Chiari-like malformation (CM) is a condition caused by a mismatch between the skull and brain size. In affected dogs, the brain is too large for the skull, which is abnormally small. This mismatch causes compression at the opening between the skull and the spine, restricting cerebrospinal fluid (CSF) flow around the spinal cord.
As a result, fluid-filled cavities (known as syrinxes) may form within the spinal cord — a condition called syringomyelia (SM).
CM/SM is most commonly seen in Cavalier King Charles Spaniels, but it can also affect several other breeds, including:
- Staffordshire Bull Terriers
- Griffon Bruxellois
- Maltese
- Yorkshire Terriers
- Chihuahuas
- Papillons
- Pomeranians
- Affenpinschers
- Havanese
- Boston Terriers