Somatotroph pituitary tumors in budgerigars (Melopsittacus undulatus).

A series of 11 pituitary tumors in budgerigars were classified on the basis of their clinical, gross, microscopic, and immunohistochemical characteristics. Affected birds were young to middle-aged. Clinically, neurologic signs--including difficulties flying, ataxia, and blindness--were most commonly reported. Additional clinical signs included weight loss, abnormal feathers or molting, increased respiratory efforts, and exophthalmos. Nine birds were diagnosed with chromophobic pituitary adenomas, and 2 birds had chromophobic pituitary carcinomas. Only 1 tumor was delimited to the pituitary gland; the other 10 variably invaded the brain, skull, and retrobulbar space. Distant metastases were identified in 2 birds. All tumors were immunohistochemically strongly positive for growth hormone, consistent with the diagnosis of somatotroph tumors. The common occurrence and early onset may suggest a genetic predisposition of budgerigars to develop somatotroph pituitary tumors with a high incidence of local invasion and with metastatic potential.

Non-functional pituitary chromophobe adenoma in a calf.

A 5-month-old male calf showed neurological signs, including circling, in-co-ordination, depression, blindness and eventual recumbency. On necropsy, a mass measuring 3.5 x 4.5 x 5 cm was found at the base of the brain, at the level of the pituitary gland. The hypothalamus and optic nerves were compressed by the dorsally expanding mass. Non-functional pituitary chromophobe adenoma was diagnosed from histochemical, immunohistochemical and electron microscopical findings.

Effect of surgical removal of subcutaneous tumors on survival of rats.

Mammary and other subcutaneous tumors were surgically removed from aged Sprague-Dawley rats in an attempt to extend survival. The surgical technique was straightforward, and survival following mastectomy was good (17/21). The number of mammary and pituitary tumors in sexually intact rats and those that had previously undergone ovariectomy were compared. The frequency of mammary tumors was significantly lower in ovariectomized vs sexually intact rats (2/47 vs 24/49), as was the frequency of pituitary adenomas (2/46 vs 27/41). Survival to 630 days of age was higher in ovariectomized than in sexually intact rats (42/47 vs 29/49), although tumors did not contribute significantly to mortality.

Pituitary dependent hyperadrenocorticism in a cat.

A cat that was suspected some insulin resistance was diagnosed as pituitary dependent hyperadrenocorticism from an adrenocorticotropic hormone (ACTH) stimulation test, dexamethasone suppression test and measure of endogenous plasma ACTH concentration. Histopathological examination revealed chromophobe adenoma in pituitary gland and hyperplasia in adrenal cortex.

Pituitary-dependent hyperadrenocorticism in a cat.

Pituitary-dependent hyperadrenocorticism was diagnosed in a 9-year-old, male castrated cat that had polyuria, polyphagia, pendulous abdomen, truncal hair loss, congestive heart failure, and insulin-resistant diabetes mellitus. Results of pituitary-adrenal function testing revealed inadequate serum cortisol suppression following dexamethasone administration, exaggerated serum cortisol responses after exogenous ACTH stimulation, and high plasma ACTH concentrations. The pathologic findings of bilateral adrenocortical hyperplasia and a pituitary adenoma that immunostained well for ACTH-related peptides confirmed pituitary-dependent hyperadrenocorticism.

Non-dexamethasone-suppressible, pituitary-dependent hyperadrenocorticism in a dog.

A 5-year-old female dog with hyperadrenocorticism was determined to have pituitary-dependent hyperadrenocorticism even though plasma cortisol concentrations were not suppressed after high-dosage dexamethasone administration. The diagnosis was based on a supranormal response of plasma cortisol to ACTH administration and a lack of suppression of plasma cortisol concentration after administration of 0.1 mg of dexamethasone/kg. Although a higher dosage of dexamethasone (1 mg/kg) did not cause suppression of plasma cortisol, plasma ACTH concentrations in the dog were increased above those in clinically normal dogs, supporting a diagnosis of pituitary-dependent hyperadrenocorticism. During treatment with mitotane, the dog became unconscious and died. Necropsy revealed a pituitary tumor that had compressed and displaced the hypothalamus. Although high-dosage dexamethasone suppression tests often are useful in the differential diagnosis of hyperadrenocorticism, a lack of suppression of plasma cortisol does not necessarily exclude pituitary-dependent hyperadrenocorticism.

Pituitary tumour causing multiple endocrinopathies in a dog.

A 9-year-old male Boxer with signs of lethargy, weight gain, polyuria, polydipsia, eosinopaenia and lymphopaenia was diagnosed as having hyperadrenocorticism. Concurrent central diabetes insipidus was diagnosed using a water deprivation test and antidiuretic hormone response test. A contrast radiographic technique was used to outline a pituitary mass. A chromophobe adenoma and secondary hypothyroidism were found on post-mortem examination.

Annulate lamellae in spontaneous prolactin cell adenomas of the rat pituitary.

Electron microscopy of 13 pituitary prolactin cell adenomas, removed at autopsy from untreated female aging Long-Evans rats, revealed the presence of annulate lamellae in 3 tumors. No annulate lamellae were detected in 10 non-tumorous pituitary glands of adult untreated rats. Direct continuity was demonstrated between annulate lamellae and rough-surfaced endoplasmic reticulum, consistent with the assumption that annulate lamellae may originate from and/or transform to endoplasmic reticulum membranes. The results indicate that annulate lamellae are not uncommonly formed in prolactin cell adenomas, i.e. in cells which have a faster growth rate than non-tumorous adenohypophysiocytes.