title: Latent class evaluation of a milk test, a urine test, and the fat-to-protein percentage ratio in milk to diagnose ketosis in dairy cows.
abstract: In this study, 3 commonly used tests to diagnose ketosis were evaluated with a latent class model to avoid the assumption of an available perfect test. The 3 tests were the KetoLac BHB (Sanwa Kagaku Kenkyusho Co. Ltd., Nagoya, Japan) test strip that tests milk for β-hydroxybutyrate, the KetoStix (Bayer Diagnostics Europe Ltd., Dublin, Ireland) test strip that tests urine for acetoacetate, and the fat-to-protein percentage ratio (FPR) in milk. A total of 8,902 cows were included in the analysis. The cows were considered to be a random sample from the population of Danish dairy cattle under intensive management, thus representing a natural spectrum of ketosis as a disease. All cows had a recorded FPR between 7 and 21 d postpartum. The KetoLac BHB recordings were available from 2,257 cows and 6,645 cows had a KetoStix recording. The recordings were analyzed with a modified Hui-Walter model, in a Bayesian framework. The specificity of the KetoLac BHB test and the KetoStix test were both high [0.99 (0.97-0.99)], whereas the specificity of FPR was somewhat lower [0.79 (0.77-0.81)]. The best sensitivity was for the KetoStix test [0.78 (0.55-0.98)], followed by the FPR [0.63 (0.58-0.71)] and KetoLac BHB test [0.58 (0.35-0.93)].
authors.affiliation: Department of Large Animal Sciences, Faculty of Life Sciences, University of Copenhagen, Grønnegårdsvej 2, DK-1870 Frederiksberg C, Denmark. mok@life.ku.dk
authors.forename: M A
authors.initials: MA
authors.lastname: Krogh
authors.forename: N
authors.initials: N
authors.lastname: Toft
authors.forename: C
authors.initials: C
authors.lastname: Enevoldsen
mesh_terms: D020155:3-Hydroxybutyric Acid / Q000032:analysis; D000090:Acetoacetates / Q000652:urine*; D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000175:diagnosis* / Q000652:urine; D004041:Dietary Fats / Q000032:analysis; D005260:Female; D007662:Ketosis / Q000175:diagnosis / Q000652:urine / Q000662:veterinary*; D008892:Milk / Q000737:chemistry*; D008894:Milk Proteins / Q000032:analysis; D011933:Reagent Kits, Diagnostic / Q000662:veterinary*; D012680:Sensitivity and Specificity
chemical_list: D000090:Acetoacetates; D004041:Dietary Fats; D008894:Milk Proteins; D011933:Reagent Kits, Diagnostic; D020155:3-Hydroxybutyric Acid