Nicardipine infusion for intraoperative hypertension control in three dogs undergoing adrenalectomy for pheochromocytoma

Canine pheochromocytoma can cause severe intraoperative hypertension due to excessive catecholamine release, which can make anesthetic management challenging. In human medicine, nicardipine, a dihydropyridine calcium channel blocker, is used to manage intraoperative hypertension as it causes minimal myocardial depression and promotes hemodynamic stability. The use of a nicardipine constant rate infusion (CRI) in three dogs undergoing adrenalectomy for pheochromocytoma is described. Nicardipine was given as a loading dose (20 μg kg -1 over 10 minutes) followed by a CRI (40 μg kg -1 hour -1 ) after a hypertensive event, defined as systolic arterial blood pressure (SAP) > 160 mmHg. Attenuation of the magnitude and duration of hypertensive episodes was noted during nicardipine CRI, with peak SAP lower in Case 1, episode duration shorter in Case 2, and SAP remaining below 160 mmHg in Case 3 despite marked sinus tachycardia (heart rate > 200 beats minute -1 ). Although hypertensive episodes were not completely abolished, a reduction in their severity and duration was observed during nicardipine infusion. All three dogs recovered and were discharged within 3 to 5 days. Histopathologic examination confirmed pheochromocytoma in all cases. These findings suggest that nicardipine CRI may be an option for managing intraoperative hypertension in dogs with pheochromocytoma. Further studies are needed to fully integrate nicardipine into multimodal antihypertensive protocols during adrenalectomy in dogs.