Necrotizing meningoencephalitis associated with cortical hippocampal hamartia in a Pekingese dog

A 4-year-old male Pekingese dog was referred to the clinic with a history o f recurrent seizures and progressive abnormal gait and behavior, which did not respond to treatment. At necropsy, a large cortical defect in the right temporo-parietal cortex, malacia of subcortical white matter, right basal nuclei, and capsula interna, as well as abnormalities of the right hippocam pus were observed. Histological examination of the brain revealed moderate to severe nonsuppurative meningoencephalitis in the left cerebral hemispher e and extensive infarction-like lesions with milder inflammation in the rig ht hemisphere. In the right hippocampus, the pyramidal cells were arranged in a gyrus-like pattern and intermingled with gemistocytic and fibrillary a strocytes. The histopathological features of the inflammatory lesions were consistent with necrotizing meningoencephalitis and resembled those describ ed in so-called Pug dog encephalitis. The hippocampal changes were interpre ted as dysplasia (monolateral hippocampal cortical hamartia), unrelated to clinical signs and necrotizing inflammatory lesions.