Diagnostic value of serum creatine phosphokinase activity for the porcine malignant hyperthermia syndrome.

Serum creatine phosphokinase (CPK) activity was measured in 10 German Landrace pigs from 11 to 28 weeks of age. A pronounced age dependence of serum enzyme activity was observed, peak activity occurring at 19 weeks of age. At the end of the growth period, when the pigs were challenged with halothane to detect the malignant hyperthermia syndrome, 3 pigs were found to be susceptible. Singificant increases in the serum enzyme levels in the susceptible pigs were observed only at 11 and 28 weeks of age. Serum enzyme levels measured during the rapid phase of growth could not be used to predict the malignant hyperthermia syndrome. Elevated serum CPK levels were also observed in two litters of Large White and Landrace x Large White pigs, breeds known to be stress-resistant. No pigs in these litters were susceptible to halothane, even though CPK levels were similar to those of the German Landrace pigs. The results indicate that serum CPK levels can be used as evidence of predisposition to the malignant hyperthermia syndrome but cannot be relied on as a single ultimate test.