Chiari-Like Malformation in Dogs

Abstract

The Chiari I malformation in humans and Chiari-like malformation (CLM) in dogs is a condition in which the cerebellum descends out of the foramen magnum affecting normal cerebrospinal fluid (CSF) flow. It is considered to be a developmental abnormality and is commonly confused with many other conditions. Chiari-like malformation in dogs affected approximately 85% of Cavalier King Charles spaniels evaluated, as reported in the most recent studies. The specific cause has not been determined; however, because of an abnormal shape or reduced skull size in the caudal occipital region, part of the cerebellum is forced through the foramen magnum, altering CSF flow patterns. Changes in CSF dynamics result in an abnormal accumulation of fluid within the substance of the spinal cord called a “syrinx.” The diagnosis of CLM in dogs and Chiari type I in humans can only be confirmed by magnetic resonance imaging (MRI), which is essential for determining the cause of syringomyelia. Current concepts in the diagnosis and treatment of Chiari-like malformation in dogs will be discussed.