Fibroblastic Subtype has a Favourable Prognosis in Appendicular Osteosarcoma of Dogs.

Osteosarcoma (OS) is an aggressive malignant bone neoplasm that occurs mostly in the appendicular skeleton of dogs and people. OS is classified based on the presence of malignant stroma and the formation of extracellular matrix into osteoblastic, chondroblastic and fibroblastic forms. This study investigated the correlation between the three histological subtypes of canine OS and clinical outcome. Additionally, we examined whether there was any difference in the immunolabelling of desmin, S100 and neuron-specific enolase (NSE) between the three histological subtypes. Formalin-fixed and paraffin wax-embedded tissues from 87 dogs with primary OS were available for this study. The survival times were correlated with appendicular OS subtypes in dogs that were treated surgically, received adjuvant chemotherapy and had no pulmonary metastasis at the time of diagnosis. Dogs with an appendicular fibroblastic OS had significantly prolonged mean average survival times (546 ± 105 days) in comparison with dogs having appendicular osteoblastic (257 ± 48 days) or appendicular chondroblastic (170 ± 28 days) OS (P = 0.003, Log Rank). The results also revealed that the appendicular chondroblastic subtype is a significant indicator for poor prognosis in dogs compared with the fibroblastic or osteoblastic subtypes (P = 0.006, Cox regression). Moreover, the findings indicated that there was no significant correlation between the localization of desmin, NSE or S100 and histological subtypes. Importantly, dogs with appendicular fibroblastic OS were found to have a better prognosis when compared with dogs with other subtypes. This may suggest that histological subtypes of appendicular OS have diverse behaviour and could be used to categorize patients for risk-based assessment.

Canine Mixed Mammary Tumour as a Model for Human Breast Cancer with Osseous Metaplasia.

Canine mixed mammary tumours (CMMTs) and human metaplastic breast carcinomas (HMBCs) share several histopathological features and risk factors. In both species, these tumours display epithelial and stromal components. HMBCs are rare malignant tumours, but CMMTs are one of the most common mammary tumours in dogs and are more often benign than malignant. In this study, benign (n = 88) and malignant (n = 13) CMMTs were characterized using specific antibodies against oestrogen receptor, progesterone receptor, human epidermal growth factor receptor 2, cytokeratin 5/6, cytokeratin AE1/AE3, vimentin, Ki67, E-cadherin and p63. Cartilage and bone matrices associated with benign and malignant CMMTs were characterized using specific antibodies against BMP4, Runx2, Sox9 and osteopontin. The current study suggested that CMMTs are of epithelial origin, but display a myoepithelial-like differentiation. The findings suggest key roles for Sox9, Runx2 and BMP4 in chondrogenesis and bone formation in CMMTs. The high expression of osteopontin in CMMTs appears to be unrelated to tumour malignancy.

Lythrum hyssopifolia (lesser loosestrife) poisoning of sheep in Victoria.

OBJECTIVE: To document an ovine disease attributed to the consumption of Lythrum hyssopifolia (lesser loosestrife). PROCEDURES: Historical and histological review of field and experimental cases. RESULTS: 1-20% mortality occurred in sheep flocks grazing paddocks where L. hyssopifolia was the predominant green vegetation. Well-documented disease outbreaks occurred in summer on nine farms across Victoria between 1974 and 2002. Liver damage occurred in all nine outbreaks, with kidney damage in at least eight. Hepatocyte necrosis was usually zonal to midzonal (zone 2) in the liver samples from four farms and periacinar (zone 3) in those from three farms, but some livers showed only single-cell necrosis. Multinucleate hepatocytes near necrotic areas were a feature in six cases. Proximal tubular epithelium appeared to be the primary renal target and brown granules were often present in renal tubules. Biochemical and histological evidence of liver and kidney damage was obtained from two sheep experimentally pen-fed harvested L. hyssopifolia. CONCLUSION: Chemicals in L. hyssopifolia are toxic to ovine hepatocytes and renal tubular epithelial cells.

Fatal encephalitozoonosis in two koalas.

Two young koalas from a fauna park, recently out of the pouch and approximately 6 months old, were found dead with no previous clinical signs or gross lesions. On histopathological examination, large numbers of spores consistent with a microsporidian organism were present intracellularly within the small intestinal mucosa. Electron microscopy and polymerase chain reaction studies (sequencing the 5' end of the SSU RNA gene) identified the organism as Encephalitozoon intestinalis with 100% homology with those of previously reported human isolates. This is believed to be the first report of this organism in a marsupial.

Case report: six cases of verminous pneumonia (Muellerius sp.) in goats.

Six cases of verminous pneumonia in goats due to Muellerius sp. were reviewed. In only one case was the pneumonia diagnosed antemortem. The gross necropsy findings and histopathology revealed a widespread interstitial pneumonia in all the cases. There was variability in the local reaction around the parasites from almost none in the mildest cases to larger focal accumulations of macrophages and mononuclear inflammatory cells. Only in the severest cases were eosinophils seen and even then were scattered and few in number. No nodular lesions were seen associated with the parasites. The pathology of the pulmonary lesions in goats appears to be more commonly of the diffuse type and therefore significantly different from the nodular lesion usually observed in sheep.