Abstract
A 1-year-old neutered male Pekingese was presented for evaluation and further treatment of cluster seizures. The dog had behavioral abnormalities, and a prosencephalic lesion was suspected following neurological examination. The dog showed signs of learning difficulty. Magnetic resonance imaging of the brain revealed a remarkably smooth cerebral cortex with a reduced number of gyri, as well as a cystic lesion associated with the quadrigeminal cistern. A diagnosis of lissencephaly, concurrent with a quadrigeminal cisternal cyst, was made. High-dose and multiple anticonvulsants were necessary to control the seizures. This is the first report of lissencephaly in a Pekingese.