Hypernatremia and adipsia in a dog.

Primary adipsia and defective osmoreceptor function were diagnosed in a 7-month-old female Miniature Schnauzer. Also, the dog was noted to be dehydrated and to have chronic hypernatremia. On multiple occasions the dog's urine osmolality: plasma osmolality was greater than 4. The dog had inappropriate responses to isoosmotic and hypertonic NaCl infusions. Chlorpropamide administration initiated water intake but the volume was insufficient to avoid hypernatremia. The chronic hypernatremia and dehydration were treated successfully by mixing the calculated maintenance fluid volume in canned food. At 25 months of age, the dog died several days after becoming dehydrated and severely hypernatremic. Astrogliosis and neuronal degeneration were noted in both the thalamic and hypothalamic regions, but were believed to be nonspecific degenerative lesions compatible with seizures and severe dehydration.