Acute Onset of Hypertensive Encephalopathy in a Dog with Right Adrenal Pheochromocytoma and Neoplastic Invasion of the Caudal Vena Cava: Case Report and Review of the Literature

Background: Canine pheochromocytomas are rare tumors of adrenal medulla. Clinical signs are often vague, resulting of intermittent catecholamine over secretion or neoplastic invasion of adjacent structures. Case Description: A 12 years old Epagneul Breton dog with a one-year history of chronic kidney disease, was examined for acute onset of severe neurological signs. Based on clinical and instrumental data, hypertensive encephalopathy was suspected. Cardiac and abdominal ultrasound were performed. Severe hypertensive cardiopathy and a right adrenal gland mass with invasion of caudal vena cava were diagnosed. Computed tomography imaging confirmed the suspect of invasive malignant neoplasia. Emergency pharmacological therapy was started to reduce systemic pressure, improve clinical signs, and stabilize the dog in view of surgical resolution. After initial improvement, patient conditions abruptly worsened, and euthanasia was elected. Histology examination confirmed a right adrenal pheochromocytoma, with caval invasion. Conclusion: To authors conclusions, acute hypertensive encephalopathy is a peculiar manifestation for pheochromocytomas. Ultrasound is a useful, and rapid test to suspect pheochromocytoma as it can detect adrenal alterations, caval invasion, metastasis, and cardiac sequelae consistent with the condition. Pheochromocytoma can mimic multiple affections, and be misinterpreted, especially when a concurrent disease has already been diagnosed. Veterinarians need to be aware that comorbidities could mask clinical signs and delay diagnosis. Furthermore, this clinical case remind to include pheochromocytoma also in the differential diagnosis of dogs with an acute onset of severe neurological signs. [Open Vet J 2024; 14(7.000): 1716-1725]