Porcine stress syndrome and PSE meat: clinical symptoms, pathogenesis, aetiology and aspects of animal welfare

A review is given about the clinical symptoms, pathogenesis and aetiology o f the porcine stress syndrome, furthermore aspects of animal welfare are di scussed. The current breeding programmes of pig industry in Germany in many cases in clude animals with a mutation of the ryanodine-receptor (RYR-1)-gene - homo zygous or heterozygous. This situation is the result of an intensive bleedi ng of pigs during the last decades with the intention of increased lean car cass content and corresponding proceeds. The homozygous pigs are more stres s susceptible (porcine stress syndrome) and produce meat of poor quality (P SE). which is also the case to some extend in heterozygous animals. The cli nical symptoms of this muscle disease are characterised by a deficit of oxy gen and a rapid glycolysis accompanied by a production of lactic acid and a cidosis primarily in II B white muscle fibres. There is no doubt that a ver y close causal relation exists between the mutation of the RYR-1 and the po rcine stress syndrome as well as the poor meat quality. The present knowled ge of this disease, the genetic back ground, the physiology and pathophysio logy of the mutation of the RYR-1 leads to the imperative conclusion to eli minate this mutated RYR-1 by selection of healthy pigs, which has been done successfully in other countries with important pig production. This conclu sion is also supported by simple economic reasons because fertility. reprod uction and daily weight gain are significantly reduced in stress susceptibl e pigs. Furthermore, it should be emphasised that regular breeding with the mutated RYR-1 is also a matter of animal welfare. The evident correlation between the mutated RYR-1 and the porcine stress syndrome, which includes d egeneration of the muscle, pain and even life threatening malignant hyperth ermia, can easily lead to the accusation in the public that diseased animal s are used for pig meat production. Consequently, the authors would like to urge the breeding companies and the responsible authorities to discuss the problem with the intention to finish the current breeding programmes using animals with the mutated RYR-1 within a reasonable period of time.