What is lumbosacral syndrome?
The term cauda equina syndrome, is Latin for "horse's tail." At this level of the lower spine, the spinal cord changes shape from a tubular structure to a collection of large nerves that have the appearance of a horse's tail.
Cauda equina syndrome or lumbosacral syndrome is a disease that occurs at the lumbosacral junction in the lower back. 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. Cauda equina syndrome or lumbosacral syndrome is a condition caused by the narrowing of the spinal canal and results in compression of the spinal nerve roots (nerves that exit the spine).
What causes lumbosacral syndrome?
Narrowing of the spinal canal and pressure on the nerves that exit the spine cause the clinical signs. This pressure may be due to a narrowed spinal canal caused by arthritis, intervertebral disc herniation, an infection in the disc, trauma, congenital malformation, or a spinal tumor. The most common causes are arthritic degeneration and intervertebral disc herniation.
What are the clinical signs of lumbosacral syndrome?
When instability exists along the spine, abnormal movement occurs. This causes inflammation of the spinal cord and muscles in the affected area. Dogs with lumbosacral syndrome are in pain. When pressure is applied to the muscles in the lower back, many dogs will cry or move away. Some dogs may be 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, due to muscle atrophy (loss of muscle). Other dogs will develop fecal or urinary incontinence, and some will mutilate their feet or tail with incessant chewing.
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 lumbosacral syndrome diagnosed?
Radiographs (X-rays) will generally reveal non-specific 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.
Regardless of radiograph findings, if clinical signs are suggestive of lumbosacral syndrome, advanced imaging such as MRI or CT is recommended to make a diagnosis. A myelogram (injection of contrast material around the spinal cord) may rarely be used if MRI or CT isn’t available, but it is not preferred.
What is the treatment?
Treatment of lumbosacral syndrome involves either conservative medical treatment or surgical intervention. This is dependent upon the duration and severity of the signs and owner preferences as surgery intervention is costly.
If your dog is overweight, weight reduction will be an important part of the conservative treatment. Any disorder of the back is aggravated by excessive body weight.
"Strict rest is an important part of treatment for any back problem."
Strict rest is essential to the success of medical treatment for any back problem. Cage rest is preferable but confinement in a small fenced run or small room is acceptable. Anti-inflammatory drugs (e.g., meloxicam, brand name Metacam®) and pain relievers (e.g., gabapentin) will often give temporary pain relief and may improve clinical signs. Although infection in the disc is not a common cause of lumbosacral syndrome, antibiotics are required in these cases. An infection of this nature usually requires four to eight weeks of therapy.
If conservative management is unsuccessful, there is recurrent pain, or there are neurological signs (e.g., weakness or paralysis), surgical treatment is necessary. When an intervertebral disc ruptures, many dogs will become uncoordinated or weak when they walk, or become paralyzed in the rear legs. If this occurs, a surgical procedure called a dorsal laminectomy is necessary to relieve the pressure of a bulging or ruptured disc on the spinal cord. Surgical exploration allows identification of a spinal tumor or 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.
