Identification of susceptibility to malignant hyperpyrexia in swine.

In vitro muscle contracture responses in swine susceptible to malignant hyperpyrexia (MH) were similar to those found in muscle from humans susceptible to this anaesthetic complication, confirming the suitability of the pig as an animal model for studying MH. The results suggest that there are different degrees of susceptibility to MH. Whichever drug was used, there was some overlap in the contracture responses between susceptible animals and controls, suggesting that the most accurate way of identifying susceptibility to MH is to use a variety of chemical agents, the best of which seem to be halothane, caffeine, suxamethonium and potassium chloride. Thymol, which is used as a preservative in commercial preparations of halothane, potentiates halothane contractures, but it is not known if this is significant clinically.