Cauda Equina

What is cauda equina syndrome?

Cauda equina syndrome involves the narrowing of the vertebral canal, resulting in compression of the spinal nerve roots. In dogs, this occurs in the space between the last lumbar vertebrae and the start of the tailbone.

The term Cauda Equina comes from Latin words that mean ‘horse’s tail’.  At this level, the spinal cord is no longer a tubular structure. Instead, it’s a collection of large nerves that have the appearance of a horse’s tail.

With this condition, the space between the vertebra isn’t normal, which this puts pressure on the nerves that exit the spine. The cause of the pressure could include:

  • a narrowed spinal canal
  • infection in the disc at the joint
  • trauma
  • a spinal tumour
  • instability at the 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 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 faecal 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 they walk or paralysed in their rear legs.

How is it diagnosed?

X-rays will generally reveal arthritic changes at the lumbosacral junction. If the clinical signs are correct and the initial X-rays indicate cauda equina syndrome, special X-ray studies can be performed. These involve the injection of contrast material around the spinal cord and possibly in the vertebral canal so that pressure on the spinal cord can be detected.

What treatments are available?

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 four to eight weeks of therapy.

If the disc ruptures, many dogs will become uncoordinated when they walk, or they may even become paralysed in the rear legs. If this occurs, surgery is necessary. 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 possible spinal tumour or a narrowing of the spinal canal due to traumatic injury. Once the pressure is relieved, return of rear leg function 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 resolves.

Acupuncture treatment has proven to be effective in relieving this condition. Depending on the cause of the cauda equina, this may be a good pain management option.

Speak with your local Greencross Veterinarian to determine the cause and treatment.