Canine multiple system degeneration (CMSD) is a hereditary movement disorder that affects Kerry Blue Terriers and Chinese Crested Dogs.
Affected pups develop normally until about 4 months of age. Then their head starts to shake when they focus on something, and rather than becoming stronger and more coordinated, they develop exaggerated, goose-stepping movements (cerebellar ataxia). Dogs can function with cerebellar ataxia, but CMSD progresses to a more severe movement disorder by 12-18 months of age. Affected dogs have difficulty even starting a movement and fall frequently. They become incapacitated by 2 years of age.