Cauda Equina Syndrome in Canines

In cauda equina syndrome, dogs develop pain in their lower back. This is often due to problems with the intervertebral discs in the spine, though there are some less common causes as well. Depending on how severe the problems are, dogs may recover on medical treatment or they may require surgery.

What is cauda equina syndrome?

The 'cauda equina' ('horse tail' in Latin) is the anatomical term for the nerves at the very end of the spinal cord. Above the cauda equina, the spinal cord is a tubular structure that runs through a channel in the vertebrae as shown in the animation below. The bony vertebrae protect the spinal cord from harm, and there are discs between the vertebrae that cushion the bones as they move in relation to each other.

At the very end of the spine, there is a junction between the last 'lumbar' vertebra of the lower back and the sacrum (the part of the spine that attaches to the pelvis). At this level, the spinal cord becomes a collection of long nerve fibres that travel to the dog's hindquarters and tail. Together, these nerve fibres look a bit like a horse's tail, hence the name 'cauda equina', as 'cauda' means tail and 'equina' means horse.

In cauda equina syndrome, the nerves in this area become compressed. This is most often due to a condition called 'lumbosacral stenosis', in which the spinal canal is narrowed at the level of the lower back, often as a result of disc disease or arthritis.

Lumbosacral stenosis can affect any dog, but it is most common in large breed dogs such as German Shepherds who are middle-aged or older. While lumbosacral stenosis is the most common cause of cauda equina syndrome, other potential causes include tumours, fractures or infection.

What are the signs of cauda equine syndrome?

Typically, dogs with cauda equina syndrome will show signs of lower back pain. Your dog may be less keen to jump up (e.g. into the car) or climb stairs, and they may show signs of pain if they do so. You may see them carrying their tail lower than normal or wagging it less, and they might also show discomfort while defecating. Hind limb weakness or scuffing the back paws are other potential signs. When the disease is more severe, dogs may show incoordination, urinary or faecal incontinence, and potentially even paralysis of the back legs.

These symptoms can be caused by a range of other diseases, so your vet will need to examine your dog and carry out some tests to diagnose cauda equina syndrome and establish the cause. These tests may include X-rays, CT or MRI scans.

How is cauda equine syndrome treated?

The best treatment depends on the cause of your dog's symptoms and how severe they are. If the signs are relatively mild, or if an anaesthetic and surgery wouldn't be in your pet's best interests, your vet may advise treating conservatively with pain medication and rest. In this case, you may need to make adjustments round your home so that your dog does not have to jump up or use steps. Your vet will advise on how much gentle exercise your pet is allowed to do while they are recovering. If your dog is overweight, weight loss will help their mobility.

If your dog's symptoms are more severe, or if they do not improve with rest, your vet may advise surgery. The exact procedure used will depend on your dog's condition, but if disc disease is the problem, your vet may advise surgery to decompress the spinal cord as in the animation below:

Your vet will be able to advise you on the likely prognosis if you opt for surgery. Following surgery, it is important to follow your vet's recommendations regarding aftercare. Strict rest is usually advised in the immediate recovery period.

Animations ©Medi-Productions