CAUDA EQUINA, ALSO KNOWN AS THE LUMBOSACRAL SYNDROME
What is the cauda equina syndrome?
This is a disease that occurs at the lumbosacral junction. The term "lumbo"
refers to the lumbar vertebrae. These are the bones in the lower part of the
spinal column. The term "sacral" refers to the sacrum, which is the part of
the spine that joins the lumbar spine and the pelvis.
This disease is also known as the cauda equina syndrome. This term comes from
Latin words that mean "horse's tail". At this level, the spinal cord is no longer
a tubular structure. Instead, it is a collection of large nerves that have the
appearance of a horse's tail.
The lumbosacral syndrome is an instability at this strategic point in the
What causes it?
Pressure on the cauda equina or the nerves that exit the spine is the mechanism
causing the clinical signs. The cause of the pressure may be a narrowed spinal
canal, an infection in the disc at this joint, trauma, a spinal tumor or instability
at this joint.
What are the clinical signs?
When instability exists along the spine, abnormal movement occurs. This causes
inflammation to the nerves leaving the spinal cord and to the muscles in the
immediate area. Affected dogs are in pain and exhibit it in various ways. When
pressure is applied to the muscles in the lower back, many dogs will cry or
move away. Some dogs may be very slow to rise from a lying position because
this movement aggravates the inflamed nerves and muscles. Some will literally
fall to their knees when the tail is lifted sharply. Occasionally, dogs develop
weakness or lameness in the rear legs with muscle atrophy Others have fecal
or urinary incontinence, and some will mutilate their feet or tail with incessant
As the problem progresses, the disc that is located between the last lumbar
vertebrae and the sacrum may rupture. If this happens, the dog will be uncoordinated
when it walks, or it may be paralyzed in the rear legs.
How is it diagnosed?
Radiographs (x-rays) will generally reveal arthritic changes at the lumbosacral
junction. However, this is common in many dogs and may not cause any clinical
signs. If the disc ruptures, there may be evidence of a narrowed disc space
or disc material against the spinal cord. However, these offer only indirect
If the clinical signs are correct and the initial radiographs are suggestive
of the cauda equina syndrome, a special radiographic study, called a myelogram,
is performed. This is the injection of contrast material around the spinal cord
so that pressure on the spinal cord can be detected on subsequent radiographs.
What is the treatment?
If your dog is overweight, weight reduction will be an important part of the
treatment. Any disorder of the back is aggravated by excessive body weight.
Strict rest is also an important part of treatment for any back problem. Cage
rest is preferable, but confinement in a small fenced run or small room is acceptable.
Anti-inflammatory drugs and pain relievers will often give temporary relief.
Although infection in the disc is not a common cause, it should be treated
with appropriate antibiotics if it is present. An infection of this nature usually
requires 4-8 weeks of therapy.
If the disc ruptures, many dogs will become uncoordinated when they walk,
or they may even become paralyzed in the rear legs. If this occurs, surgery
is indicated. The surgical procedure, called a dorsal laminectomy, is to relieve
the pressure of a bulging or ruptured disc from the spinal cord. It also permits
identification of a spinal tumor or a narrowing of the spinal canal due to traumatic
injury. Once the pressure is relieved, return of function of the rear legs is
expected. However, permanent damage to the spinal cord will not be reversed,
and the surgery does not relieve inflammation around the spinal nerves or the
muscles. Continued pain relievers or anti-inflammatory drugs may be needed until
this aspect of the problem finally resolves.
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