Immunocytochemical study of tissues from clinically normal dogs and of neoplasms, using keratin monoclonal antibodies.

Three commonly used keratin monoclonal antibodies (MAB)--AE1:AE3, CAM 5.2, and MAK-6--were compared with routinely used cytokeratin antibody. The expression of these antibodies was analyzed in several tissues obtained from clinically normal dogs and in a variety of neoplasms from dogs. Using appropriate enzymatic digestion, paraffin-embedded tissues processed in routine manner retained their typical keratin expression. Differentiated and poorly differentiated epithelial neoplasms, lymphomas, and melanomas were studied by use of the avidin-biotin-peroxidase technique. All 4 of the aforementioned antibodies had similar staining profiles. Of 3 anaplastic carcinomas, 2 had positive reaction to all 4 antibodies. All lymphomas, plasma cell tumors, and amelanotic melanomas had negative reaction to MAK-6, CAM 5.2, AE1:AE3, and cytokeratin MAB. Three basal cell epitheliomas had positive reaction to all 4 antibodies, whereas 1 basal cell tumor with a solid pattern had negative staining reaction. Two carcinoids had negative reaction to all markers and 1 of 2 malignant chemodectomas and 1 transitional cell carcinoma had staining reaction to only AE1:AE3 MAB. Comparing the 4 antibodies, use of AE1:AE3 MAB produced the strongest staining intensity followed by cytokeratin, MAK-6, and CAM 5.2 MAB. All 4 antibodies had low background staining. In conclusion, AE1:AE3 and MAK-6 MAB are as useful as cytokeratin MAB for identification of poorly differentiated epithelial neoplasms in dogs and cats.     

Application of the peroxidase-antiperoxidase procedure to the localization of pituitary hormones and calcitonin in various domestic animals and human beings

Specific cell populations in the pituitary glands of the rat, cat, pig, and human being were positive for thyroid-stimulating hormone (TSH), luteinizing hormone (LH), and follicle-stimulating hormone (FSH). When reacted with prediluted rabbit anti-human TSH, LH, and FSH, antisera were not positive for the demonstration of these hormones in the horse, cow, or dog. Immunocytochemical staining was obtained in the horse, cow, and dog by the use of a primary antiserum against a specific beta-subunit of bovine TSH. The immunocytochemical staining of TSH, LH, FSH, adrenocorticotropic hormone, growth hormone, prolactin, and calcitonin was examined by the peroxidase-antiperoxidase method, using standard commercially available kits. All species examined had a strong positive reaction in specific pituitary cell populations for adrenocorticotropic hormone, growth hormone, and prolactin. Sections of normal thyroid gland tissue had positive staining of C cells containing calcitonin at the dilution of 1:100 of the primary antibody in the rat, horse, cow, dog, cat, pig, and human being.     

Scanning electron microscopy of the canine atrioventricular bundle and moderator band

The atrioventricular (AV) bundle and the moderator band in the canine heart were examined by scanning electron microscopy. The AV bundle and the moderator band both were comprised of large, cylindrically shaped cells. These cells were highly organized into bundles, with minimal lateral communication between bundles. There was extensive cell-to-cell communication between cells within a bundle. The end branching of individual cells was prominent, with some interbundle communication. These results are discussed in relationship to the electrophysiologic properties of the AV bundle and the conduction velocity.     

Congestive cardiomyopathy in a dog associated with pregnancy

A two-year-old, six-week postpartum female dog was presented with acute congestive heart failure for treatment. The patient collapsed and suddenly died. Postmortem examination revealed an enlarged, dilated heart with thin ventricular walls. Histologically, scattered multifocal areas of myocardial degeneration and necrosis with fibrosis were seen in the myocardium. This case of acute cardiomyopathy in a female dog six weeks postpartum is similar to the well-described, postpartum cardiomyopathy in man. The etiology of this case was not ascertained.     

Diagnostic immunohistochemistry of canine round cell tumors

Sixty-five canine skin neoplasms studied using immunocytochemistry, included 22 histiocytomas, 18 amelanotic melanomas, 14 cutaneous lymphosarcomas, six mast cell tumors, and five transmissible venereal tumors. Formalin-fixed, paraffin-embedded sections were stained using the avidin-biotin-peroxidase complex (ABC) immunoperoxidase technique for reactivity with S-100 protein, kappa and lambda immunoglobulin light chains, alpha-1-antitrypsin, alpha-1-antichymotrypsin, leukocyte common antigen (LCA), neuron-specific enolase, keratin, cytokeratin, muramidase, and vimentin. Detection of S-100, kappa and lambda light chains, neuron-specific enolase, and vimentin were most useful for screening these neoplasms. None of the markers examined was consistent in staining histiocytomas. While reactivity of S-100 (ten cases) and neuron-specific enolase (ten cases) was detected in some amelanotic melanomas, lambda light chain immunoglobulin (eight cases) was relatively consistent in cutaneous lymphomas. Mast cell neoplasms reacted with avidin and, therefore, were positive, even on negative control sections. Vimentin reacted strongly on all amelanotic melanomas and transmissible venereal tumors examined. These antibodies are helpful adjuncts in the differential diagnosis of canine skin tumors.     

Histological and ultrastructural evaluation of cardiac lesions in idiopathic cardiomyopathy in dogs.

Described are pathological studies of eight dogs which died in congestive heart failure, with a clinical diagnosis of congestive cardiomyopathy. Examination revealed marked dilatation and enlargement of all four chambers of the heart. The ventricular walls were thin with small atrophic papillary muscles. Histological studies on the myocardium revealed scattered areas of myocardial necrosis, especially around the papillary muscles of the left ventricle and random scattered areas of fibrosis. Electron microscopic studies revealed fewer and disoriented myofibrils, myocytolysis, increased numbers of mitochondria with swelling and inclusions, increased glycogen granules and increased numbers of lysosomes, lipofuscin granules and lipid droplets. Mild Z-band abnormalities were found throughout the myofibers.     

Immunohistochemical staining for S100 protein in the diagnosis of canine amelanotic melanoma

Formalin-fixed, paraffin-embedded tissue samples of canine amelanotic melanomas and normal canine tissues were studied immunohistochemically for the presence of S100 protein. Use of the avidin-biotin complex procedure demonstrated variable amounts of S100 protein in the tumor cell cytoplasm and nuclei in 26 of 31 tumors. S100 protein was not observed in some other common canine skin tumors stained by the avidin-biotin complex technique. These were a mast cell tumor, fibrosarcoma, mammary gland adenocarcinoma, histiocytoma, transmissible venereal tumor, and a thyroid gland adenocarcinoma. Among normal tissues the presence of S100 protein was demonstrated in chondrocytes in the trachea, myoepithelial cells in the breast, melanocytes in the skin, some sweat glands and ducts in the skin, stellate cells in the pituitary, and interdigitating reticulum cells in the lymph node and in Peyer's patches. These results indicate that the avidin-biotin complex procedure for demonstrating S100 protein is a useful diagnostic tool in the diagnosis of canine amelanotic melanoma.