A case of narcolepsy-cataplexy associated with distemper encephalitis.

Narcolepsy associated with localized brain lesions is described in a 10-month-old Argentine Dogo. Neurological examination and MRI study suggested an inflammatory lesion of the left frontal lobe. Postmortem examination revealed diffuse encephalitis in the forebrain and marked necrotic lesions in the ventral pontine area. Immunohistochemistry for distemper virus antigen showed positive staining of the cytoplasm of many neurones of the pons and cerebral cortex. The pathological pattern was suggestive of post-vaccinal distemper encephalitis and the localization of the lesions was consistent with the neurological syndrome shown by the animal. At any event, the possibility of coincidental findings of distemper encephalitis and idiopathic narcolepsy must be accounted for.