Porcine Stress Syndrome (PSS) is also known as the Halothane Test (HAL) or Malignant Hyperthermia. PSS is a congenital, autosomal recessive genetically based disorder. It is characterised by a rapid internal body temperature increase and sudden death. The disorder can often be triggered when the animal encounters some sort of environmental stress such as being transported to a new location, overcrowding, or some other stressful situation. The disorder can also be induced by the use of the anaesthetic halothane. In addition to sudden death, other undesired effects include very poor meat quality, post slaughter, caused by a change in the PH of the muscle tissue. The genetic condition is most commonly found in Landrace, Piétrain, Poland China breeds as well as their crosses. It is not uncommon that homozygous affected animals have a more developed muscular stature compared to the average.
Quantitative Polymerase Chain Reaction (qPCR) and antibody based (ELISA) testing are used to detect the presence of the bad form of the Ryanodine Receptor (RYR) gene. Breeding strategies should include the removal, or at least selective breeding, of homozygous affected and carrier (heterozygous) pigs. Genetic testing can be done with blood spotted on a blood card, whole blood, tail clip, ear notch, hair root, or semen submissions.