Immunohistochemical detection of thyroid transcription factor-1, thyroglobulin, and calcitonin in canine normal, hyperplastic, and neoplastic thyroid gland.

Immunohistochemistry for thyroid transcription factor-1 (TTF-1), thyroglobulin, and calcitonin was done in normal, hyperplastic, and neoplastic canine thyroid glands that had been fixed in formalin and embedded in paraffin. Prolonged fixation did not significantly alter the immunostaining for TTF-1. Staining for TTF-1 was always nuclear and usually strong. One of two C-cell adenomas, five of five follicular cell adenomas, 5 of 11 C-cell carcinomas, 38 of 42 follicular cell carcinomas, two of five cases of C-cell hyperplasia, two of two cases of follicular epithelial hyperplasia, one of two metastatic C-cell carcinomas, and three of four metastatic follicular carcinomas were positive for TTF-1. One follicular carcinoma that was positive for TTF-1 was negative for thyroglobulin. Thirty-nine of 42 follicular cell carcinomas were positive for thyroglobulin, including two cases that were negative for TTF-1. All C-cell lesions were positive for calcitonin. Of a variety of normal canine tissues and 278 nonthyroid tumors, only normal lung (airway and alveolar epithelial cells) and four of five pulmonary carcinomas were positive for TTF-1. TTF-1 is a good marker of thyroid differentiation and can be used in conjunction with thyroglobulin and calcitonin to increase the detection and differentiation of thyroid tumors and their metastases.

Immunoreactivity of A103, an antibody to Melan A, in canine steroid-producing tissues and their tumors.

The monoclonal antibody A103 to the melanocytic differentiation antigen Melan A stains human steroid-producing cells and their tumors. A total of 200 formalin-fixed, paraffin-embedded canine normal tissues and hyperplastic and neoplastic lesions of the adrenal gland, testis, and ovary were immunohistochemically tested for Melan A with antibody A103. Leydig cell tumors (23/23, 100%), Sertoli cell tumors (14/15, 93%), and adrenocortical adenomas (12/13, 92%) were consistently positive. Adrenocortical carcinomas (23/35, 65%) and granulosa cell tumors (10/17, 59%) were less frequently positive. All pheochromocytomas, seminomas, and dysgerminomas were negative. The pattern of staining was cytoplasmic, but nuclear staining was also frequently seen in normal Leydig cells and their tumors. As in human tumors, immunohistochemistry for Melan A stains many canine steroid-producing tumors and can be used to distinguish these tumors from those of nonstereidogenic cells.

Mammary duct ectasia in dogs: 51 cases (1992-1999).

OBJECTIVE: To evaluate the clinical and pathologic characteristics of mammary duct ectasia in dogs. DESIGN: Retrospective study. ANIMALS: 51 dogs with mammary duct ectasia. PROCEDURE: Information regarding body condition, history, number and location of affected mammary glands, appearance of lesions, surgical treatment, nonsurgical treatment, and evidence of recurrence or development of mammary neoplasia was obtained from surveys sent to referring veterinarians. Results of information from examination of histologic sections and referring veterinarians were evaluated for all mammary duct ectasia biopsies performed between 1992 and 1999. RESULTS: Duct ectasia was the primary diagnosis in 51 of 1,825 (2.8%) mammary biopsy specimens and comprised 48% of nonneoplastic mammary diseases. Affected dogs were evenly distributed over a range of 1 to 13 years of age, with a mean age at the time of diagnosis of 6.1 +/- 3.1 years. All dogs were female (31 sexually intact, 20 spayed); 10 of 26 had whelped. Duct ectasia was described as nodular (26 dogs), cystic (13), and multiglandular (11) and located in caudal (31) more often than cranial (14) or middle glands (10). Ectasia recurred in 3 dogs. One dog had a history of previously excised mammary adenocarcinoma; another subsequently developed mammary carcinoma. CONCLUSIONS AND CLINICAL RELEVANCE: Duct ectasia affected mature, sexually intact and spayed female dogs over a wide age range. Certain breeds were affected more commonly than expected. Increased risk for mammary neoplasia was not evident. Duct ectasia should be considered as a cause for mammary enlargement, especially in young dogs or when its cystic nature is evident. Mastectomy is usually curative, and neoplasia should be ruled out in dogs with ectasia.

Retrospective study of 338 canine oral melanomas with clinical, histologic, and immunohistochemical review of 129 cases.

Diagnostic records from 338 canine oral melanomas in 338 dogs received at the Veterinary Medical Diagnostic Laboratory (1992-1999) were reviewed. Of these tumors, 122 plus an additional 7 metastatic melanomas of unknown origin were selected for clinical follow-up, histologic review, and immunohistochemistry. Chow Chow, Golden Retriever, and Pekingese/Poodle mix breeds were overrepresented, whereas Boxer and German Shepherd breeds were underrepresented. There was no gender predisposition and the average age at presentation was 11.4 years. Forty-nine dogs were euthanized due to recurrence or metastasis. The average postsurgical survival time was 173 days. The gingiva and the labial mucosa were the most common sites. Most tumors were composed of either polygonal cells (27 cases, 20.9%), spindle cells (44 cases, 34.1%), or a mixture of the two (polygonal and spindle) (54 cases, 41.9%). Clear cell (3 cases, 2.3%) and adenoid/papillary (1 case, 0.8%) patterns were uncommon. The metastases of 6/6 oral melanomas had morphologic and immunohistochemical features similar to those of the primary tumors. Immunohistochemically, Melan A was detected in 113/122 oral (92.6%) and 5/7 (71.9%) metastatic melanomas. Only 4/163 nonmelanocytic tumors were focally and weakly positive for Melan A. Antibodies against vimentin, S100 protein, and neuron-specific enolase stained 129 (100%), 98 (76%), and 115 (89.1%) of 129 melanomas, respectively. Antibodies against other melanocytic-associated antigens (tyrosinase, glycoprotein 100) did not yield adequate staining. We conclude that Melan A is a specific and sensitive marker for canine melanomas.

Intestinal multinodular A lambda-amyloid deposition associated with extramedullary plasmacytoma in three dogs: clinicopathological and immunohistochemical studies.

Intestinal extramedullary plasmacytomas (EMPs) are rare tumours in dogs. Three cases of canine intestinal EMP with amyloid deposits are described in this report. These tumours, which were located in the rectal submucosa, had variable numbers of well-differentiated plasma cells and fewer multinucleated giant cells of plasmacytoid and histiocytic morphology, admixed with abundant amyloid. Two cases had metaplastic cartilage and bone within the amyloid deposits. Immunohistochemically, the plasma cells of all three tumours reacted for lambda-light chains of immunoglobulins but not for kappa-chains, indicating monoclonality. Plasma cells of two tumours were also positive to CD79a antiserum. Amyloid deposits were labelled with an A lambda (amyloid of immunoglobulin lambda-light chain origin) antiserum but not with antisera against its precursor protein, the immunoglobulin lambda-light chains, indicating possible conformational changes of amyloidogenic proteins during their transformation into amyloid.

Complications of balloon catheterization associated with aberrant cerebral arterial anatomy in a horse with guttural pouch mycosis.

A 3-year-old Quarter Horse gelding was treated for left guttural pouch mycosis by ligation and balloon catheterization of the left internal carotid artery. Catheter advancement was shorter (10 cm) than the normally reported distance (13-15 cm), but was observed endoscopically during placement as it coursed within the internal carotid artery through the guttural pouch. The horse developed a persistently abnormal respiratory pattern after catheter placement, failed to gain consciousness, developed pulmonary edema, and died 5.5 hours postoperatively. Postmortem examination revealed an aberrant left internal carotid arterial course with location of the embolectomy catheter at the junction of the basilar and caudal cerebellar arteries. Brainstem neuronal necrosis and alveolar and interstitial pulmonary edema were identified on histological examination. Angiography may be used to identify aberrant branching patterns. Failure to identify and occlude aberrant branches may result in fatal epistaxis and Brainstem lesions.

Intestinal extramedullary plasmacytoma associated with amyloid deposition in three dogs: an ultrastructural and immunoelectron microscopic study.

Samples from rectal plasmacytoma in three adult dogs that were diagnosed by light microscopy and immunohistochemistry were examined by electron microscopy. The most common cell type had typical plasmacytoid features. A second cell type was a plasmacytoid giant cell with single or multiple eccentric nuclei, irregular nuclear membrane, abundant and dilated rough endoplasmic reticulum, and numerous electron-dense granules. The third cell type was a histiocytic giant cell that intermingled with plasmacytoid cells. All three tumors had abundant amyloid, mainly in the interstitium but also within histiocytic cells and less commonly in plasma cells or plasmacytoid giant cells. Extracellular and intracellular amyloid fibrils and the contents of membrane-bound electron-dense bodies of plasma cells reacted with antibody to lambda-light chain of immunoglobulins by immunogold staining.

Acute arsenic toxicosis in five horses.

Five adult horses presented with acute clinical signs of watery diarrhea, excessive salivation, muscle tremors, ataxia, and depression. Four died within 24 hours and the fifth was euthanatized approximately 48 hours after onset of clinical signs. Necropsy finds in two of the horses included hyperemia of gastric mucosa, intestines filled with green to black watery fluid, and multifocal to coalescing, hemorrhagic 1.0-2.0-cm-diameter ulcers of the mucosa of the cecum and large colon. Histopathologic changes in the cecum and large colon consisted of mucosal necrosis and ulceration, vascular thrombosis, necrosis of submucosal blood vessels, and infiltration by mixed mononuclear inflammatory cells and neutrophils. Arsenic toxicosis was suspected. The owner had not been feeding the horses any grain; however, a mixture of grain and pink powder was found in the pasture. Liver arsenic concentrations in the two horses were 14.0 and 11.0 ppm, a sample of renal cortex contained 108 ppm arsenic, and the grain/powder mixture found in the pasture was positive for arsenic at > 3,000 ppm. kidney lead concentrations were 6.5 and 4.2 ppm. Results were consistent with lead arsenate or lead arsenite poisoning.

Comparison of the degree of abdominal adhesion formation associated with chromic catgut and polypropylene suture materials.

OBJECTIVE: To evaluate the histologic pattern and biomechanical properties of adhesions caused by chromic catgut and polypropylene sutures, using an enteropexy model. DESIGN: Enteropexies were created in dogs, using chromic catgut and polypropylene suture. The adhesions associated with the enteropexies were examined histologically and mechanically. ANIMALS: 6 mixed-breed dogs weighing 16 to 20 kg. PROCEDURE: 72 enteropexies were created between the jejunum and abdominal wall. 36 sites were sutured with chromic catgut and 36 were sutured with polypropylene. 3 dogs were euthanatized after 1 week. The remaining dogs were euthanatized after 1 month. Samples of the enteropexy sites were obtained for histologic examination. The remaining sites were mechanically distracted until failure of the enteropexy site or adjacent tissue occurred. RESULTS: Histologic examination of the enteropexy sites did not reveal substantial differences in the degree of inflammation between the 2 suture types at 1 week or 1 month. The degree of inflammation decreased and the maturity of fibrous tissue formed at the enteropexy sites increased for all specimens over time. No statistically significant difference in breaking strength was observed between suture types at 1 week or 1 month. CONCLUSION: In dogs, the formation and strength of intentionally created abdominal adhesions are not increased by use of chromic catgut. CLINICAL RELEVANCE: Selection of chromic catgut suture for use in surgical procedures where adhesions are desired is unwarranted.

Effects of dietary supplementation with fructooligosaccharides on colonic microbiota populations and epithelial cell proliferation in neonatal pigs.

Two experiments were conducted with neonatal pigs to determine the effects of feeding fructooligosaccharides on cecal and colonic microbiota, proliferation of cecal and colonic epithelial mucosa, and short-chain fatty acid concentrations in the cecum. Experiment 1 consisted of feeding neonatal pigs diets containing either 0 or 3 g fructooligosaccharies/L of formula for 15 days and then examining the large intestine for changes in cecal and proximal colonic microbiota; cecal pH; short-chain fatty acid concentrations; morphology of cecal, proximal, and distal colonic epithelial mucosa; gross necropsy; and histopathology. Supplementation with fructooligosacchariudes (FOS) did not alter cell counts of viable bifidobacterial organisms or total anaerobic microbiota, cecal pH, or concentrations of short-chain fatty acids. Cecal mucosal cell density and labeled cells increased with FOS consumption. Proximal colonic mucosal crypt height, leading edge, labeled cells, proliferation zone, and labeling index increased with FOS consumption. Distal colonic mucosal crypt height, leading edge, cell density, labeling index, and labeled cells increased with FOS consumption. Gross necropsy and histopathology found no significan lesions. In Experiment 2, neonatal pigs were fed diets containing either 0 or 3 g fructooligosaccharides/L of formula for 6 days. Fecal samples were collected on the first full day of feeding and on days 3 and 6 after initiation of feeding. On days 1 and 3, concentrations of bifidobacteria were similar between diets; however, on day 6, pigs consuming FOS tended to have greater numbers of bifidobacteria (p = 0.08). These data suggest dietary consumption of FOS will enhance bifidobacteria populations and prevent colonic epithelial mucosa atrophy in neonates fed an elemental diet.

Disseminated peritoneal leiomyomatosis in a horse.

A 6-year-old female Quarter Horse became inappetent, lost weight, was febrile, and had abdominal enlargement and infrequent bouts of mild colic. Palpation per rectum detected a prominent, smooth-walled mass adjacent to the pelvic flexure of the colon. Analyses revealed the peritoneal fluid was apparently normal except for a high protein concentration. By the use of ultrasonography, the mass was observed adjacent to the body wall in many locations throughout the abdomen, appearing as an irregular, multiloculated structure composed of innumerable cysts of various sizes with interspersed, circular hyperechoic nodules. A celiotomy was performed, and the 34-kg mass was removed. On the basis of histologic examination, a diagnosis of disseminated peritoneal leiomyomatosis was made. The horse had an uncomplicated recovery and gained weight. Further problems have not been reported and the horse subsequently gave birth to a healthy foal. A complete examination of the horse 22 months after surgery did not reveal signs of redevelopment of the condition.

Induction of acute bronchopneumonia in mice by intrabronchial inoculation of Pasteurella haemolytica serotype 1.

Dose dependent pulmonary lesions of acute bronchopneumonia were induced in male, outbred Swiss Webster mice by intrabronchial inoculation of Pasteurella haemolytica. Five exponential dilutions ranging from 5 x 10(4) to 5 x 10(8) colony forming units per mL (CFU/mL) of Pasteurella haemolytica serotype 1 were inoculated into five groups of mice. Mice were killed by cervical dislocation 24 hours postinoculation. Pulmonary lesions occurred in mice of all five groups, however, 5 x 10(7) CFU/mL was the minimal dose which consistently produced lesions. Focal parenchymal necrosis, suppurative bronchiolitis, and flooding of interalveolar septa and alveoli by edema fluid, fibrin, neutrophils and macrophages, were observed microscopically. We conclude that outbred Swiss Webster mice can be used as a model for the study of selected disease mechanisms of acute lung inflammation and that this model may be used to determine some of the pathogenic mechanisms involved in the development of pulmonary lesions in bovine pneumonic pasteurellosis.

Immunohistochemical staining of feline malignant fibrous histiocytomas.

Malignant fibrous histiocytoma was diagnosed in seven cats from biopsy specimens received at the University of Missouri Veterinary Medical Diagnostic Laboratory during a 4-year period from 1987-1991. Tissue blocks from formalin-fixed specimens were resectioned and stained for type I (AE1) and type II (AE3) cytokeratins, desmin, S100 protein, vimentin, and alpha 1-antitrypsin by the avidin biotin peroxidase complex method with diaminobenzidine (DAB) chromogen. None of the tumors stained positively for alpha 1-antitrypsin. Four of seven of the tumors had similar immunohistochemical staining results, with positive staining for type I and type II cytokeratins, desmin, S100 protein, and vimentin. Of the remaining three, one stained positively only for S100 protein and vimentin; one stained positively for vimentin only; and one was negative for all six antigens. Based only on immunohistochemical staining results, three of the tumors could possibly be reclassified: one as a melanoma, one as a probable fibrosarcoma, and one as unknown. These results also indicate that feline malignant fibrous histiocytomas show a diversity of intermediate filament expression, as do human tumors. Our results also do not support the theory that malignant fibrous histiocytomas are of histiocytic origin.

Marking margins of tumorectomies and excisional biopsies to facilitate histological assessment of excision completeness.

Assessment of tumor margins for completeness of excision is important for local control of neoplastic masses, particularly those that are potentially curable with surgery. Of the margin-marking techniques available, India inking seems to be the most practical way for veterinary clinicians to help pathologists accurately distinguish between surgical margins and margins created during sample processing. India inking prevents misinterpretation of contaminated processing margins as inadequate surgical excisions; however, a strongly definitive decision that an excision is complete cannot be made with any margin-marking technique because it is impossible to examine the entire surface of every margin.