Hypernatremia is defined as a serum sodium level above the reference range. It is a relatively infrequently encountered electrolyte disturbance in dogs and cats. In one retrospective study (Ueda et al. 2015), 5.7% dogs and 8.0% cats were diagnosed with hypernatremia. It was associated with increased case fatality rates in this population of patients. Understanding hypernatremia requires a comprehension of body fluid compartments, as well as concepts of the preservation of normal body water balance. The animal body maintains a normal osmolality between 280 and 310 mOsm/kg via Arginine Vasopressin (AVP), thirst, and the renal response to AVP; dysfunction of all three of these factors can cause hypernatremia (Mushin et al. 2016). In this post, I present a step-by-step approach to the hypernatremia in canine and feline patients. Further reading is recommended to deepen understanding of the physiology and pathophysiology of sodium and water balance.
The hypernatremia treatment protocol can be downloaded here.
This blog post commences a series of articles on diagnostic and therapeutic approaches to potassium and sodium derangements. This is meant to be a quick reference/guideline for emergency veterinarians, students and technicians. All readers are welcome to leave feedback and comments below.
A 7 year-old male neutered domestic shorthaired 5 kg cat is currently hospitalized for management of an aortic thromboembolism. The cat was diagnosed with hypertrophic cardiomyopathy, left sided congestive heart failure and aortic thromboembolism causing complete lack of motor function in the pelvic limbs. It is being managed with oxygen therapy provided by commercial oxygen kennel, 2 μg/kg/hr fentanyl infusion, furosemide 2 mg/kg q12 hours and 18.75 mg clopidogrel. The cat is being monitored with regular respiratory rate checks and continuous electrocardiogram (ECG). The cat began to show some improvement in pelvic limb motor function. However, 48 hours post initiation of therapy there was a dramatic change in the ECG (Figure 1).