To understand cauda equina syndrome and how it affects your pet, it is important to understand the anatomy of the spine. The spinal cord is the network of neurons (nerve cells) that carries motor and sensory signals to and from the body. The spinal column itself serves to protect the spinal cord and consists of bones that house the spinal cord.
A dog’s spinal column consists of 27 bones (vertebrae), not including those in the tail. Intervertebral disks are located between the bones of the spinal column and allow smooth movement while also acting as a shock absorber. Each disk consists of an outer fibrous ring (annulus fibrosus) that surrounds inner pocket of gelatinous material (nucleus pulposus). Ligaments and many muscles support each of the vertebrae. Each disk is located beneath the spinal cord, where each of the spinal nerves exits the spine.
The spinal cord ends in your dog’s lower back, and nerves to the hind limbs, bladder, rectum, and tail extend off the end of the spinal cord and exit the spine to their respective areas. The area where all of the nerves come off the terminal spinal cord looks like the tail of a horse. In Latin, horse translates as equus, hence this region is called the cauda equina.