This thesis is the cumulation of over a decade of study into the pathogenesis and treatment Chiari-like malformation and syringomyelia (CM/SM) in the cavalier King Charles spaniel (CKCS). Chiari-like malformation is a condition where the brain is too big for the skull and is crushed and pushed out the foramen magnum. This obstructs the flow of cerebrospinal fluid in and out of the head. A consequence of this is that fluid accumulates within the spinal cord forming cavities termed syringomyelia (SM). This fluid often collects in the dorsal horn of the spinal cord - an important area for collating information about pain sensation. The damage can result in signs of severe pain. As the dogs with this condition are a natural occurring example of a disease which also occurs in humans, finding new and effective ways of managing this pain will be relevant for both human and canine sufferers. CM/SM is inherited in the CKCS - as many as 50% have the condition and approximately 35% of affected dogs have clinical signs of pain. Part on the ongoing work in this study is the identification of the genes responsible for CM/SM.