Canine Adrenal Tumors: An Incidental Finding or a Serious Disorder

Dogs with adrenal tumors (AT) present in a variety of ways: from those with severe clinical sigs to those that are apparently asymptomatic. The ATs may be benign or malignant, functional and non-functional. Hormonally active or functional tumors
may arise from the adrenal cortex or the medulla and over secrete mineralocorticoids, glucocorticoids, sex-steroids and catecholamines. Non-functional ATs are often an incidental finding during diagnostic imaging in dogs without clinical signs of adrenal disease and are called incidentalomas. Another differential diagnoses for non-functional AT are myelolipoma, hemorrhage, cysts and metastasis (1).

Cortisol-secreting ATs are the most common. Adenomas and carcinomas are reported to occur with equal frequency, but the differentiation is cumbersome even by histological examination. Carcinomas tend to be larger than 2 cm and are characterized by invasive growth into adjacent blood vessels, but the only straightforward characteristic of a carcinoma is the presence of metastasis (2). Clinical signs and symptoms in dogs with cortisol-secreting ATs are associated with hypercortisolemia and include pu/pd, polyphagia, abdominal enlargement, alopecia and other well-known signs associated with Cushing`s syndrome. It is worthwhile mentioning, that the AT-tissue is only moderately active and therefore the clinical sigs of hypercortisolemia are usually
mild. Especially in large ATs, steroidogenesis tend to be incomplete and instead of cortisol, its precursors are secreted. […]