Surgical treatment available for Wobblers
Antonio M. Cruz
Wobbler syndrome encompasses a group of diseases characterized by
gait instability. One of these diseases comes under the name of
cervical vertebral stenotic myelopathy, producing spinal cord
compression at the neck level. This is a disease characterized by
an abnormal gait in the front and/or hind legs, usually worse in
the hind.
It is referred to as “wobbler” syndrome as the horse may seem
wobbly when walking or exercising. The severity of the observed
signs varies among horses. Some horses may seem to have
a stiff neck, appear weak or “lazy”, stumble more than normal, or
give missteps. Others may be reluctant to rise or fall easily.
These horses suffer from “ataxia” — a loss of the sense of where
their feet are placed — and may appear
“drunk” as the horse lacks perception of where its limbs are.
The etiology of this condition has been linked to osteochondrosis
and to nutritional factors including mineral imbalances. The
potential inherited nature of this disease has been widely
debated. To date, no single cause of the condition has been
identified but in growing animals it is believed that a strong
dietary component is involved in this disease.
Brad and Debbie Waekens (right) brought Zippy, then a yearling,
to the OVC suffering from severe ataxia. A
team of veterinarians, Drs. Antonio Cruz, Scott Weese, and Dan
Kenney (left to right) and neurologist Dr. Smith-Maxie diagnosed
Zippy.
With the help of Dr. James Robertson, of Ohio State University,
surgery was performed that involved fusing the affected vertebrae
in the young horse’s neck. Over a year later Zippy is steady and
comfortable and looks as if he will be able to pull his family in
a carriage. While the success of the surgical treatment is based
on a number of factors, across North America a reported
improvement in 75 % of the cases is encouraging.
Diagnosis
It is important to recognize the signs of wobbler syndrome and
identify an affected horse early to give your horse the best
chance to heal. Since the clinical condition known as “wobbler”
encompasses spinal cord compression as well as other conditions
causing ataxia, the collection and examination of the
cerebrospinal fluid (CSF) is essential. Other differentials
include Equine Protozoal Myeloencephalitis (EPM), a neurological
form of rhinopneumonitis and traumatic injuries. The perception that
the problem is increasing in the horse population may actually be
due to an increased awareness, as well as improved expertise in
applying more sophisticated diagnostic methods.
To correctly diagnose your horse a veterinarian will perform a
neurologic examination and identify the location of the lesion
(i.e. brain, spinal cord). Further diagnostic tests will be
required, including the radiography (x-ray) of the cervical spine
and performing a contrast study of the spinal canal (myelogram)
under general anesthesia. This is currently only available in
Ontario at the Ontario Veterinary College (OVC).
A myelogram involves the injection of a special contrast media
around the spinal cord immediately followed by radiographs. The
contrast media will highlight the roof and floor of the spinal
canal allowing a view of any significant narrowing.
The development of low-toxicity contrast media has diminished the
side effects and the rate of complication associated with this
procedure. A cerebrospinal fluid (CSF) sample will be collected
prior to the myelogram. The CSF will be submitted to the university
laboratory for routine examination as well as to a Kentucky
laboratory for EPM testing.
Treatment
A wobbler left untreated may deteriorate to the point of injuring
itself or others, especially when struggling to rise. In the
short term, medical treatment for subtly affected animals, along
with stall rest, may provide relief. In the long term, often the
animal will relapse when allowed unrestricted exercise or when
placed in training.
Until now, most wobblers were euthanized. However, horse owners
have demanded a better approach to treating these animals. This
has resulted in a more widespread acceptance of surgical
treatment. These techniques are now being demonstrated
successfully at the Ontario Veterinary College (OVC), Large
Animal Clinic.
