A Brief Review of Infrequent Spontaneous Findings, Peculiar Anatomical Microscopic Features, and Potential Artifacts in Göttingen Minipigs.

Minipigs are now used in greater numbers in contract research organizations (CROs) as well as in the pharmaceutical industry. Most CROs or pharmaceutical companies use the Göttingen minipig, which displays a number of important background lesions. This review will discuss some of the more infrequent minipig background changes. Porcine stress syndrome is an autosomal recessive pharmacogenetic disorder in minipigs causing malignant hyperthermia and muscle necrosis. Possible triggers, clinical pathology as well as heart, muscle, liver, lung, and kidney histopathology are discussed. Additional spontaneous changes, background findings, and peculiar anatomical and histological features include thrombocytopenic purpura syndrome, spontaneous glomerulonephritis, osteochondritis, ellipsoids, or Schweigger-Seidel sheaths in the spleen, as well as the presence of a perimesenteric plexus adjacent to mesenteric lymph nodes, squamous epithelial metaplasia of the salivary gland, and cupping of the optic disk in the minipig eye. In order to maximize the data gained from minipig studies, the interpretation of pathology findings requires the input of experienced pathologists who understand the significance of artifacts and spontaneous, background lesions in minipigs and can distinguish these from induced lesions.

E-cadherin expression in canine cutaneous histiocytomas.

Canine cutaneous histiocytoma is a common skin tumour of Langerhans cell origin. Langerhans cells are members of the dendritic cell family of antigen-presenting cells and are located in the epidermis. They are unique among the dendritic cell lineage in that they express high levels of the adhesion molecule E-cadherin. The expression of E-cadherin by the neoplastic Langerhans cells in 37 dogs with cutaneous histiocytoma was studied by flow cytometry and immunohistochemistry. In all the cases, these cells expressed E-cadherin, whereas the infiltrating lymphocytes did not.

Caecal impaction and chronic intestinal pseudo-obstruction in a dog.

A 10-year-old female neutered cross-breed dog presented with a 4-month history of chronic intermittent diarrhoea and vomiting. Abdominal ultrasound showed dilated loops of small intestine and a suspected faecolith. Exploratory surgery revealed a caecal impaction and a typhlectomy was performed. Histopathological examination of caecal and full thickness small intestine sections demonstrated atrophy of smooth muscle fibres as well as an influx of plasma cells, lymphocytes and macrophages, and mild lymphoplasmacytic and eosinophilic enteritis. This combination of caecal impaction and chronic intestinal pseudo-obstruction has not been reported previously in the dog.

Immunohistochemical and histopathologic features of 14 malignant fibrous histiocytomas from Flat-Coated Retrievers.

Flat-Coated Retrievers seem to be at increased risk of developing soft-tissue sarcomas, and undifferentiated round cell or spindle cell sarcomas account for approximately 59% of sarcomas in the breed. In an attempt to classify these tumors further, formalin-fixed, paraffin-embedded sections from 14 undifferentiated sarcomas from Flat-Coated Retrievers were reviewed and examined with a panel of histologic and immunohistochemical stains. The panel included vimentin, desmin, Myo D1, smooth muscle actin, cytokeratin, S100, von Willebrand factor (factor VIII), Mac 387, CD3, major histocompatibility complex (MHC) class II, and CD79a. The majority of the sarcomas showed greater than 70% staining for MHC class II. We conclude that these undifferentiated sarcomas in Flat-Coated Retrievers belong to a spectrum of tumors with varying proportions of characteristic cell types and morphologic features, some of which fit the diagnostic criteria for malignant fibrous histiocytoma. Many of these sarcomas seem to have a significant myofibroblast component and a mild or moderate T cell infiltrate but the precise cell lineage is still uncertain.

Prognostic variables in canine multicentric lymphosarcoma.

This paper presents the results of a prospective study to investigate the prognostic value of clinical staging, histological grading, immunophenotype, mitotic count and average numbers of argyrophilic nucleolar organiser region counts in dogs with multicentric lymphosarcoma treated with a standard chemotherapy protocol comprising vincristine, cyclophosphamide and prednisolone. Forty-nine dogs were treated according to the study protocol. Univariate and multivariate analysis with regression modelling was used to evaluate the prognostic importance of patient and tumour variables upon tumour response and relapse-free survival. Thirty-seven dogs (76 per cent) achieved a complete remission, seven (14 per cent) a partial remission and five (10 per cent) failed to respond to treatment. None of the variables examined had a statistically significant effect upon tumour response. Tumour immunophenotype was the only parameter found to have a significant influence on patient survival, the hazard ratio for T-cell versus B-cell immunophenotype was 3.99 with 95 per cent confidence interval from 1.399 to 11.372, P = 0.035.

Histopathological survey of neoplasms in flat-coated retrievers, 1990 to 1998.

Over the period from March 1990 to December 1998, veterinary surgeons in general practice were invited to submit tissues suspected of being neoplastic which had been removed from flat-coated retrievers. When possible, pedigree details were obtained from the owners. In addition, data were collected from flat-coated retrievers known to have suffered from a neoplastic condition and for which a histopathological report was available. A total of 1023 submissions was obtained from 782 dogs. These included 165 non-neoplastic lesions (16 per cent), 447 benign samples (44 per cent) and 411 malignant samples (40 per cent). Soft tissue sarcomas accounted for 55 per cent of the malignant samples (26 per cent of all tumour samples and 22 per cent of all submissions) with 63 per cent of them being diagnosed as undifferentiated. Carcinomas accounted for 20 per cent of malignant samples (8 per cent of all submissions). Of the benign tumours, cutaneous histiocytoma was the most common diagnosis (48 per cent of benign tumours, 25 per cent of all tumours and 21 per cent of all submissions).

Possible vaccine-induced canine distemper in a South American bush dog (Speothos venaticus).

Suspected vaccine-induced canine distemper was diagnosed in a captive female bush dog (Speothos venaticus). Macroscopic lesions included mild congestion of the gastric mucosa and focal consolidation of the lung. Histopathological lesions included status spongiosis, gliosis, widespread eosinophilic, intranuclear and intracytoplasmic inclusion bodies in neurons, astrocytes and gitter cells of the cerebral, cerebellar and spinal white matter.