Glioblastoma Multiforme with Hypodipsic Hypernatremia in a Seven-Month-Old Golden Retriever.

Primary hypodipsic hypernatremia is a rarely reported disease in dogs. Reported underlying causes associated with this disease in dogs include congenital malformations, encephalitis, intracranial neoplasia, and pressure atrophy of the hypothalamus secondary to hydrocephalus. The dog in this report had an infiltrative neoplastic disorder, likely causing damage to the hypothalamic osmoreceptors responsible for the thirst generation. The neoplastic process was identified histopathologically as glioblastoma multiforme, an unusual tumor to occur in a dog this young. A tumor of the central nervous system causing physical destruction of the osmoreceptors has rarely been reported in dogs and none of the previously reported cases involved a glial cell tumor.