Residues from long-acting antimicrobial preparations in injection sites in cattle

Objective To investigate tissue residues of two longacting oxytetracycline (OTC) preparations in cattle.
Design A randomised drug residue trial.  

Animals

Two hundred and forty beef cattle in 24 groups of ten.
Procedure Two blind-coded 200 mg/mL OTC preparations were used in five treatment regimens of various combinations of injection sites (from one to five) and administrations (one or two). Five cattle from each group were slaughtered at 21, 30 and 60 days after injection and the injection site, urine, kidney and diaphragm muscle analysed for residues.
Results The OTC concentration exceeded the maximum residue limit in kidney in animals slaughtered 21 days after treatment, which is the prescribed withholding period. Concentration at the injection site was much greater than the maximum residue limit 30 days post-treatment, but not 45 days post-treatment. The residue was smaller when OTC had been injected in multiple sites. There was no difference between the two OTC preparations.
Conclusion A review of the maximum injection volume, site of injection and the withholding period is needed for long-acting OTC formulations.     

Length of veterinary working life

Objective To estimate the time veterinary graduates spend in private practice and in veterinary work generally, and to determine what factors influence this.
Methods Questionnaires were completed in the sixth year after graduation by 119 veterinarians who had participated in this longitudinal study since starting the veterinary course, and the data were analysed using the SAS System for Windows.
Results Of those who started the veterinary course, 90% graduated, and 96% of these then entered private practice. Five years later 94% (73% in full-time equivalents) were working as veterinarians, and 64% (50% in full-time equivalents) were still in private practice in Australia. Hours, attitudes of principals and clients, and inadequate rewards were the main reasons for leaving private practice. The likelihood of being still in private practice was greater for those who had had significant responsibility for animals before they entered the course, but it was not related to geographical origin (city vs country), age at entry or gender. Women were, however, more likely than men to be working part time as veterinarians. Predictions of veterinary working life were not affected by geographical origin or by previous experience with animals or on farms, but men expected to work longer than women.
Conclusion The average veterinary career, estimated by veterinarians who graduated 5 years earlier, is 24 years in fulltime equivalents for men, and 16 years for women. Almost all (94%, representing 73% in full-time equivalents) still work as veterinarians after 5 years, most of them (76%, representing 59% in full-time equivalents) in private practice. The likelihood of remaining in private practice is related to previous responsibility for animals.     

Entrepreneurship and Extraregional Trade in the Producer Services

Traditional explanations of interaction (trade) in city systems fail to capture the breadth and complexity of extraregional markets in the producer services. Building on market-process theory, which argues that markets are adaptive and rarely in equilibrium, the development of extraregional trade in the producer services was investigated as a form of firm-level entrepreneurship. While firms' entrepreneurial behaviors are influenced by a variety of internal characteristics, such as entrepreneurial spirit, size, age, and ownership, it is argued that a firm's location is an important conditioning factor on the degree of success it achieves with market expansion. The hypothesis is evaluated using spatial market extent data developed from a survey of 615 producer service firms located in 16 Midwest cities. A firm's degree of entrepreneurship is indexed by a qualitative assessment of its marketing activities, ranging from “aggressive” to “none.” Cox proportional hazards models, in a spatial-analog of survival analysis, were used to examine the influence of entrepreneurship on the spatial extents of firms' markets. The results confirm that location, more so than firm size or age, has a significant influence on the spatial extent of a firm's extraregional trade. The influence of location is generally complex: surfacing directly as a market scale effect, and indirectly as a conditioning factor on the success of a firm's entrepreneurial behavior. The results suggest that extraregional trade in producers services is predicated on more than just production cost (i.e., internal or external scale economies) or distribution cost (i.e., distance) factors, and that behavioral theories of the market can provide meaningful insight into the geography of market interaction.     

The diagnosis and treatment of a thoracic abscess in an alpaca

A 6-month-old alpaca presented for lethargy, failure to thrive and leucocytosis. Diagnostic procedures, including thoracic ultrasound, radiographs and a computed tomography scan, were used to document a thoracic mass. Based on appearance and ultrasound-guided aspiration of purulent material, the mass was determined to be a large abscess. The abscess was treated with surgical drainage and long-term antibiotic therapy. The origin of this thoracic abscess was felt to be the caudal mediastinum, secondary to bacterial seeding of the caudal mediastinal lymph nodes. Although an aetiological agent was not definitively determined, the most likely was Actinomyces spp or Arcanobacterium pyogenes. The alpaca made a complete recovery following treatment.     

Stratospheric Mean Ages and Transport Rates from Observations of Carbon Dioxide and Nitrous Oxide

Measurements of stratospheric carbon dioxide (CO2) and nitrous oxide (N2O) concentrations were analyzed to investigate stratospheric transport rates. Temporal variations in tropospheric CO2 were observed to propagate into the stratosphere, showing that tropospheric air enters the lower tropical stratosphere continuously, ascends, and is transported rapidly (in less than 1 month) to both hemispheres. The mean age A of stratospheric air determined from CO2 data is approximately 5 years in the mid-stratosphere. The mean age is mathematically equivalent to a conserved tracer analogous to exhaust from stratospheric aircraft. Comparison of values for A from models and observations indicates that current model simulations likely underestimate pollutant concentrations from proposed stratospheric aircraft by 25 to 100 percent.