There are many underlying causes of cauda equina syndrome. Normal wear and tear with aging results in deterioration of the intervertebral disks (disk degeneration). Although some older patients can show clinical signs, more often the deterioration progresses without any problems or symptoms. In some pets, this deterioration is accelerated and middle-aged patients can show clinical signs.
Occasionally, a specific traumatic event may cause disk herniation. If the disk between the lowest lumbar vertebra and the sacrum (the lumbosacral disk) is bulging, the cauda equina may become compressed. This compression may occur over the course of many months and thus symptoms may be gradual and often mistaken for arthritis.
Disease processes that can compress the cauda equina nerves include degenerative arthritis of the spine, subluxation (sinking of the sacral vertebrae), congenital deformity of the bones, and disk herniation.
Degenerative lumbosacral stenosis, the most common form of cauda equina syndrome, is associated with a number of pathologic changes in the spine that result in the compression of nerves. Thickening of the intervertebral disk, thickening of the ligament within the spinal canal (interarcuate ligament), thickening of the joints of the spine due to arthritis, and subluxation/mal alignment of the spinal bones are common with this condition.
Other diseases and medical problems that can mimic lumbosacral stenosis, and thus cause cauda equina syndrome, include degenerative spinal cord disease (myelopathy or neuropathy), muscle diseases (myopathy), infection of the lumbosacral disk (diskospondylitis), myasthenia gravis, blood clot in the arteries of the hind limbs, hip dysplasia, cruciate ligament rupture, and polyarthritis. As there are many causes of cauda equina syndrome, it is important that you get a proper diagnosis from your veterinarian, as the underlying cause may be treatable and can vary in degree of seriousness in terms of your pet’s long-term health.