The medical records of 17 dogs diagnosed with spinal arachnoid cysts at North Carolina State University Veterinary Teaching Hospital were retrospectively examined to identify trends in signalment, history, neurological status, treatment, and short- and long-term prognosis. The typical case was that of a nonpainful, progressive ataxia frequently characterized by hypermetria and incontinence. Cysts typically occurred in the dorsal subarachnoid space at the first to third cervical vertebrae of young, large-breed dogs or the caudal thoracic vertebrae of older, small-breed dogs. Although 14 of 15 dogs treated surgically did well in the short term, long-term successful outcomes were achieved in only eight of the 12 dogs that were followed for >1 year. Significant predictors of good, long-term outcome were not identified; however, factors associated with a trend toward a good outcome included <3 years of age, <4 months' duration of clinical signs, and marsupialization as the surgical technique.