A 2-year-old, intact female Pekingese was presented with a 2-month history of progressive tonic-clonic seizures and left side head tilt. The dog was diagnosed as intracranial arachnoid cyst (IAC) that was located in the quadrigeminal cisterna based on the physical, neurological examinations and magnetic resonance imaging (MRI) of the brain. Medical management using corticosteroids, diuretics, and anticonvulsants was initiated and long term follow-up (6 years) was made. Serial MRI demonstrated elevated occipital lobe compression rate (8%) during the follow-up periods. This case report first describes long term follow-up of the clinical, diagnostic and therapeutic outcome of IAC in a dog.

Key words: Dog, Intracranial arachnoid cyst, Medical management, MRI