Cauda equina is Latin and means "horse tail." It refers to the bundle of nerve roots that leave the lower spine and resemble a horse's tail. The spinal canal, through which the spinal cord and nerves pass, sometimes narrows and then compresses the nerves. The most common spot for this narrowing to occur is at the lumbosacral joint, where the spine meets the pelvis. Spinal canal narrowing at that joint is referred to as lumbosacral stenosis, and the condition resulting from these compressed spinal nerve roots is called cauda equina syndrome.

The narrowing within the spinal canal can happen at any age. It is most often caused by arthritis or intervertebral disc herniation, but traumatic injury, congenital malformation (born with it), or tumor growth can also be involved.

Pain is the most common clinical symptom of cauda equina syndrome. Dogs may show some stiffness that leads to difficulty in walking, climbing stairs, getting on furniture, wagging the tail, positioning to defecate, or getting into a car. If the condition worsens, one or both back legs may become weak. Some dogs may cry out in pain when trying to move. If the nerves are completely compressed, the dog may not be able to control their urinating or defecating. Large breed dogs that are active are the most commonly affected. However, it has been seen in smaller dogs and even cats. The most common breed affected are German shepherds.

Cauda equina syndrome is diagnosed based on physical exam, history and X-rays. Referral to a neurologist is sometimes recommended where they can perform MRI, CT, and other more specific imaging of the spinal cord.

Treating lumbosacral stenosis is variable, depending on severity of the disease. If only mild, strict rest with anti-inflammatories can be sufficient. Surgery is reserved for dogs with severe clinical signs. Surgery is performed on the spinal canal to help decompress the pressure from the narrowing.

Dogs with mild signs have a good prognosis as they can be medically treated. Severely affected dogs have a poor prognosis as most do not regain control of their bladder or defecation ability, even after surgery.

Dr. Allani Delis, DMV, is a veterinarian at St. Francis Pet Clinic in Ketchum. 

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