An adult male castrated domestic shorthair cat presented to the Cornell University Hospital for Animals following presumptive vehicular trauma. Gaslyte analysis revealed severe hypernatremia (195.1mmol/L) and a mixed acid-base disturbance. Based on these results, as well as specific clinical signs that developed during hospitalization (polyuria and hyposthenuria), trauma-induced central diabetes insipidus was suspected. Parenteral treatment with desmopressin acetate (dDAVP) via subcutaneous injection was initiated at a dose of 4mcg once a day, which improved his clinical signs and thereby confirmed our diagnosis. After four days, parenteral treatment was stopped in favor of beginning topical treatment with dDAVP (0.01% nasal solution). One drop, or 1.5-4mcg, was instilled into the conjunctival sac twice a day. The patient was released to the care of his owner following improvement of his hydration and neurologic status. Due to miscommunication regarding regimen, the patient represented to the Emergency Service eight weeks later obtunded, dehydrated and ataxic. Bloodwork again revealed severe hypernatremia (214mEq/L), which was corrected via intense isotonic fluid therapy and diuresis. Clinical signs, diagnosis, treatment and prognosis of trauma-induced central diabetes insipidus are discussed.