Epidemiologic issues in the validation of veterinary diagnostic tests

In this review, we critically discuss the objectives, methods and limitations of different approaches for the validation of diagnostic tests. We show (based on published data and our own experiences) that estimates for the diagnostic sensitivity and specificity may vary among populations and/or subpopulations of animals, conditional on the distribution of influential covariates. Additional variability in those parameter estimates may be attributable to the sampling strategy. The uncertainty about diagnostic parameters is of concern for the decision-maker in the context of clinical diagnosis or quantitative risk assessment as well as for the epidemiologist who uses test data for prevalence estimation or risk-factor studies. Examples for the calculation of diagnostic parameters are presented together with bias-avoidance strategies. We suggest guidelines for an epidemiologic approach to test validation of veterinary diagnostic tests.     

Development and validation of a questionnaire for measuring behavior and temperament traits in pet dogs

OBJECTIVE: To develop and validate a questionnaire to assess behavior and temperament traits of pet dogs. DESIGN: Cross-sectional survey of dog owners. Animals-1,851 dogs belonging to clients of a veterinary teaching hospital or members of national breed clubs and 203 dogs examined by canine behavior practitioners because of behavior problems. PROCEDURE: Owners were asked to complete a questionnaire consisting of 152 items eliciting information on how dogs responded to specific events and situations in their usual environment. Data from completed questionnaires were subjected to factor analysis, and the resulting factors were tested for reliability and validity. RESULTS: Factor analysis yielded 11 factors from 68 of the original questionnaire items that together accounted for 57% of the common variance in questionnaire item scores. Reliability was acceptable for all but 1 of these factors. Behavior problems in 200 of the 203 dogs with behavior problems could be assigned to 7 diagnostic categories that matched 7 of the factors identified during factor analysis of questionnaire responses. Dogs assigned to particular diagnostic categories had significantly higher scores for corresponding questionnaire factors than did those assigned to unrelated diagnostic categories, indicating that the factors were valid. Validity of the remaining 4 factors could not be examined because of a lack of information on dogs with behavior problems related to these factors. CONCLUSIONS AND CLINICAL RELEVANCE: Findings suggest that the resulting 68-item questionnaire is a reliable and valid method of assessing behavior and temperament traits in dogs. The questionnaire may be useful in screening dogs for behavior problems and in evaluating the clinical effects of various treatments for behavior problems.