlying cause is not fully understood.

Discs act as shock absorbers between vertebrae. Disc rupture can suddenly increase spinal cord compression and cause paralysis.

Risk factors

Dobermanns and Great Danes are among the most commonly affected breeds. Other large and giant breeds can also develop the syndrome. It is rare in small dogs: only 5 dogs in a study of 104 were small.

Changes associated with the bony form in young dogs may develop as early as 4–12 months of age. The bony form can also become apparent later, from several months old up to 4 years. Symptoms of the disc-associated form usually start at 4–9 years. Around 7 years is considered a typical age of onset in Dobermanns.

In a veterinary patient database, the disease was recorded in 4.2% of Great Danes. The corresponding proportion in Dobermanns was 5.5%. These percentages concern dogs recorded in that database and do not establish disease risk in the wider dog population.

An inherited contribution is suspected, but the precise mechanism of inheritance is unclear. Canine DNA is still being studied to investigate genetic susceptibility.

A mean age at onset of 6 years has been reported for Dobermanns. In Great Danes, the mean has been 3 years.

Typical symptoms

Early unsteadiness may be visible only when walking slowly or on a slippery floor. Hindleg signs are often more obvious than front leg signs.

• The hindquarters sway, steps wander and your dog stumbles.

• Hindleg strides are long and unsteady, while front leg steps are short and choppy.

• Paws drag and the claws scrape against the ground.

• Claws wear unevenly or more heavily than usual.

• Your dog carries its head low or holds its neck stiffly.

• Lowering the head to a food bowl on the floor becomes difficult.

• Getting up becomes harder and the front legs may give way.

Muscle wasting may also appear around the shoulder blades. The front legs can become stiff and strongly extended. Shaking the head may make your dog yelp in pain.

Neck pain can range from mild to clearly noticeable. Symptoms often progress over months. Occasionally, a dog that seemed normal develops difficulty walking within just a few days.

Complications and consequences

Permanent nerve damage and loss of walking ability

A spinal cord compressed for a long time may be permanently damaged. Weakness and poor coordination may remain after treatment. Severe disease can cause loss of walking ability. Bladder or bowel control may be affected.

Sudden paralysis of all limbs has been described in about 5% of affected dogs. A dog left unable to get up may develop pressure sores. The disease can recur even after surgery if structural weakness in the spine continues.

Survival and treatment success are different outcomes

Average survival of about 4 years has been described in dogs followed with Wobbler syndrome. Survival did not differ between medically and surgically treated dogs in that comparison. Individual outlook depends on symptom severity, degree of compression and duration of symptoms.

The outlook is often best when compression comes from a single bulging disc that responds to traction. A mildly affected dog generally has a better chance of recovery than a severely affected dog.

Diagnosis at the vet

Examination establishes the source of unsteadiness

The vet performs general and neurological examinations to localise the signs to the neck portion of the spine. Gait and front and hindleg function are assessed separately. Examination also includes cranial nerve and tail function. Blood and urine tests can investigate other causes of similar symptoms.

Alternatives include injuries, congenital malformations and tumours. Spinal cord inflammation and bacterial infection of a vertebra and disc can also cause similar signs. Cerebrospinal fluid sampling may help investigate inflammatory diseases when needed.

The general examination also checks weight, body temperature, heart rate and breathing rate. Joint ranges of movement are assessed for other causes of mobility problems. Possible laboratory tests include a full blood count and blood biochemistry.

MRI and CT show different tissues

An ordinary X-ray does not confirm Wobbler syndrome. However, it may show abnormal vertebral structure or a bone tumour. MRI shows discs, soft tissues and the nature of spinal cord damage. CT shows bony structures in greater detail.

MRI and CT can complement each other when planning surgery. Dogs undergo imaging under general anaesthesia. In CT myelography, contrast is given around the spinal cord and its distribution assessed on images. Imaging can also investigate whether controlled neck traction reduces compression.

Conventional contrast X-ray imaging, or myelography, is used less often than previously. Mild, temporary worsening of neurological signs can occur after myelography.

Imaging establishes the number of compression sites and the severity of each change. Vertebrae may be imaged from different directions and sometimes with the head in different positions.

Treatment

Medical care and limiting strain

The vet chooses treatment according to symptom severity, compression sites and other diseases. Medical management may be chosen for a mildly affected dog or one unsuitable for surgery. It combines pain relief, reduction of inflammation and restricted exercise. An overweight dog may also need to lose weight.

Rest aims to reduce the effects of movement between unstable vertebrae and repeated spinal cord compression.

Medicine options include a corticosteroid or a non-steroidal anti-inflammatory drug. Active ingredients used may include prednisone or carprofen. Medicines relieve inflammation-related pressure but do not remove compressing bone or disc material.

Concurrent dilated cardiomyopathy may affect the choice of surgery.

Avoid free play, jumping and climbing during recovery. Short outings use a chest harness rather than a collar. During restricted exercise, an outing may mean a 5-minute lead walk, for example.

Surgery creates space or stabilises vertebrae

Surgery is considered for significant neurological deficits or an inadequate response to medical care. Direct decompression removes tissue beside the spinal cord that is pressing on it. Disc material can be removed through a ventral slot opening from the underside of the neck. Another option is dorsal laminectomy, removing part of the vertebral arch from above.

Vertebrae can be distracted and fixed in place for fusion. Indirect decompression suits cases where soft tissue that can be stretched is causing compression. An artificial disc is an option in some cases. No single surgical technique has been shown to be clearly best for every dog.

Outcomes and aftercare

About 50% of dogs improve with medical treatment. An unchanged condition has been described in about 25%. In an assessment of outcomes in 104 dogs, about 30% remained stable. In the same comparison, about 20% of medically treated dogs deteriorated.

Estimates of the proportion benefiting from medical treatment also range from 40–54%. About 80% of surgically treated dogs benefit. Some retain symptoms despite successful surgery.

Hospitalisation after surgery often lasts several days. Your dog may need help walking at home. Exercise is restricted for at least 2–3 months after surgery to allow tissues to heal. Rehabilitation may include supervised physiotherapy.

During early care at home after surgery, dogs are not allowed to use stairs or steps.

Prevention

Screening with ordinary X-rays is not suitable for controlling Wobbler syndrome in breeding in the same way as for hip dysplasia. Some breed clubs advise against breeding from an affected Dobermann even if it copes with its symptoms in daily life. A possible nutritional contribution has been suspected, but the precise mechanism of disease remains unclear.

In a dog with diagnosed disease, a chest harness reduces strain on the neck. Restricting jumping and climbing helps prevent deterioration during treatment. Soft bedding and position changes help prevent pressure sores in an immobile dog.

Important for dog owners

Note when unsteadiness began and whether it changes from day to day. Record a short walking video on a familiar surface if your dog can walk safely. Also record claw wear, difficulty getting up, eating and pain-related behaviour. Bring details of all current medicines to the appointment.

A dog unable to walk may also need help emptying its bladder and bowels. Severe weakness can develop gradually or suddenly.

Do not try the neck traction described in the imaging section at home. Before discharge, ask for practical instructions on lifting, support and toileting. Agree what exercise your individual dog is allowed and when follow-up will take place. Report new front leg signs and changes in pain, and compare daily function with the starting point.

Frequently asked questions

Why are the hindlegs unsteady if the disease is in the neck?

The spinal cord in the neck carries messages between the brain and limbs. Compression disrupts information controlling movement and limb function. Hindleg signs are often more pronounced than front leg signs, and the front legs may look normal early on.

Can a small dog develop Wobbler syndrome?

Yes, although it mainly affects large and giant dogs. For example, only 5 of 104 affected dogs in one study were small. Neck pain and unsteadiness in a small dog also need investigation, as other neck diseases can cause similar symptoms.

Does an ordinary X-ray show the disease?

An X-ray may reveal vertebral abnormalities but does not confirm Wobbler syndrome. MRI or CT investigates spinal cord compression in greater detail. MRI shows soft tissues, while CT shows vertebral bone structures, so their findings can complement each other when planning surgery.

Does every dog with Wobbler syndrome need surgery?

No: medical treatment and restricted exercise may be chosen for a mildly affected dog. Surgery is considered for more severe symptoms or when other treatment is insufficient. The specific technique is chosen according to the compression and structural changes seen on imaging.

Can my dog return to completely normal walking?

Some dogs improve well, but weakness and poor coordination may remain after treatment. Prolonged compression can permanently damage the spinal cord. The outlook depends partly on symptom severity and how long symptoms have been present.