Ovine Johne's disease: the risk associated with sheep imported into Western Australia

Objective To assess the risk of Johne's disease not being detected in sheep imported from New South Wales into Western Australia.
Design A stochastic simulation model.
Procedure The process of importing sheep was broken down into steps and numbers or probabilities assigned to each. Controls on the movement of sheep included surveillance tests in source flocks and serological tests on sheep in consignments before and after transportation to Western Australia. The model calculated the risk of occurrence of Johne's disease in Western Australia and the success of the agar gel immunodiffusion test in identifying consignments with infected sheep.
Results Negative surveillance tests in source flocks reduced the risk to about one twentieth of that when no surveillance tests were required. On average, Johne's disease was predicted to be introduced once in every 3 to 7 years when no testing of either the source flock or the sheep in consignments was required. When negative surveillance tests only were required the interval increased to once in every 63 to 111 years and, with the additional requirement that all sheep in each consignment must have a negative test before and after transport, the interval further increased to once in every 125 to 333 years. When only sheep in consignments were tested, the interval was calculated to be 8 to 14 years.
Conclusion A requirement that imports be derived from flocks which had negative surveillance tests to Johne's disease would provide significantly greater protection for the sheep industry in Western Australia.     

Toxicologic evaluation of chlorpyrifos in cats

Twenty-four male domestic shorthair cats were used to evaluate the acute and chronic effects of a single, toxic but sublethal, orally administered dose of chlorpyrifos. A dosage of 10 mg/kg of body weight did not induce clinical signs of toxicosis, but a dosage of 40 mg/kg induced clinical signs of toxicosis, and 1 of 12 cats died. Chlorpyrifos given at a dosage of 0.1 mg/kg to 2 cats reduced whole blood and plasma cholinesterase (Che) activities to values obtained after cats were given doses that induced clinical signs of toxicosis. Regeneration time for whole blood and plasma Che activities ranged from 7 to 28 days. Brain Che activity was considerably decreased in 1 cat that died 4.5 hours after dosing, but was normal in all others at 28 days after dosing. Other than decreased Che activity, significant changes were not seen in hematologic or serum biochemical values. Toxin-related lesions were not seen during macroscopic or microscopic examination.     

The incidence, cost and factors associated with foot lameness in dairy cattle in south-western Victoria

A survey of 73 dairy farms in south-western Victoria was conducted to assess the cost and mean herd incidence of foot lameness for the period from calving to the end of November, 1985, and to identify the herd, management and environmental factors associated with foot lameness. The mean herd size was 125 cows (range 82 to 220). Lameness occurred in 64 (88%) herds, and the mean herd incidence was 7.0% (range 0.0 to 30.9%). The main clinical signs associated with lameness were the presence of overworn and/or bruised soles, or stones lodged in the interdigital cleft. Factors associated with lameness were: property and herd size, age of cow, bail feeding, voluntary entry into the bails, and features of the farm track including its length, the presence of steep slopes, the type of surface material, presence and treatment of broken sections and maintenance including rolling history. The association of these factors with specific clinical signs was examined. The mean cost was estimated to be $42.90 per lame cow due to loss of production, treatment, the culling or death of lame cows, and extra man hours spent managing lame cows. It was concluded that the site, construction, maintenance and use of the farm track were of major importance to the incidence of lameness in herds in this area and recommendations for reducing lameness are made.     

Behavioural diversity in fishing—Towards a next generation of fishery models

Despite improved knowledge and stricter regulations, numerous fish stocks remain overharvested. Previous research has shown that fisheries management may fail when the models and assessments used to inform management are based on unrealistic assumptions regarding fishers' decision‐making and responses to policies. Improving the understanding of fisher behaviour requires addressing its diversity and complexity through the integration of social science knowledge into modelling. In our paper, we review and synthesize state‐of‐the‐art research on both social science's understanding of fisher behaviour and the representation of fisher decision‐making in scientific models. We then develop and experiment with an agent‐based social–ecological fisheries model that formalizes three different fishing styles. Thereby we reflect on the implications of our incorporation of behavioural diversity and contrast it with the predominant assumption in fishery models: fishing practices being driven by rational profit maximizing. We envision a next generation of fisheries models and management that account for social scientific knowledge on individual and collective human behaviours. Through our agent‐based model, we demonstrate how such an integration is possible and propose a scientific approach for reducing uncertainty based on human behavioural diversity in fisheries. This study serves to lay the foundations for a next generation of social–ecological fishery models that account for human behavioural diversity and social and ecological complexity that are relevant for a realistic assessment and management of fishery sustainability problems.     

Skeletal muscle rhabdomyosarcomas in inbred laboratory mice.

A total of 14 well differentiated rhabdomyosarcomas were diagnosed at necropsy in 10,000 mice. Of the 14 affected mice, ten were BALB/cJ, and there was one case each of A/HeJ, BALB/cByJ, C58/J, and C.B-17-scid/scid strains. Most often (10/14) tumors originated in the quadriceps muscles and metastases occurred in six cases. When submitted, affected mice were 2 to 8 months of age, with a mean age of 4 months. Tumor frequency for BALB/cJ mice was calculated to be 2.4/100,000 mice retained as breeders. No sexual dimorphisms were determined when data were correlated to actual numbers of each sex in the colony. All 14 primary tumors and metastases were positive by immunohistochemistry for the proteins pan myosin, sarcomeric actin, desmin, actin, and myosin, but were negative for smooth muscle actin, thus confirming the diagnosis. Using cell free homogenates of primary tumors, inoculated by intraperitoneal or intramuscular injection, tumors were not induced in either BALB/cJ or C58/J mice observed over a 22-week period. Southern blot analysis of DNA prepared from tumors and hybridized with a murine leukemia virus probe that recognizes both ecotropic and dualtropic viruses did not demonstrate viral genomic fragments in addition to those known to occur in each strain.     

Myoepitheliomas in inbred laboratory mice.

Myoepitheliomas are subcutaneous tumors that arise from myoepithelial cells of various exocrine glands. In a retrospective study of 142 tumors observed over a period of 3 years, myoepitheliomas occurred spontaneously in A/HeJ, A/J, BALB/cJ, BALB/cByJ, LLC.A/Ckc, and NOD/Lt inbred strains of mice. Tumors presented primarily in the subcutaneous tissues of the ventral neck (74% of the myoepitheliomas evaluated) but were observed in several other subcutaneous locations, including the head, perineum, and ventral abdomen. These areas were adjacent to salivary, mammary, clitoral, preputial, and Harderian glands. Forty myoepitheliomas were tested by the avidin-biotin complex technique with a panel of antisera specific for mouse keratins, intermediate filaments, and other cytoskeletal proteins to determine the cell type from which this neoplasm originated. Antibodies directed against the specific mouse keratins K5, K6, and K14, and a broadly cross-reactive cytokeratin antibody stained acinar and ductal myoepithelial cells in normal mammary, salivary, and Harderian glands, and neoplastic cells in all cases. Antisera directed against a smooth muscle actin (anti-alpha-sm-1) stained acinar myoepithelial cells of the glands and vascular smooth muscle but neither ductular myoepithelial cells nor tumor cells. This supports the notion that these tumors originate from extraglandular ductular myoepithelial cells. Southern blots, prepared from DNA extracted from nine myoepitheliomas, did not show restriction fragment length polymorphisms when mouse mammary tumor virus (MMTV) cDNA or Int-1 genomic DNA probes were used; this implies that a retrovirus is not the etiologic agent.