Assessing the validity of serodiagnostic test results.

When questionable serological results have been obtained from testing laboratories or test kits used in the clinic, the veterinarian either can accept the results at face value, and suffer the probable consequences of misdiagnoses, or take steps to ascertain if indeed the assay was properly validated and the result properly interpreted. It should not be assumed that assays offered by all commercial testing laboratories are fully validated. Neither should it be assumed that test kits, because they are licensed by the USDA, will give accurate answers to all serological questions. When evidence suggests that an assay was fully validated, test results produced by that assay still must be interpreted by the veterinarian within the context of the probability of disease for the patient or groups of animals before testing, or misclassification of infection/disease status of patients may occur. The astute veterinarian will take steps to clarify if the testing laboratory or the test kits being used are performing adequately. Additionally, all test results in that practice will be interpreted in the context of their predictive values. Simplified methods for accomplishing these goals in a timely manner have been provided and will lead to more reasoned clinical diagnoses.