Perianal adenomas and hypertestosteronemia in a spayed bitch with pituitary-dependent hyperadrenocorticism.

Hypertestosteronemia was diagnosed in a spayed bitch with pituitary-dependent hyperadrenocorticism and perianal adenomas. Serum concentrations of cortisol and testosterone decreased after treatment with mitotane was instituted. Excessive testosterone in this dog was thought to have been produced by the adrenal cortex, possibly in response to excessive ACTH concentrations. Development of androgen- or estrogen-responsive tumors in castrated dogs may be an early indication of adrenocortical hyperfunction.

Ultrastructural evaluation of adenocarcinomas derived from apocrine glands of the anal sac associated with hypercalcemia in dogs.

Adenocarcinomas derived from apocrine glands of the anal sac and associated with persistent hypercalcemia in dogs were composed of tumor cells with numerous profiles of rough endoplasmic reticulum, clusters of free ribosomes, and a prominent Golgi apparatus. Neoplastic cells contained microtubules, microfilaments, tonofibrils, and had two types of electron-dense granules. Large lysosomelike dense bodies ranged from 0.6 to 2.2 microns in diameter and had a poorly delineated limiting membrane. Small granules (150-400 nm in diameter) had a sharply delineated limiting membrane with a narrow submembranous space and a homogeneous dense core. These smaller granules usually were located near the apexes of neoplastic cells, whereas the larger granules were situated near the base of cells. Apocrine cells in glands of the anal sac from control dogs that were in the secretory phase were columnar and had large dilated profiles of rough endoplasmic reticulum. Membranes of the endoplasmic reticulum fused with the plasmalemma and appeared to secrete their product directly into the lumens of acini, characteristic of merocrine secretion. Apical blebs of electron-lucent cytoplasm pinched off from nonneoplastic aprocine cells and were released into glandular lumens. Similar electron-lucent cytoplasmic blebs were present at the apexes of tumor cells. Myoepithelial cells were present between the epithelial cells and basement membrane in normal apocrine glands and were absent in neoplasms derived from these glands. Identification of the contents of the secretory-like granules in tumor cells and characterization of the hypercalcemic factor in the plasma or tumor tissue from dogs with this syndrome will help explain the pathogenesis of hypercalcemia associated with malignancy in animals and man.

Hyperthermic treatment of superficial tumors in cats and dogs.

Local current field radiofrequency hyperthermia was applied to 33 superficial tumors in 11 cats and 5 dogs. Squamous cell carcinoma (SCC) in the cat was the most frequent tumor treated. Of 19 SCC in cats, 13 (68%) were reduced completely, combining complete and partial tumor reduction, there was an 89% favorable response to hyperthermia for SCC. A small number of other tumors such as fibrosarcoma in the cat and perianal tumors in the dog were favorably responsive. Local current field hyperthermia (50 C for 30 sec) resulted in destruction of tumor tissue as well as normal tissue. However, tissue destruction did not extend more than 2 or 3 mm from the electrodes. Ulcerative superficial tumors exposed to air rapidly reduced in size, and a dry eschar that developed fell off at 17 to 25 days.

Intranuclear cisternal and vesicular structures in canine circumanal gland carcinoma cells.

Intranuclear cisternal and vesicular structures, bound by a single membrane, were observed for the first time in some glandular "bird's eye" cells of canine circummanal gland carcinomas. The role of these intranuclear structures is not clear. It is suggested that they may be involved in cellular adaptation to an environment of nutrient deficiency, as a result of cell overcrowding.

Clinicopathological manifestations of selected neoplasms.

This report provides a general overview of the pathobiology of neoplasia, and an update on the clinicopathological manifestations of lymphosarcoma, mastocytoma, histiocytoma, melanoma, sarcoid and circumanal gland tumors in domestic animals. Neoplasia represents a continuum of events from reversible hyperplasia to irreversible and pathological changes in tissue growth patterns. In some instances the causes of this disease process have been identified, but the etiology of the majority of naturally occurring neoplasms remain unknown. Surgical excision is the preferred treatment for tumors, but is often more beneficial when combined with chemotherapy, radiotherapy or immunotherapy. The successful diagnosis and management of neoplastic disease in domestic animals necessitates a thorough awareness of the clinical presentation and biologic behavior of specific tumors on the part of veterinarians who provide health care for these species.

Hormone-dependent neoplasms of the canine perianal gland.

The epidemiological features of 472 dogs with microscopically confirmed neoplasms of the perianal gland are described. These general characteristics suggest etiological factors similar to those responsible for hormone-related neoplasms occurring in human beings. Perianal gland tumors appear to be androgen dependent. Male dogs show a 5.6-fold-increased risk compared with females; endogenous estrogens offer protection and the use of estrogenic hormones is conventional therapy for the benign lesion. Both sexes of the cocker spaniel breed show excessively high risk, suggesting that this dog family may be a model for genetic studies that could be relevant to familial aggregations of hormone-related tumors in men and women. Adrenocortical hormones may play a role in the development of the tumor in female dogs. Research into alterations of the biochemical pathways of steroidogenesis in affected female dogs may provide clues to similar conditions in humans.

A malignant neoplasm resembling a circumanal gland adenocarcinoma in a dog.

In the neoplasm of this report a final diagnosis of a circumanal gland adenocarcinoma invading the vertebral column and canal was made based on the histologic appearance. No growths were noted in the circumanal gland region and the location of the primary neoplasm is open to debate.

Tissue-steroid interactions in canine hormone-dependent tumours.

Mammary tumour tissue from two bitches and an anal adenoma from a dog were investigated for steroid receptor interaction. Both mammary tumours possessed cytoplasmic macromolecules sedimenting with coefficients of 4S and 8S that bound oestradiol-17beta. These receptors had molecular weights of approximately 60,000 and 180,000 respectively. Transfer of the oestrogen to the nucleus was shown and the presence of a 4-5S nuclear protein demonstrated. The anal adenoma had a cytoplasmic receptor, with a sedimentation value in a sucrose density gradient of 4-5S with respect to bovine serum albumin, that bound tritiated 5alpha-androstane-3alpha, 17alpha-diol. No affinity could be demonstrated for other C19-steroids examined. The significance of these findings in terms of the hormone dependence of the tumours investigated and the possible development of these studies to promote rational therapy in such cases is discussed.

Perianal adenoma of apocrine origin in a dog.

At necropsy, a 15-year-old male Standard Poodle had a 6-cm diameter mass in the perianal region. Histologic examination revealed an adenoma of apocrine tubular gland origin, rather than the more common type of perianal gland adenoma derived from modified sebaceous glands. The diameter of the mass had increased from 3 to 6 cm in 12 months and it had failed to respond to treatment with repository stilbestrol.