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

This is the first in a series of articles that will discuss specific disease entities of bone caused, in part,
by improper or over nutrition. Some of the
information to be presented in this and future articles will have been discussed previously but will be
put into specific consideration to the disease
entity covered. It is my desire to provide an understanding of the total picture of proper nutrition and
a well balanced and strong skeleton upon which
these modern day giants are to support their massive bodies. If the foundation of any structure is
weak, then the weight which is born by it will cause
this foundation to break and fall.

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. (Weight et al 1973).

A vertebral canal that is too small for the diameter of the spinal cord could easily be caused by
nutritional hypercalcitonism. As discussed in my
second article, Nutrition of the Newly Born and Growing Individuals (GDR Jan/Feb '85). Calcitonin
is released from the thyroid gland when the
animal is fed a diet high in calcium. Its function is to retard bone re-absorption and thus decrease
blood calcium levels. Remember, calcium is kept
within strict limits in the blood stream. 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.

What can we do to prevent canine wobblers syndrome? My own observations and present studies
indicate a probable genetic factor that may
predispose certain lines or individuals to producing wobbler offspring. You as breeders must strongly
consider the use of these lines or individuals for
breeding purposes. You must answer to your own conscience and morals. The goal of breeders and
the purpose of breeding is to strive to ever better
the breed and those of you in breeding solely for the monetary gain must seriously reconsider this
motive!!!

One thing that we all must do is to refrain from that archaic urge to supplement the excellent
commercial foods available as the main cause of
growing bone disparities in the giant breeds is hypernutrition.. For those of you who have found that
one or two pups out of every litter or every other
litter have shown signs or have developed into wobblers, I recommend that you do your very best to
eliminate the environmental elements that might
encourage or enhance the pups' chances of developing into a wobbler. This would entail feeding the
entire litter the adult form of the high quality food
(22%-24% protein) starting at weaning time. 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 - directions to be followed as previously
described.
 

SUMMARY
There is no cut and dry answer or definition as to why or where this disease entity originates - this is
a fairly new area of veterinary science. We are
finding strong evidence suggestive to a genetic entity in this syndrome and have found definite proof
that nutrition plays a major role in the
development of wobblers and other bone disorders in the giant breeds. Again this is due to our
wanting only the best for our dogs and knowing that
the giant breeds need more nutrition than average dogs. Where we tend to go wrong is in the belief
that if a little more is good, than a lot more must be better. Take an honest look at your own feeding
program and look for areas where you might be able to improve the lives of your Danes.
  ------------------------------------------------------------------------------------------------
 

Wobbler Syndrome - in large breeds of dogs. (Caudal Cervical Vertebral Malformation and Malarticulation) (Caudal Cervical Spondylopathy and Myelopathy)

(Note #1)

This syndrome has also been called the "wobbler" syndrome, cervical vertebral instability, and
cervical spondylolisthesis. The
term "Wobbler" describes a nonspecific clinical picture, and the terms instability and
spondylolisthesis do not accurately
reflect the complexity of the syndrome nor the fact that instability is often not demonstrable. The
name cervical spondylopathy
more accurately reflects the complexity of the syndrome and therefore has become widely accepted.

The outstanding clinical feature is a slowly progressive upper motor neuron paraparesis and
incoordination. Cervical pain may
or may not be present. The neurologic deficit in the thoracic limbs is usually minimal and
occassionally nondetectable. The
reason the pelvic limbs seem more affected than the thoracic limbs is unknown, but deLahunta
(1977) suggests that the more
superficial position of the pelvic limb spinocerebellar tracts in the spinal cord at the site of the
compression may be the reason.
He also suggests that the further distance of the pelvic limbs from the center of gravity of the animal
may be important.

Although the spinal cord compression is usually in the caudal cervical area (area of lower motor
neuron supply to the forelegs),
upper motor neuron signs predominate in the forelegs. This finding reflects the fact that chronic spinal
cord compression
affects the white matter more severely than the gray matter. In some cases there is a lower motor
neuron involvement, usually
expressed as bilateral atrophy of the scapular muscles. The foreleg gait observed in many cases is
quite characteristic. The
forelegs appear somewhat rigid and the stride is short , choppy , and rolling. With greater degrees of
compression the thoracic
limb gait resembles the pelvic limb gait, that is, paretic and incoordinated. Occasionally the onset of
signs is acute, and the dog
is quadriplegic when presented to the clinician.

(Note #2)

Diagnosis...Breed, age and clinical signs suggest the diagnosis of cervical spondylopathy, which is
confirmed radiographically.
Changes seen on noncontrast radiographs may consist of (1) change in shape of the vertebral body
with apparent loss of the
cranioventral corner of the vertebral body. (2) abnormal width and shape of the disc space cranial to
the vetebral body defect.
(3) calcification of the affected disc, (4) reactive osteophyte formation and end-plate sclerosis
resulting from the instability of
affected disc, (5) malformation of the articular processes. Myelography is required to identiy the
nature and precise location of
extra-dural soft-tissue masses: disc hernation, thickening of the ligamentum flavum and joint capsule,
or thickening of the
dorsal longitudinal ligament. The use of a hyperextended lateral projection is of great value in
demonstrating the maximum
degree of cord compression.
 

Vertebral instability, either alone or in combination with vertebral malformation and/or soft tissue
stenosis has been suggested
as an initiating cause of spinal cord compression and associated neurologic abnormalities (VanGundy
1988 - Dobes).

Etiology (causative factors) - still obscure and include - genetics, rapid growth, nutrition. The high
incidence in certain breeds
suggests heredity is a contributing factor.

Structural Aspects - combined bone and soft tissue lesions (spinal cord compression) at C6-C7 and
C5-C6 are most commonly
seen, however C4-C5, and C3-C4 can be affected.

Malarticulation - allowing ventral displacement. This can be stable or unstable - the unstable cases
are often only visible on
flexed lateral views (Spondylolisthesis).

Malformation - changes can be secondary to malarticulation; the cranial edge of the vertebral
foramen may be stenotic with or
without deformities of the vertebral body. Arthritic changes, interbvertebral disc degeneration and
collapse, disc protrusion etc.
can occur in various combinations in older dogs. Most dogs have a combination of both
malarticulation and malformation.
 

Destruction of Neurons - in severe cases, neurons are destroyed at the site of injury, usually at C6
and C7 spinal cord segments.
Milder cases myelin may be lost at the site of injury, causing some loss of function that can be
repaired over time if the lesion is
stabilised.

Clinical Signs - vary widely. Seen as early as 2-4 months of age and as late as 8-9 years of age.

Neurologic dysfunction (signs visible) are due to the spinal cord compression exhibited in that dog.
Most commonly seen in the
younger dogs is hindquarter incoordination, wide based exaggerated movement and
proprio-receptive deficits (stumbling,
scrapping of toes). Frequent turning will often cause the dog to fall over in the hindquarters. Front
legs are usually less affected
than the hind-limbs, but affected dogs may have a restricted action, the limbs appearing rigid.

Rate of progression is variable according to the severity of spinal cord compression and the extent of
instability and damage.

Young Dogs - especially Great Danes (less than 2 years of age), frequently have dorsal spinal cord
compression due to
elongation of the cranial aspect of the dorsal arch of the affected vertebrae. Dobes, Danes may be 6
months or younger when
initial signs are noticed. Bull Mastiffs are generally less than 1 year of age. Affected Bassets are male,
generally less than 6
months of age and have a malformation of C3.

These dogs frequently have severe ventral spinal cord compression secondary to collapse of
theintervertebral disc and
proliferation of fibrous tissue around the unstable area.

Older dogs often exhibit pain on movement of the neck, particularly during flexion. Signs can be as
mild as neck pain to
tetraplegia (paralysis of all 4 limbs).

Diagnosis - When studying this disorder it must be determined that a neurological disorder exists and
not one of several
skeletal diseases that occur in young dogs including OCD, HD, HOD. Most of these disorders are
asymetrical, the gait appears
stiff and pain can be palpated in affected joints or limbs. Neurological cases with cervical lesions
have poor control over the
position of the limbs, hence the wide based stance, stumbling and proprio-receptive deficits (righting
relaxes of the feet).

.Disorders such as congestive cardiomyopathy or hypothyroidism are frequently diagnosed in the
Great Dane and the
Dobermann. TSH testing is recommended in any Dobermann Pinscher with clinical signs consistent
with cervical
spondylonyelopathy. Supplementation of hypothyroid dogs with T4 products is recommended, and
in some dogs may result in
dramatic clinical improvement. (Ettinger 1989) Hypothyroid neuromuscular dysfunction symptoms
include - weakness,
stiffness, reluctance to move knuckling or dragging of the feet with excessive wear of the dorsal
surface of the toenails and
muscle wasting

OCD of the cervical vertebral articular surfaces of young Great Danes may be a causative factor of
cervical vertebral
instability in this breed. Lesions seen were similar to those seen in Cervical Osteochondrosis in swine
(Olssen 1980).

Plain radiographs are useful for a rough diagnosis if there is vertebral malformation, however a
myelogram is necessary for
positive confirmation of the areas of spinal cord affected by compression. Apparent "tipping of
vertebrae", or coning of the
vertebral canal can be enormously misleading in demonstrating the involved vertebral interspaces.
Without myelograms,
accurate and complete diagnosis cannot be made. If surgery is needed, myelegrams are essential in
the selection of the most
appropriate surgical techniques that will stabilise the neck and allow the surgeon to assess the long
term prospects of the
affected dog.
 

  Treatment - depends on several factors - severity of the symptoms, age,
suddeness of onset, long  term prospects.

Conservative - rest and cortiocosteriods are most effective in many cases. Surgery is advocated
where response to
corticosteroids is poor and clinical signs and/or the radiographic signs are severe. Younger dogs are
often treated this way
initially, however if signs persist, surgical intervention is necessary if long term improvement is to be
gained. Occasionally a
young dog may "grow out" of their problem by enlarging their verterbal canal sufficiently to
accommodate the spinal cord.
Older dogs, where the pain is readily controlled with rest and medication, can often be managed on
long term cortico-steroid
therap.

Surgical - rule of thumb on this type of treatment is based on the age of the dog i.e.. if 6-8 years-
surgery is probably of benefit.
A 10 year dog may be better managed on tablets. Numerous methods are described and can vary
depending on the cause and
site of compression - plates, dorsal and ventral laminectory, vertabral body screws etc. Treatment is
aimed at stabilisation and
decompression of the effected section of the spinal cord. Neurological deterioration can occur
subsequent to surgery (months
or years later) due to invovement of an adjacent disc space. Prognosis - of affected dogs is as varied
as their vertabral column
lesions and neurological deficits. In general the more severe the neurological dysfunction, the less
favourable the prognosis.
Post surgical improvement depends on the elimination of further injury to the spinal cord and
remyelination of the damaged
nerve tissue.

Genetics - A simple recessive mode has been suggested in the Great Dane and Dobermann. Higher
incidents are seen in males.
An autosomal recessive mode for the Borzoi (generally affects older adults) has also been suggested.
However there appears to
be a gender influence as well (females are primarily affected in the Borzoi).

References: Veterinary Neuroanatomy and Clinical Neurology, De Lahunta 1983 Textbook of Small
Animal Surgery, Newton
& Nunamaker 1985 Current Techniques in Small Animal Surgery, Bojrab 1983 Textbook of
Veterinary Internal Medicine,
Ettinger 1989 Canine and Feline Endocrinology and Reproduction, Feldman and Nelson 1987