Lumbosacral Disease (Cauda Equina Syndrome) in Dogs

By Malcolm Weir, DVM, MSc, MPH; Tammy Hunter, DVM; Ernest Ward, DVM

What is lumbosacral disease?

Lumbosacral disease, also known as cauda equina syndrome, is a condition affecting the lumbosacral junction in the lower back. The term lumbo refers to the lumbar vertebrae, the bones in the lower part of the spinal column. The term sacral refers to the sacrum, which is part of the spine that joins the lumbar spine and the pelvis.

"Lumbosacral disease is a condition caused by the narrowing of the spinal canal and results in compression of the spinal nerve roots (cauda equina)."

Lumbosacral disease is a condition caused by the narrowing of the spinal canal and results in compression of the spinal nerve roots (cauda equina). The term cauda equina 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.

What causes lumbosacral disease?

The clinical signs of lumbosacral disease are caused by narrowing of the spinal canal and pressure on the nerves that exit the spine. The narrowed spinal canal may be caused by arthritis, intervertebral disc herniation, an infection in the disc, trauma, congenital (born with) malformation, or a spinal tumor. The most common causes are arthritic degeneration and intervertebral disc herniation.

What breeds or ages of dog are affected?

Lumbosacral disease occurs most often in middle-aged to older large-breed dogs such as the German shepherd. It has also been reported in the Airedale terrier, boxer, English springer spaniel, golden retriever, Great Dane, Irish setter, and Labrador retriever. It may occasionally occur in small-breed dogs and may be more common in males.

What are the clinical signs of lumbosacral disease?

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 disease 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 fall to their knees if their tail is lifted sharply. Occasionally, dogs develop weakness or lameness in the rear legs, due to muscle loss (atrophy). Other dogs 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 walking or it may be paralyzed in the rear legs.

How is lumbosacral disease diagnosed?

X-rays (radiographs) generally reveal non-specific arthritic changes at the lumbosacral junction. However, such changes are 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.

"Advanced imaging such as MRI or CT is recommended to make a diagnosis."

If clinical signs are suggestive of lumbosacral disease, advanced imaging such as MRI or CT is recommended to make a diagnosis, regardless of x-ray findings. 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 disease involves either conservative medical treatment or surgical intervention. Treatment is dependent on the duration and severity of the signs and owner preferences, as surgery intervention is costly. If your dog is overweight, weight reduction is an important part of the conservative treatment. Any disorder of the back is aggravated by excessive body weight.

Strict rest is essential to the success of medical treatment for any acute back problem. Cage rest is preferable, but confinement in a small, fenced run or small room may be acceptable. Anti-inflammatory drugs (e.g., meloxicam, brand name Metacam®) and pain relievers (e.g., gabapentin) often give temporary pain relief and may improve clinical signs. If there is infection in the disc (discospondylitis), antibiotics are required, but infection is not a common cause of lumbosacral disease. If discospondylitis is diagnosed, it usually requires 4 to 8 weeks of therapy.

If conservative management is unsuccessful, if there is recurrent pain, or if there are neurological signs (e.g., weakness or paralysis), surgical treatment is necessary. When an intervertebral disc ruptures, many dogs 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.

"Strict rest is essential to the success of medical treatment for any acute back problem."

Once the pressure is relieved, pain relief and improved rear leg function is expected. The prognosis with surgery often depends on how severe the signs are and how long the disease has been affecting the dog. Any permanent damage to the nerves will not be reversed. If fecal or urinary incontinence has developed, surgery will not likely improve these issues. ain relievers or anti-inflammatory drugs may still be needed, depending on the dog’s condition after surgery.

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