Perioperative Medical Management of Adrenal Neoplasia

Veterinarians are often presented with complex adrenal neoplasia cases that have significant intraoperative challenges, which require the skills of an experienced surgeon. Perioperative evaluation and treatment of these patients can be equally challenging, and successful outcomes require a thorough understanding of the tumor types that affect the adrenal glands, as well as an understanding of appropriate preoperative and postoperative management of these cases. Even when a clinician has a thorough understanding of adrenal neoplasia, definitive preoperative diagnosis can be difficult. Further difficulty can arise when a patient with no obvious outward signs of adrenal disease is diagnosed with an adrenal tumor during abdominal ultrasound for an unrelated condition. These are some of the many factors that make adrenal gland neoplasia a complex but often times rewarding condition to treat. A basic understanding of adrenal gland anatomy and physiology is critical for successful diagnosis and management of adrenal tumors. The adrenal gland is composed of an outer cortex and inner medulla. The cortex consists of the zona glomerulosa, zona fasciculate and zona reticularis, which produce mineralocorticoids (primarily aldosterone), glucocorticoids (primarily cortisol) and sex hormones, respectively. Catecholamines (primarily epinephrine and norepinephrine) are produced by the medulla. Based on the above, the major tumors that are encountered in companion animals include benign and malignant tumors of the cortex that can be cortisol secreting, aldosterone secreting or non-functional. The primary tumor of the adrenal medulla is pheochromocytoma, which leads to excessive circulating levels of catecholamines.