PubMed · 11623539
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C H Klatt. 1998. [Not Available].. https://pubmed.ncbi.nlm.nih.gov/11623539/
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Single-locus disorders in domesticated animals were among the first Mendelian traits to be documented after the rediscovery of Mendelism, and to be included in early linkage maps. The use of linkage maps and (increasingly) comparative genomics has been central to the identification of the causative gene for single-locus disorders of considerable practical importance. The 'score-card' in domestic animals is now more than 100 disorders for which the molecular lesion has been identified and hence for which a DNA test is available. Because of the limited lifespan of any such test, a cost-effective and hence popular means of protecting the intellectual property inherent in a DNA test is not to publish the discovery. While understandable, this practice creates a disconcerting precedent. For multifactorial disorders that are scored on an all-or-none basis or into many classes, the effectiveness of control schemes could be greatly enhanced by selection on estimated breeding values for liability. Genetic variation for resistance to pathogens and parasites is ubiquitous. Selection for resistance can therefore be successful. Because of the technical and welfare challenges inherent in the requirement to expose animals to pathogens or parasites in order to be able to select for resistance, there is a very active search for DNA markers for resistance. The first practical fruits of this research were seen in 2002, with the launch of a national scrapie control programme in the UK.
Antimicrobial susceptibility testing was performed on a total of 581 clinical Escherichia coli isolates from diarrhea and edema disease in pigs, from acute mastitis in dairy cattle, from urinary tract infections in dogs and cats, and from septicemia in laying hens collected in Switzerland between 1999 and 2001. Among the 16 antimicrobial agents tested, resistance was most frequent for sulfonamides, tetracycline, and streptomycin. Isolates from swine presented significantly more resistance than those from the other animal species. The distribution of the resistance determinants for sulfonamides, tetracycline, and streptomycin was assessed by hybridization and PCR in resistant isolates. Significant differences in the distribution of resistance determinants for tetracycline (tetA, tetB) and sulfonamides (sulII) were observed between the isolates from swine and those from the other species. Resistance to sulfonamides could not be explained by known resistance mechanisms in more than a quarter of the sulfonamide-resistant and sulfonamide-intermediate isolates from swine, dogs and cats. This finding suggests that one or several new resistance mechanisms for sulfonamides may be widespread among E. coli isolates from these animal species. The integrase gene (intI) from class I integrons was detected in a large proportion of resistant isolates in association with the sulI and aadA genes, thus demonstrating the importance of integrons in the epidemiology of resistance in clinical E. coli isolates from animals.
Regarding national and international trade of animals and animal products, certificates are required to document specific health levels. The credibility of such certificates depends on the quality of the data used to establish the status. Credibility also depends on the quality of the design and protocols used in the data-gathering process (i.e. on the quality of the surveillance-and-monitoring systems (SMS) and on the quality of the veterinary administrative systems (VAdminS)). The major requirements for the assessment of the SMS and VAdminS are: objectivity, accuracy, transparency, practicality, quantitative in nature. To assess the quality of SMS and VAdminS, systems analysis might provide a suitable framework. Systems analysis requires the identification and description of all components of the system-how they interact with each other and with other systems. Graphical methods (e.g. fault trees) are available to support this procedure. To assess the quality of SMS, scoring systems have been suggested. Their main weakness is the inherent subjectiveness. Alternatively, performance indicators (PI) could be used. For the assessment of VAdminS, questionnaires have been developed and applied. Their main limitations are that they focus on the input rather than on the output and that they are purely descriptive in nature. Thus, comparisons between countries are almost impossible. Semi-quantitative questionnaires using scores now are being developed and tested, although their limitations will be similar to those mentioned above. Another approach is the use of risk assessment including standardised data files assembled by countries volunteering to be assessed. This was applied successfully by the European Union (EU) in the geographic risk assessment for bovine spongiform encephalopathy (BSE). In general, the publication and documentation of veterinary systems needs to be encouraged to make them accessible to peer review.