Small Animal Dermatology, 3rd edition

chapter 26 Hyperadrenocorticism, Canine............................

DEFINITION/OVERVIEW

 Spontaneous hyperadrenocorticism (HAC): disorder caused by excessive production

of cortisol by the adrenal cortex.

 Two forms of spontaneous hyperadrenocorticism: pituitary dependent (PDH) and

adrenal dependent (ADH).

 Iatrogenic hyperadrenocorticism results from excessive exogenous administration of

glucocorticoids.

 Clinical signs are a result of the deleterious effects of elevated circulating cortisol

concentrations on multiple organ systems.

ETIOLOGY/PATHOPHYSIOLOGY

 PDH:
85–90% of cases of naturally occurring HAC
Caused by uncontrolled proliferation (tumor) of the basophilic or chromophobic

cells of the pars intermedia and the pars distalis of the pituitary gland, resulting

in hypersecretion of adrenocorticotrophic hormone (ACTH)

Hypersecretion of ACTH causes bilateral adrenocortical hyperplasia

Most tumors are small (microadenomas); approximately 15% are macroadeno-

mas

Clinical signs are similar; macroadenomas may have associated central nervous

system signs due to a space-occupying mass effect.

 ADH:
10–15% of cases of naturally occurring HAC
Caused by a cortisol-secreting adrenocortical neoplasia (cortical adenoma/

carcinoma)

Approximately 50% of tumors are malignant

Contralateral “normal” adrenal gland atrophies because of excessive cortisol

production by the adrenal tumor.

Blackwell’s Five-Minute Veterinary Consult Clinical Companion: Small Animal Dermatology, Third Edition.
Karen Helton Rhodes and Alexander H. Werner.
©2018 John Wiley & Sons, Inc. Published 2018 by John Wiley & Sons, Inc.

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