Blood creatine kinase as a predictor of the porcine stress syndrome.

Gilts, barrows and boars of Pietrain (P), Yorkshire (Y) and P-Y-Hampshire (H) breeding, Px P (PHY), were used to study accuracy of prediction of susceptibility to the porcine stress syndrome (PSS) by the luciferase method for blood creatine kinase (CK). At 10 weeks of age, pigs were classified as PSS if they displayed muscle rigidity within 5 min after commencing anesthesia with 3% halothane in oxygen. At 28 weeks, blood was obtained 8 hr after exercise, CK determined, and the CK value used to retrospectively predict PSS classification (PSS+ or PSS-) as determined by the halothane test. For Yorkshire pigs (all PSS) the mean CK level was 395 IU/liter. Therefore, for purposes of classifying pigs as PSS or normal via the blood CK level, 400 IU/liter was selected as the upper limit of classification of pigs as normal. A true positive outcome was defined as a PSS pig (halothane-induced rigidity) which displayed a CK value greater than 400 IU/liter blood. A normal pig (PSSby halothane test) with greater than 400 IU/liter was considered a false positive. The number of true positive, false positive, true negative and false negative outcomes were as follows: for P-77, 6, 0 and 4; for Y-O, 8, 18 and 0; for PxP (PHY)-7, 5, 8 and 0; for all groups-84, 19, 26 and 4, respectively. Prevalence of PSS-susceptibility, based on response to halothane exposure, was 89, 0, 35 and 63% for P, Y, P• P (PHY) and all groups, respectively. Accuracy of prediction [(number correct + total) • 100] of PSS-susceptibility by blood CK was 89, 69, 75 and 83% for P, Y, Px P (PHY) and all groups, respectively. The resuits of this study would suggest that the luciferase procedure for blood CK is a useful screening method for PSS. The efficacy of the method is influenced by prevalence o f PSS in the breed being studied. (