Concurrent pituitary and adrenal tumors in dogs with hyperadrenocorticism: 17 cases (1978-1995).
OBJECTIVE
To describe the clinicopathologic characteristics of dogs with hyperadrenocorticism and concurrent pituitary and adrenal tumors.


METHODS
Retrospective study.


METHODS
17 client-owned dogs.


METHODS
Signalment, response to treatment, and results of CBC, serum biochemical analysis, urinalysis, endocrine testing, and histologic examinations were obtained from medical records of dogs with hyperadrenocorticism and concurrent adrenal and chromophobe pituitary tumors.


RESULTS
On the basis of results of adrenal function tests and histologic examination of tissue specimens collected during surgery and necropsy, concurrent pituitary and adrenal tumors were identified in 17 of approximately 1,500 dogs with hyperadrenocorticism. Twelve were neutered females, 5 were males (3 sexually intact, 2 neutered); and median age was 12 years (range, 7 to 16 years). Hyperadrenocorticism had been diagnosed by use of low-dose dexamethasone suppression tests and ACTH stimulation tests. During high-dose dexamethasone suppression testing of 16 dogs, serum cortisol concentrations remained high in 11 dogs but decreased in 5 dogs. Plasma concentrations of endogenous ACTH were either high or within the higher limits of the reference range (12/16 dogs), within the lower limits of the reference range (2/16), or low (2/16). Adrenal lesions identified by histologic examination included unilateral cortical adenoma with contralateral hyperplasia (10/17), bilateral cortical adenomas (4/17), and unilateral carcinoma with contralateral hyperplasia (3/17). Pituitary lesions included a chromophobe microadenoma (12/17), macroadenoma (4/17), and carcinoma (1/17).


CONCLUSIONS
Pituitary and adrenal tumors can coexist in dogs with hyperadrenocorticism, resulting in a confusing mixture of test results that may complicate diagnosis and treatment of hyperadrenocorticism.
D000236:Adenoma / Q000150:complications / Q000662:veterinary; D000304:Adrenal Cortex Function Tests / Q000662:veterinary; D000310:Adrenal Gland Neoplasms / Q000150:complications / Q000662:veterinary*; D000311:Adrenal Glands / Q000000981:diagnostic imaging / Q000473:pathology; D000308:Adrenocortical Hyperfunction / Q000209:etiology / Q000662:veterinary*; D000818:Animals; D002277:Carcinoma / Q000150:complications / Q000662:veterinary; D004283:Dog Diseases / Q000209:etiology*; D004285:Dogs; D005260:Female; D006854:Hydrocortisone / Q000097:blood; D006965:Hyperplasia / Q000662:veterinary; D008297:Male; D010902:Pituitary Gland / Q000473:pathology; D010911:Pituitary Neoplasms / Q000150:complications / Q000662:veterinary*; D011859:Radiography; D012189:Retrospective Studies; D014463:Ultrasonography