Friday, January 17, 2014

Wobbler syndrome

Cervical vertebral instability is also known as Wobbler Syndrome, caudal cervical spondylomyelopathy, cervical vertebral malformation, cervical spondylolisthesis, cervical stenosis and cervical spondylopathy. Wobbler syndrome is a term loosely used to encompass compressive spinal cord lesions affecting the caudal cervical spine (the spinal cord at base of neck) in large- and giant-breed dogs. The cause is likely to be the result of genetic, nutritional and biochemical influences.

Look For

  • Neck pain – variable
  • Difficulty rising to a standing position
  • Worn toenails, scuffed paws
  • Incoordinated gait caused by decreased proprioception
  • Variable muscle atrophy, especially in forelimbs
  • Occasionally, the presence of Horner's Syndrome
  • Worsening of signs when the neck is flexed

    There are two distinct diseases described as Wobbler Syndrome.
  • The first disease is seen in young dogs (particularly Great Danes) arising from developmental abnormalities causing malformation and malarticulation of the spinal column – all cervical joints may be affected.
  • The second disease syndrome is seen in adult dogs (particularly Doberman pinschers) arising from type II disk herniation with accompanying vertebral ligamentous hypertrophy caused by vertebral instability.Dogs that have been diagnosed with Wobblers Syndrome should not be used for breeding or working.

  • The cause is likely to be multifactorial with genetic, nutritional and biochemical influences. The presence of a large, heavy head on a long neck may create abnormal forces that contribute to abnormal vertebral development.

    The spinal cord compression causes the clinical signs, particularly in the rear legs. Commonly, the first signs are simply slipping or scuffing the paws during exercise. Other signs are highly variable and depend on the degree of compression and the duration of the signs.

    Most cases have an acute onset. The course of the disease may be progressive (worsen over time) or static (be static and not change over time). Occasionally, dogs can be affected by an acute onset of quadraplegia (paralysis in all four limbs). Many times these dogs have shown no previous signs of neck disease and have no history of trauma.

    Two distinct diseases are described as Wobbler Syndrome. Both diseases have similar signs that relate to the animal's gait, which include weakness and incoordination in the pelvic (rear) limbs. It can cause paralysis of both thoracic and pelvic limbs.

    Developmental Abnormalities

    The first disease is seen in young dogs arising from developmental abnormalities causing malformation and malarticulation of the spinal column and is more common in young dogs from six-months to two years of age. In this disease all cervical joints may be affected.

    This disease is seen most frequently in Great Danes but other large- and giant-breed dogs may be affected. Nutritional studies in Great Danes have shown that ad libitum (free-choice) feeding of some diets in young dogs can increase the prevalence of the disorder. Chronic, excessive calcium intake in young dogs can result in hypercalcitonism, which disturbs skeletal remodeling and ossification and may contribute to abnormal vertebral development.

    Disk Herniation

    The second disease syndrome is seen in adult dogs arising from type II disk herniation with accompanying vertebral ligamentous hypertrophy caused by vertebral instability. This disease affects the disk spaces C5-6 and C6-7 but C3-4 and C4-5 may be affected. Multiple disk spaces may be affected. This disease entity is seen in mature dogs between three- and eleven-years-old with an average age of six years.

    In the disease seen in the older Doberman pinschers, it is usually caused by a disk degeneration secondary to vertebral instability.

    Other breeds that can be affected with Wobblers Disease include:

  • Mastiff
  • Rhodesian ridgeback
  • Irish wolfhound
  • Irish setter
  • Rottweiler
  • Labrador retriever
  • German shepherd
  • Golden retriever
  • Weimaraner
  • Great Pyrenees
  • Bernese Mountain Dog
  • Bouvier des Flandres
  • St. Bernard
  • Swiss Mountain Dog
  • Mixed breed dogs

    Dogs that have been diagnosed with Wobblers Syndrome should not be used for breeding or work.

    Other diseases that mimic Wobbler Syndrome include:
  • Trauma – car accidents or wounds from bullets or arrows
  • Diskospondylitis – in infection of the disk space and vertebrae
  • Cancer – primary or secondary (metastatic disease)
  • Inflammation or infection of the spinal cord
  • Juvenile orthopedic diseases – hypertrophic osteodystrophy, panosteitis, osteochondrosis dessicans

  • Diagnostic Tests

    Your veterinarian will perform a complete physical and neurological examination to assess the location and severity of the problem. Additional tests may include:

  • Baseline laboratory work consisting of a CBC, chemistry profile and urinalysis
  • Doberman pinschers and some of the older dogs should be tested for hypothyroidism. Hypothyroidism is not a cause of the disease but may impact treatment outcomes.
  • If surgery is contemplated, Doberman pinschers and other susceptible dogs should be tested for the bleeding disorder caused by Von Willebrand's disease.
  • Survey cervical radiographs. These radiographs are essential to make sure that some of the other diseases are not present including diskospondylitis, large bony tumors, fractures or other trauma.

    Radiographs will show a number of abnormalities associated with Wobblers disease including:
  • Tipping of the vertebrae into the spinal cord
  • Stenosis (narrowing) of the vertebral canal
  • Malformation of the vertebral bodies
  • Narrowing of the intervertebral disk space with arthritic changes

    Depending on your veterinarian's expertise and access to special imaging techniques, your pet may be referred to a specialist such as a neurologist-neurosurgeon for additional tests, such as:
  • Neuro-imaging by myelogram, CT-myelogram, or magnetic resonance imaging is required for diagnosing Wobblers disease in the dog. Neuroimaging allows determination of the exact location of the compression, the degree of compression and some prognostic information.
  • The choice of imaging techniques usually depends on your veterinarian's access and familiarity with some of the imaging modalities.
  • A CSF tap may be performed to assess for inflammatory-infectious diseases before performing a myelogram.

    Anesthesia is required for CSF tap and neuro-imaging. Anesthesia may make some dogs worse following the neuroimaging procedure. Most dogs that undergo myelograms and CT-myelograms become worse. This worsening is typically transient but can be permanent. Discuss the benefits and risks of the CSF tap and imaging with your veterinarian.

    Medical Treatment

    Dogs that are mildly or intermittently affected may be treated conservatively with restricted activity, nonsteroidal anti-inflammatory drugs, feeding from a height and the use of a chest harness rather than a collar.

    Dietary adjustment, if necessary, in young dogs as this appears to be associated with the disease seen in young, growing, giant breed dogs such as Great Danes. Dietary adjustment must be made slowly and with caution. Your veterinarian may recommend a nutritional consult to give your dog a strong chance for recovering from this disease.

    Medical treatment consisting of glucocorticosteroids may alleviate some signs of disease but effects may be temporary and may cause gastroenteritis and cystitis.

    A neck brace or cast may be recommended. Medical therapy may make your dog's condition degenerate. If you notice your dog's clinical signs worsening, notify your veterinarian immediately. It usually indicates failure of medical therapy. Your dog may require surgical intervention.

    Acupuncture or other alternative therapies may help your dog. Be cautious in allowing chiropractic adjustments to a moderately or severely affected dog.

    Surgical Treatment

    Moderately or severely affected patients usually require surgery to treat the spinal cord compression. There are veterinary neurosurgical specialists that do these kinds of procedures. Make sure you understand the risks of surgical treatment.

    In long standing compression, neurological deficits may be permanent. Surgical goal in these patients is to arrest the disease process. Understand from your veterinarian the goal in your pet before surgical intervention is performed. In general, the best surgical candidates are those that are still strongly ambulatory. Patients that cannot stand or walk have a very guarded prognosis. If your dog is quadraplegic or paralized, a long recovery is likely and some dogs will never be able to walk no matter how talented your neurosurgeon is or how dedicated you are.

    Surgical treatment is aimed at decompression (relieving the impingement of the spinal cord) and depending on the nature of the lesion, fusion or stabilization may be needed. Stabilization may require the insertion of bone cement or screws into the vertebrae. Some dogs may benefit from having a neck brace or cast placed post-operatively.

    Physical therapy and exercise restriction are essential for your pet's full recovery. Keep all appointments for reassessment. Let your veterinarian know immediately if anything changes in your dog's signs.

    Your veterinarian will need to reassess your pet's response to therapy through neurological examinations. Repeat radiographs of your dog's neck may be needed if surgical tharapy was performed or if your dog's condition deteriorates after treatment.

    Your pet may be placed in a neck brace or cast. Make sure you follow instructions for proper care. If the brace or cast gets soiled or wet, it will need to be replaced.

    Confinement for a set amount of time (usually 4-8 weeks after surgery) is strongly recommended. Limit jumping and leaping from elevated areas.                                                                           Physical therapy following surgery will maximize your pet's return to function. Physical therapy usually consists of standing exercises, passive range of movement, slow walks and sometimes hydrotherapy. Always work with your veterinarian in planning physical therapy. Frequent reassessment is necessary for adjusting and obtaining the best physical therapy plan for your pet. Feeding your pet from an elevated surface may improve the clinical signs. Prevent obesity in animals that are predisposed to Wobblers disease.
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