Polymicrogyria in Standard Poodles

Background Polymicrogyria is a disorder of cerebrocortical migration resulting in increased numbers of small, disorganized gyri. This disorder occurs in Standard Poodles and in cattle. Objectives To describe the clinical, electroencephalographic, imaging, and histopathologic features in poodles with polymicrogyria. Animals Five Standard Poodles with histologically confirmed polymicrogyria. Methods Retrospective case series. Cases were obtained by personal communication with 1 of 2 authors (TJVW, DPO). Results All dogs had cortical blindness and other neurologic abnormalities including gait and behavioral changes. Magnetic resonance imaging of 3 dogs showed multiple disorganized gyri, which were especially apparent on T2-weighted dorsal plane images. Electroencephalogram (EEG) of 1 dog revealed epileptiform discharges, including both spike and spike and wave discharges with voltage maximum potentials over the parietal/occipital region. The EEG supported that the repetitive behavior displayed by the dog was a complex partial motor seizure. One dog had concurrent hydrocephalus. All dogs had occipital lobe involvement and 2 dogs had involvement of other lobes. Clinical Importance The cases presented here demonstrate a larger age range (7 weeks to 5 years) and a decreased frequency of associated hydrocephalus when compared with the previous report.