Imaging and score-based quantification of ovine pulmonary adenocarcinoma using computed tomography as an additional tool in advanced clinical diagnosis

Selenium, copper and iron in veterinary medicine-From clinical implications to scientific models

Diseases related to copper, selenium or iron overload or deficiency are common and well-described in large animal veterinary medicine. Some of them certainly have the potential to serve as useful animal models for ongoing research in the field of trace elements. Obvious advantages of large animal models compared to laboratory animal models like rats and mice are the option of long-term, consecutive examinations of progressive deficient or toxic stages and the opportunity to collect various, high volume samples for repeated measurements. Nevertheless, close cooperation between scientific disciplines is necessary as scientists using high sophisticated analytical methods and equipment are not regularly in touch with scientists working with large animal diseases. This review will give an introduction into some typical animal diseases related to trace elements and will present approaches where the animal diseases were used already as a model for interdisciplinary research.

Assessment of transthoracic ultrasound diagnosis of ovine pulmonary adenocarcinoma in adult sheep

Ovine pulmonary adenocarcinoma (OPA), caused by Jaagsiekte sheep retrovirus (JSRV), is a disease of increasing concern in the sheep industry. There is no commercial antemortem test for OPA; therefore, an early evaluation phase study was undertaken to examine the accuracy of transthoracic ultrasound examination using a 5-6.5 MHz sector ultrasound machine widely available in veterinary practice in the UK to diagnose OPA. Restraint, preparation and examination time was restricted to five minutes per sheep to represent the cost limitations of commercial sheep farming. One hundred sheep were examined. All 41 cases identified with suspect OPA lesions during transthoracic ultrasound examination had the diagnosis confirmed at postmortem examination, while sheep without ultrasonographic changes characteristic of OPA had no gross lesions of OPA at postmortem examination. This demonstrates the specificity of transthoracic ultrasound for diagnosis of OPA. The authors propose that, in the absence of any other reliable preclinical diagnostic test, the use of transthoracic ultrasound examination should be considered for a second opinion on an initial diagnosis of OPA, for screening purchased adult flock replacements for OPA, or for screening sheep in a known OPA-affected flock. However, the authors emphasise that a negative scan cannot provide a guarantee that the animal is free of JSRV infection nor early OPA.

Long-term study of ovine pulmonary adenocarcinogenesis in sheep with marginal vs. sufficient nutritional selenium supply: results from computed tomography, pathology, immunohistochemistry, JSRV-PCR and lung biochemistry

The impact of selenium (Se) in carcinogenesis is still debatable due to inconsistent results of observational studies, recent suspicion of diabetic side effects and e.g. dual roles of glutathione peroxidases (GPx). Previously, our group introduced long-term studies on lung carcinogenesis using the jaagtsiekte sheep retrovirus (JSRV) induced ovine pulmonary adenocarcinoma (OPA) as an innovative animal model. The present report describes the results of sufficient (0.2 mg Se/kg dry weight (dw)) vs. marginal (<0.05 mg Se/kg dw) nutritional Se supply on cancer progression over a two-year period in 16 animals. Computed tomography (CT) evaluation of lung cancer progression, final pathological examination, evidence of pro-viral JSRV-DNA in lung, lymph nodes and broncho-alveolar lavage cells as well as biochemical analysis of Se, GPx1 and thioredoxin reductase (TrxR) activity in lung tissue were recorded. Additionally, immunohistochemical determination of GPx1 expression in unaffected and neoplastic lung cells was implemented. The feeding regime caused significant differences in Se concentration and GPx1 activity in lung tissue between groups, whereas TrxR activity remained unaffected. JSRV was evident in broncho-alveolar lavage cells, lung tissue and lung lymph nodes. Quarterly executed CT could not demonstrate differences in lung cancer proliferation intensity. Necropsy and histopathology substantiated CT findings. Immunohistochemical analysis of GPx1 in lung tissue suggested a coherency of GPx1 immunolabelling intensity in dependence of tumour size. It was concluded that the model proved to be suitable for long-term studies of lung cancer proliferation including the impact of modifiable nutritional factors. Proliferation of OPA was unaffected by marginal vs. sufficient nutritional Se supply.