Reproducibility is the ability of an assay to provide consistent results (when testing the same samples) in different laboratories. The validation of a new diagnostic assay should include specific assessment of assay reproducibility to determine the degree to which results are unaffected by minor changes in experimental conditions. Ideally, assessment of reproducibility involves the testing of identical samples in multiple laboratories by multiple analysts using the same method, reagents and controls, albeit with different equipment. Such an assessment will provide estimates of the precision and accuracy of an assay across laboratories. In reality, although the reproducibility of an assay is often assessed by multiple laboratories testing identical samples, the reagents, controls and testing platforms used, while similar, are usually not the same.  https://www.selleckchem.com/products/skf38393-hcl.html  Thus, reproducibility testing permits the assessment of variability resulting from different testing platforms, reagent supplies and operators. The determination of minor versus major variations in test conditions that may be anticipated in multi-laboratory use is part of the assessment at this stage of validation. Once validated, there are ongoing monitoring requirements to assess the performance characteristics and ensure they are consistently maintained. The use of quality assurance programmes is required, as this offers continued monitoring of assay performance by measuring the precision and accuracy of results for well-characterised samples and controls. Tests recommended by the World Organisation for Animal Health as fit for purpose are widely used internationally and need to have satisfactory reproducibility.This paper focuses on several new diagnostic technologies, which are set to dominate the testing landscape in the near future and have applications in animal health diagnostics, namely next-generation sequencing, assays to detect biomarkers, and point-of-care tests. An example of real-time loop-mediated isothermal amplification validation is also provided. Validating these new technologies presents several challenges, which are addressed in this paper.In the field of diagnostic test validation, World Organisation for Animal Health (OIE) Reference Laboratories (RLs) have a pivotal role and provide the international community with impartial advice and support in the selection, development and validation of diagnostic tests, which can be applied to the specialist diseases for which they are designated. National RLs provide an invaluable function in supporting the introduction, ongoing validation and application of validated diagnostic tests in line with international standards. Experienced staff with extensive knowledge of such systems and access to specialist facilities for conducting work are available to monitor changes or advancements in technology. They consider their relevance and value to evolving diagnostic test requirements. Reference Laboratories often have a broad mandate of activity linking research or development programmes and surveillance activities to benefit the continual assessment and, if necessary, improvement of diagnostic tools. Referenc systems underpinning test validation.In the field of diagnostic test validation, World Organisation for Animal Health (OIE) Reference Laboratories (RLs) have a pivotal role and provide the international community with impartial advice and support in the selection, development and validation of diagnostic tests, which can be applied to the specialist diseases for which they are designated. National RLs provide an invaluable function in supporting the introduction, ongoing validation and application of validated diagnostic tests in line with international standards. Experienced staff with extensive knowledge of such systems and access to specialist facilities for conducting work are available to monitor changes or advancements in technology. They consider their relevance and value to evolving diagnostic test requirements. Reference Laboratories often have a broad mandate of activity linking research or development programmes and surveillance activities to benefit the continual assessment and, if necessary, improvement of diagnostic tools. Referenc systems underpinning test validation.The validation of diagnostic methods (and the subsequent results generated by a laboratory) are improved through participation in inter-laboratory comparisons (IC), such as proficiency-testing (PT) programmes and other exercises referred to as 'ring tests' or 'ring trials' (RTs). This is a requirement to comply with international quality standards. Validating a method is a continuous process and taking part in ongoing PT programmes supports the management of a method's life cycle, providing continuing assessment of fitness (sometimes referred to as the 'validation retention status'). Proficiency-testing panel designs ensure that the methods used, particularly diagnostic specificity and sensitivity, are suitably challenged. Appraising PT results over time can illustrate whether the laboratory's performance is stable, improving or worsening, and proficiency tests can also highlight variations in the performance of assays. The development of new proficiency tests can support the implementation of novel diagnostists.A reliable laboratory assay is an essential tool for the diagnosis or surveillance of most animal diseases. Before routine use, assays should be appropriately validated to ensure that they have performance characteristics that provide reliable results and can be used for the intended purpose. It is inevitable that, over time, changes will need to be made to assay reagents, to the assay format, to test a different species or for implementation in a new laboratory. Whenever there is a change (whether it be components, application or location), it is essential to establish whether the new circumstances affect the biological basis and properties of the assay. If the modifications do not affect the biological basis of the assay, the changes might be considered minor and a verification study can be conducted to confirm that the performance characteristics have not been adversely affected. Major changes require a new validation to be carried out. A method comparability study, where original and modified assays are run concurrently to test the same sample panel, provides an extremely robust comparison.