Chiari-like malformation (CM) the most common cause of foramen magnum obstruction and syringomyelia in dogs. Syringomyelia (SM) is a disease of the spinal cord typified by fluid filled cavities, or syrinxes, within the spinal cord substance but it can cause pain by disrupting the cerebrospinal fluid (CSF), in the brain CM is a condition characterized by the mismatch of size between the brain and the skull. CM is very widespread in many Toy breed dogs and has been studied in the Cavalier King Charles Spaniel and the Griffon Bruxellois (Brussels Griffon) and Chihuahua. As many as 95% of Cavalier King Charles Spaniels may have CM. It is worldwide in scope and not limited to any country, breeding line, or kennel, and experts report that it is believed to be inherited CM is so widespread in t