Incidence, Severity and Prognosis Associated with Hypernatremia in Dogs and Cats

BACKGROUND: Hypernatremia has been associated with substantial morbidity and death in human patients. The incidence and importance of hypernatremia in dogs and cats has not been determined. HYPOTHESIS/OBJECTIVES: To describe the incidence of and prognosis associated with hypernatremia in dogs and cats at a university teaching hospital. ANIMALS: A total of 16,691 dogs and 4,211 cats with measured blood or serum sodium concentration. METHODS: Retrospective study. Medical records of animals with a blood or serum sodium concentration measured during a 60‐month period were reviewed to determine the severity of hypernatremia and its associated case fatality rate. Cases with moderate (11–15 mmol/L above the reference range) or severe hypernatremia (≥16 mmol/L above the reference range) were further reviewed. RESULTS: A total of 957 dogs (5.7%) and 338 cats (8.0%) were diagnosed with hypernatremia. Case fatality rates of dogs and cats with hypernatremia was 20.6 and 28.1%, respectively compared to 4.4 and 4.5% with a normal blood or serum sodium concentration (P < .0001). The magnitude of hypernatremia was linearly associated with a higher case fatality rate (P < .0001). Hypernatremia was associated with a higher case fatality rate than hyponatremia. Among the animals with moderate or severe hypernatremia, 50% of dogs and 38.5% of cats presented with community‐acquired hypernatremia, and 50% of dogs and 61.5% of cats developed hospital‐acquired hypernatremia. CONCLUSIONS AND CLINICAL IMPORTANCE: Hypernatremia was found infrequently in this population but was associated with increased case fatality rates in dogs and cats. Presence and severity of hypernatremia might be useful as a prognostic indicator.