Introduction
Frequently in large and giant breeds of dogs, especially Dobermans, a "wobbly gait" is noticed with progressive difficulties in the dog's movement. This phenomenon is a neurological disease in dogs that specifically affects the spine, specifically the cervical (neck) region. It is a painful and debilitating neurologic disease condition called Wobbler Syndrome, Wobblers or Wobblers disease. Wobbler syndrome, therefore, refers to a descriptive term for conditions in the spine of large and giant breeds of dogs, medically referred to correctly as cervical spondylomyelopathy. Other names for Wobbler syndrome include
Cervical vertebral instability (CVI),
Cervical vertebral malformation (CVM),
Cervical vertebral malformation-malarticulation (CVMM) and
Cervical spondylopathy.
Normal anatomy of a dog's neck (Cervical) bones
The neck is a continuation of the backbone (the vertebral column) and is made up of a series of small bones, the vertebrae. The vertebrae surround and protect the spinal cord, a large collection of nerves that transmit information between the body and the brain.
For the normal movement of the body and limbs, plus to feel sensations (including touch and pain), the spinal cord needs to be intact and undamaged. The individual vertebrae are separated by intervertebral disks, soft tissue structures that allow for normal movement between the vertebrae, and also act as shock absorbers.
What causes Wobbler Syndrome?
The Wobblers syndrome occurs in two forms:-
Disc-Associated Wobbler Syndrome (DAWS), and
Bony-Associated Cervical Spondylomyelopathy (BACS).
Disc-Associated Wobbler Syndrome (DAWS is associated with a “slipped disc” whereby an intervertebral disc herniation occurs and is commonly seen in large-breed dogs older than 3 years of age.
Bony-Associated Cervical Spondylomyelopathy (BACS) is associated with a bony malformation that leads to compression of the spinal cord causing gait issues and the dog experiences great pain if nerve roots are affected. This form of Wobblers is most common in giant-breed of dogs younger than 3 years of age, e.g. Dobermans and Great Danes.
There are seven vertebrae in the dog's neck region that surround and protect the spinal cord. In Wobblers syndrome (cervical vertebral instability), in the neck (cervical) region there is compression of the spinal cord and there is no longer normal movement of the neck. In this condition, there are abnormalities in the structure of the vertebrae, the ligaments that connect them, and/or the disks between them. The reasons for these abnormalities are not clear though inheritance through an autosomal recessive gene in the Great Dane, Doberman pinscher, and borzoi is a factor, including overfeeding of rapidly-growing large breeds of dogs with proteins and carbohydrates plus excessive nutritional calcium supplements to large breeds of dogs when they are growing. The results are instability between adjacent vertebrae, narrowing (stenosis) of the spinal canal, and pressure on the spinal cord that leads to weakness and incoordination in all 4 legs, a consequence of the compression of the spinal cord in the neck region - hence the name "wobbler", a characteristic sign shown by affected dogs, appearing to be unsteady on their feet.
Which breeds commonly develop Wobbler Syndrome?
Certain breeds of dogs are particularly at risk of developing this condition. Commonly affected breeds are Bassett hounds, Borzoi, Doberman Pinschers, German Shepherd, Great Danes, Irish Wolfhounds, Mastiffs, Rottweilers, and Weimaraner but any large or giant breed can develop the Wobbler syndrome.
Breeds of dogs that are commonly affected with the Wobblers syndrome.
What are the clinical signs of Wobblers Syndrome?
In both forms of Wobblers Syndrome, clinical signs occur slowly, or they can appear suddenly as it is a chronic, progressive disease (ie. it gets worse with time). The main clinical signs of this disease are weakness and incoordination (hindlimbs ataxia). There is no history of trauma and these signs begin insidiously and worsen slowly over several months with the dog seeming like he or she doesn't know where his or her feet are getting more obvious when s/he is rising from lying down or negotiating a turn or stairs. Over time, the dog develops a stiff, high-stepping, exaggerated gait that gradually worsens.
The signs occur equally on both sides with all four legs eventually affected, the hind legs being affected first, and more severely with a sudden change for the worse as a result of minor trauma. In Doberman pinschers, severe neck pain is sometimes experienced as a result of disk herniation and may develop rigid front legs.
In summary, the most common clinical signs noticed in a dog with Wobblers Syndrome are:
Strange wobbly gait
Neck pain, stiffness, holding head down and crying when shaking head
Weakness
Short-stride walking, spastic or very weak in the front limbs
Muscle loss near the shoulders
Worn or scuffed toenails from uneven walking
Increased extension of all four limbs
Difficulty getting up from a lying position
Partial or complete paralysis
Increased rigidity of forelimbs giving a short choppy gait.
Weakness and uncoordinated gait (known as ataxia), beginning in the hindlimbs.
Lameness in the front legs.
How is Wobblers Syndrome diagnosed?
Diagnosis of the Wobblers Syndrome can be done by one of the following:-
Clinical signs and performing a neurological examination.
Plain X-ray or myelopgraphy are taken to show structural abnormalities in the vertebrae and full general anesthetic is required to identify the precise location(s) where the spinal cord is compressed before appropriate treatment can be planned.
Other imaging techniques, such as magnetic resonance imaging (MRI) or computed tomography (CT) can also be used.
What is the treatment for the Wobblers syndrome?
Dogs with mild signs may improve with rest and medication, but surgery is often necessary. Most dogs (~80%) do well with surgery. Without treatment, the dog's condition gradually deteriorates. With therapy (either medical management or surgery) the prospect for recovery remains guarded for severe or chronic cases. Surgery is often indicated to improve the dogs quality of life and to prevent further deterioration. In old dogs or those which are considered a poor surgical risk, non-surgical measures may be most appropriate.
Surgery is difficult, time-consuming, and requires specialist expertise and the exercise has potential complications depending on a number of factors that can affect the outcome, e.g. the type of spinal cord compression (single site or at multiple sites), the time that clinical signs have been present, and the dog's weight and age.
The goals of medical management are to minimize neck movement (through confinement and use of a neck brace) and use anti-inflammatory medications to prevent further damage to the spinal cord. Medical management may be effective for weeks to years, although it does not address the underlying problem of spinal cord compression.
How is Wobbler Syndrome prevented?
The exact mechanism of inheritance is not known, however, dogs with cervical vertebral instability should not be bred. Breeding of parents or siblings that are considered potential carriers of the trait should be avoided. Besides, enquiring about this condition before acquiring a puppy or a dog is the best way of avoiding this condition in a large breeds of dogs. In case there is any family history of vertebral instability, refrain from providing mineral supplements to the diet, and feed several small meals daily (rather than ad libitum feeding).
References
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Other Sources Of Information
Typical gait pattern that may be observed in a dog with cervical disc disease. Fitzpatrick Referrals: www.youtube.com/watch?v=6_6cNZOYbL4
deLaHunta A (1983) In:Veterinary Neuroanatomy and Clinical Neurology. 2nd edn. Philadelphia: W B Saunders.
Bojrab M J (1993) Disease Mechanisms in Small Animal Surgery. 2nd edn. Philadelphia: Lea & Febiger. pp 979.