Hypernatremia most commonly is associated with water loss in excess of sodium or salt gain (typically associated with restriction of access to water). Most of the signs of hypernatremia arise from the central nervous system; the more rapid the development of hypernatremia, the more severe the neurologic signs are likely to be. Anorexia, lethargy, vomiting, muscular weakness, behavioral changes, disorientation, ataxia, seizures, coma, and death have been identified in dogs and cats with hypernatremia and hypertonicity.