Suspected cerebral salt wasting syndrome secondary to traumatic brain injury in a dog.

Objective: To describe a dog with suspected cerebral salt wasting syndrome (CSWS) secondary to traumatic brain injury (TBI).

Case Summary: A 2-month-old intact male Chihuahua-American Pitbull Terrier mix weighing 1.94 kg presented to a veterinary teaching emergency room after suffering bite wound-penetrating trauma to the head. Treatment was initiated with hyperosmotic agents, fluid resuscitation, and analgesia. The dog's neurologic dysfunction warranted hospitalization and continuous monitoring. Within 24 hours, the dog developed hyponatremia (133 mmol/L compared to 143 mmol/L on presentation [reference interval 142-149 mmol/L]). As the dog had concurrent tachycardia, increase in urine sodium concentration, polyuria, and weight loss, a diagnosis of cerebral salt wasting was suspected. A 2% hypertonic saline constant rate infusion was administered for volume replacement, and the patient showed improvement in clinical signs and blood sodium concentration. The dog was discharged on Day 5. Recheck examination showed significant neurologic improvement with sodium just below the low end of the reference range (141 mmol/L [reference interval 142-149 mmol/L]).

New Or Unique Information Provided: This is the first description of suspected CSWS in veterinary medicine. Hyponatremia is a common finding in critically ill neurologic people, including those with TBI, and is typically associated with either syndrome of inappropriate antidiuretic hormone or CSWS. As treatment recommendations for syndrome of inappropriate antidiuretic hormone and CSWS are diametrically opposed, identifying the presence of hyponatremia and distinguishing between these 2 clinical entities is critical for improving patient care for those with TBI. This case highlights the characteristics and clinical progression regarding the diagnosis and management of suspected CSWS.