Canine phaeochromocytoma: a guide to diagnosis and treatment

Abstract

Phaeochromocytomas are neuroendocrine tumours arising from chromaffin cells of the adrenal medulla. Clinical signs are primarily associated with excessive catecholamine secretion and, to a lesser extent, with the space-occupying or invasive nature of the tumour. The diagnosis of phaeochromocytoma relies on clinical suspicion, biochemical testing, diagnostic imaging and histopathology. Biochemical testing mainly depends on the measurement of levels of plasma or urinary metanephrines, with normetanephrine demonstrating superior diagnostic performance compared to metanephrine. Adrenalectomy is the treatment of choice, but may not be possible in cases with extensive local invasion, concurrent disorders or distant metastasis. Contrast-enhanced computed tomography is recommended for surgical planning and metastasis screening. Vascular invasion is frequently observed, yet surgery remains a viable option in many cases. Recent studies question the necessity of alpha-blockade before surgery, and randomised controlled clinical trials are necessary to evaluate this. Long-term survival is often seen in dogs that survive the perioperative period. For patients in which surgery is not deemed feasible, medical treatment with tyrosine-kinase inhibitors may be considered. Given the current scarcity of effective medical treatment, there is an urgent need to identify novel therapeutic options. This review provides recommendations on the diagnosis and management of canine phaeochromocytoma.