SPONDYLOLITHESIS

WOBBLERS SYNDROME

Description

Wobblers syndrome is caused by a narrowing or malformation of the spinal cervical (neck) vertebrae which causes pressure on the spinal cord by the lower cervical (neck) vertebrae due to either a malformation of the vertebra or a malocclusion (when the vertebrae do not come together properly). This causes anywhere from a mild, to a severe affect in the dogs gait.. Other conditions can mimic the symptoms. The only definitive diagnosis of Wobblers Syndrome or Spondololithesis, is a mylogram where dye is injected into the spinal column and then the neck is flexed and x-rayed.

Breeds affected: - Dobermans and Great Danes primarily - young Danes more commonly affected. Dobermans - young and old, can grow through the problem as youngsters, more commonly seen in middle aged to older Dobermans (3 to 9 years of age) Other breeds who have a similar if not identical syndrome described include the Boxer, Basset, Bull Mastiff, St. Bernard, Weimeraner, Labrador Retriever, German Shepherd, Rhodesian Ridgeback, Dalmatian, Samoyed, Old English Sheepdog, Irish Setter, and the Borzoi. Males are affected more often, in a ratio of 2:1

Cause

The cause of Wobblers Syndrome is unknown, although a link to fast growth and genetics is suspected. According to the Merck Veterinary Manual, "The cause is unknown, although rapid growth rates and nutrition, mechanical factors, and genetics may be implicated." Some breeders say that there has been a marked decrease in the incidence of not only Wobblers Syndrome, but other diseases that occur during the early, fast growth stages of Great Danes, when weight is kept down and growth rate has been slowed nutritionally.

Symptoms

Symptoms usually appear first in the rear legs as a mild uncoordination in gait (ataxia) and can escalate to involvement of the forelegs as well. The severely affected dog moves like a drunk and the uncoordination shows up most when the dog is walked and then moved sharply into a turn. An unsuspecting owner might simply conclude that his older puppy was just clumsy. Overly clumsy young Great Danes should be Wobbler suspects.

In Great Danes, Wobblers Syndrome most commonly appears from 10 months to a year and a half of age although it can manifest as old as 4 or 5 years, and as young as 5 weeks. In Doberman Pinschers it usually doesn't appear until the dog is 4 or 5 years old.

Diagnosis

A veterinarian will do a neurological work up on the dog and this often includes not only cervical spine x-rays, but a mylogram x-ray. A mylogram is not only dangerous to the dog, but is expensive. The owner should thoroughly investigate the advisability of this procedure, especially since if it is Wobblers Syndrome, surgery may not be the best option.

Treatment

Treatment of Wobblers Syndrome can include the use of corticosteroids, a neck brace and surgery. The surgery fuses the 2 unstable vertebrae which relieves the pressure on the spinal cord. Unfortunately this also puts further stress on adjoining vertebrae which can cause instability to recur in them. Many Wobblers can live a long and pain free life with little or no treatment. Others deteriorate quickly and euthanasia then becomes the only kind choice.

 


Wobbler's Syndrom

by Bruce R. Wittels, D.V.M.

The principal breed affected with Wobbler's Syndrome is the Great Dane. Cervical Spondylopathy or Canine Wobblers Syndrome as the lay person knows it, consists of any uncoordination or lameness caused by pressure on the spinal cord as it travels through the neck (at any age for any reason).

In Great Danes, a true wobbler is usually seen between the ages of 3-12 months of age. The outstanding symptom is a slowly developing, progressive, uncoordination and paralysis of the hind limbs. This paresis and/or uncoordination is caused by pressure on the spinal cord as it passes through the vertebrae of the neck, the last three being the most prominent sites. The animal may appear clumsy, "wobbling" or display swaying of the rear legs. On slick surfaces it may be difficult or impossible to walk. The dog may fall when attempting to turn and the toes of the hind feet may drag when walking. The dog usually has its legs spread out as far as possible trying to better balance itself. Initially front leg involvement is minimal or undetectable. As the disease progresses, a characteristic short choppy rolling stride is seen on what appears to be somewhat rigid forelimbs. As the compression of the spinal cord becomes more severe, the front legs can have the same signs as the rear legs. There is usually little or no neck pain but the dog may stand with the neck flexed which usually alleviates some of the spinal cord pinching. Many dogs will object to neck manipulation and may even collapse when the movement is forced.

On occasion, there can be an acute onset of signs. They are usually more severe than with the progressive type. Forelimb involvement is usually present. There is also a higher incidence of neck pain with the acute onset. This type of wobblers is seen most frequently in five to seven year old Doberman Pinchers and is rarely seen in young Danes. This must be differentiated from similar signs caused by cervical disc protrusion or a fractured vertebrae.

The pressure of the spinal cord is due to improper formation of the anatomical parts surrounding the spinal cord during growth. The pressure can be due to one or a combination of the following:

1. weak ligaments which hold the vertebral bodies in place - this allows irregular movement of the vertebral bodies as the neck is placed in various positions (subluxations) and causes a pinching of the spinal cord.

2.hyperplasia of the yellow ligaments - normally these are thin loose elastic sheets located between the arches of adjacent vertebrae. Just beneath them is the small epidermal space which is immediately above the spinal cord. With enlargement of these ligaments, the epidermal space is obliterated and the yellow ligaments push directly on the spinal cord.

3. malformation of the vertebrae - this can happen in various ways i.e.:

    a. Vertibral or spinal canal that is too small for the diameter of the spinal cord

    b. Assymetric cartilage defects which cause vertebral subluxations

    c. Osteochondrosis of the articular facets which also lead to subluxations

    d. Stenosis of the cranial orifices of vertebral foramina which causes a pinching of the nervous system
 

DIAGNOSIS
This is based on the breed, age, history and results of both a physical and neurological examination. Diagnosis is confirmed by radiographic examination. A minimum of three views should be taken: a side view with the neck in normal position, a side view with the neck in a flexed position (head pointed towards the feet), and a side view with the head in a skyward position. A subluxation of one or more vertebrae may be the only causative agent and is often only seen when the neck is in and extended or flexed position. At times, a view of the neck from top to bottom must be
taken. A mylogram might be needed to properly determine the exact compression sites. Other disease entities which can cause similar symptoms that must be differentiated from are: disc protrusions, infectious, neoplastic, vascular, or traumatic disorders of the spinal cord. Other bone disorders common to the giant breeds can cause gait abnormalities but are usually presented with a lot of pain and do not show any nervous system involvement.
 

CAUSES
The exact reasons why the aforementioned vertebral abnormalities occur are unknown. There is probably a genetic factor that comes into play. This is determined by a high incidence of Canine Wobblers seen in certain families of Danes. It is difficult to separate the genetic from the environmental factor (nutrition, management and activity) as most of these families are kept in the same environments because many breeders keep the pups for three to four months thus keeping the family under a similar environment. Deformity and displacement of the cervical vertebrae secondary to a long neck, large head and rapid growth has been proposed. 

In normal growth, expansion of the spinal canal must be perfectly synchronized with growth of the spinal cord.
Expansion is achieved by resorption of bone inside the vertebral canal. With hypercalcitonism, the retarded rate of bone resorption prevents proper expansion of the canal - therefore the diameter of the spinal canal is decreased and has an irregular contour. The spinal cord grows independently of the surrounding bone and is thus pinched by the nonresorbed bone therefore causing Cervical Spondylopathy.

Nerves leave the spinal cord, to go to other parts of the body, through spaces formed by notches is the vertebrae called foramina. A narrowness in these spaces will cause a pinching of the nerves leaving the spinal cord which in turn causes inflammation and swelling of the spinal cord itself thus causing wobblers syndrome. Hypercalcitonism causes narrowness in the vertebral canal can also yield a stenosis of the cranial orifices of the vertebral foramina due to its effect of slowing bone resorption. Hyper or over nutrition can also give the same results as an increased growth rate without proper mineralization and body controls can cause enlarged or asymmetric bone formation of the vertebrae in the neck as well as in any other bone in the body. This could easily result in pinching of the nerves as an overabundance of bone can yield improper notch formation.

Although the vertebrae may not be as flexible as other joints in the body - they do move and have joint surfaces as do other bones. The joint surfaces called "articular facets" are lined with a cartilage the same as those of other joints. Improper formation of these surfaces can cause the vertebrae to move improperly and cause luxation or subluxation which can cause pinching of the spinal cord. A mechanism that can cause such a situation is Osteocondritis Dessecans (OCD). For now, let's describe OCD as a disturbance of endochondral ossification (one type of bone formation) which leaves the joint cartilage thicker than normal. It is therefore further away from the blood supply leaving it more susceptible to injury and cell death which will cause poor rotation of the joint and hence subluxation. This can happen at all or only one of the facets in the cervical spine. Again the last three vertebrae are most commonly affected. Osteochondrosis will be more thoroughly discussed in the next issue of the Reporter. The main cause of OCD is overnutrition or ad-lib feeding. Hedhammer et all (1974) studied the relation between overnutrition and skeletal disease in growing Great Danes. In general - dogs fed ad libitum had smaller than cervical vertebral foramina (notches) with subsequent spinal cord compression as well as asymmetric vertebral articular facets. There was also OCD in the facets displayed as defects in the cartilage covering the facets. They concluded that "excessive intake of food rich in protein, energy, calcium and phosphorous accelerates growth and can induce various skeletal changes including changes in the cervical vertebrae that result in the wobbler syndrome."
 

TREATMENT
The treatment of cervical spondylopathy depends on the severity of the neurological involvement and the longevity of the disease process. Treatment is directed at stopping further cord trauma and at decreasing the current neurological deficits.

The acute form of canine wobbler syndrome is truly a medical emergency. The dog is very often quadriplegic and immediate veterinary attention must be sought in order for the spinal cord to be saved. Generally the veterinarian will treat the animal with diuretics (i.e. mannitol) and high dose steroids to decrease the swelling and inflammation in the cord as well as ascorbic acid to protect the myelin sheath that surrounds the nerves. This treatment may last as long as 2 to 3 days. Depending on the degree of improvement, decompressive surgery is usually required to prevent further trauma to the cord. If via rigorous medical treatment, the animal regains full neurological function, surgery may be delayed from one to three weeks with the animal probably kept in a neck brace. If, however, little or no improvement is rendered via medical care - surgery must be done within a few days in order to preserve the integrity of the spinal cord. The more time that passes with the spinal cord compressed and therefore without nutrients and oxygen, the higher the likelihood of some degree of permanent paralysis. The two most used surgical techniques are Dorsal Laminectomy (where the top of the spinal canal is removed thus allowing the spinal cord to rise out of the confining environment) and Ventral Decompression which removes ulcerated disc material as well as certain ligaments under the spinal cord and some of the vertebral body that may be compressing the cord.
Choice of surgical technique is made by the orthopedic surgeon or by someone that has had much experience with spinal surgery as well as the special instrumentation needed for this complicated procedure. Even with the correct facilities and techniques there are always possibilities of post operative complications.

Dogs with slowly progressive signs of Wobblers Syndrome often respond well to a combination of cage rest and corticosteroid therapy. I usually apply a neck brace as well to provide some stabilization of the neck and at the same time some traction as well. This is only if the syndrome is caught in the early stages. Remember that the above will only alleviate the effects of compression of the cord and does not and will not correct the vertebral and ligamentous changes. The IMMEDIATE thing to do is to reduce the protein level of the diet. A protein level not to exceed 22-24% should be fed. Any and all mineral supplements should be discontinued. All food and water must be elevated to further reduce neck tension. Ball playing or any action where the head is dipped down to snatch up an object is to be eliminated. A very concerted effort to restrain this dog from exercise is to be instituted as this can easily yield an increase in the likelihood of vertebral subluxation or further damage to the spinal cord. It is a known fact that
signs of joint instabilities are less severe in animals kept in a sedentary environment than those allowed unrestricted exercise. Hopefully if this is discovered early and the diet is changed while the bones are still forming and little recurrence of cord trauma occurs, the remaining formation of bone will be normal and the condition can stabilize itself to the point that surgery will not be needed. Surgery for the slowly progressive form of cervical
spondylopathy may not be as rewarding as with the acute form, if it is discovered late since the damage to the spinal cord may be permanent. It may however, prevent further damage to the cord.

Don't use Iams puppy food or A.N.F. 30 for instance. The extra calcium and protein in these foods could easily cause signs of the above. I would feed a multiple vitamin and absolutely no additives. Perhaps a little canned food to   increase the palatability.  Each litter must be treated individually. Don't equivocate your litter to your friend's. Don't ignore the possibility that your dogs might be more efficient in digesting foods and utilizing a higher percentage of available nutrients than someone elses. This could give the same effect of overfeeding without the addition of any supplements. Periodic radiographs may be advantageous to early detection of wobbler development. Again it is very important to put as little stress on the necks of these pups.

 

Sparrows Point , MD             (443) 800-5709           Tanya@GreatestDanes.com