Changes

It can also be induced by exposure to certain anaesthetics, most markedly '''halothane''' (which can also generate the disease in people), intense exercise, coitus, parturition and transport.

It can also be induced by exposure to certain anaesthetics, most markedly '''halothane''' (which can also generate the disease in people), intense exercise, coitus, parturition and transport.

PSS leads to an increase in metabolism and intense production of '''heat, carbon dioxide and lactic acid and contraction of skeletal musculature'''.<ref> Gronert, G. A (1986) '''Malignant hyperthermia'''. In: Engle, B., Banker, B. eds. '''Myology'''. ''New York, USA: McGraw Hill'', 1763-1783</ref> The fall in muscle pH following slaughter causes '''denaturation of muscular proteins, myofibre shrinkage and the pale, soft and exudative (PSE) appearance''' of the pork. PSS mainly affects the Type IIB muscle fibres.

PSS leads to an increase in metabolism and intense production of '''heat, carbon dioxide and lactic acid and contraction of skeletal musculature'''.<ref> Gronert, G. A (1986) '''Malignant hyperthermia'''. In: Engle, B., Banker, B. eds. '''Myology'''. ''New York, USA: McGraw Hill'', 1763-1783</ref>  

PSS is not zoonotic. Although PSS meat is of poor quality and poor aesthetic appeal, it is not a hazard on its own.

PSS appears as three different syndromes:

:'''Pale, soft and exudative (PSE) meat''' in which the fall in muscle pH following slaughter causes denaturation of muscular proteins and myofibre shrinkage. PSS mainly affects the Type IIB muscle fibres. The meat is of poor quality and is rejected in the abattoir.

 

PSS is not zoonotic.

==Distribution==

==Distribution==

'''Worldwide'''. Prevalence is dictated by emphasis on quality or quantity of meat produced and cultural/traditional differences in pig selection and production.

'''Worldwide'''. Prevalence is dictated by emphasis on quality or quantity of meat produced and cultural/traditional differences in pig selection and production.

==Signalment==

==Signalment==

The genetic trait is most commonly manifested in '''Landrace, Poland-China, Pietrain''' and associated crossbreeds. Because affected pigs often have more developed musculature and therefore larger carcass weights, the genes translating PSS are often favoured when selecting breeding stock.

The genetic trait is most commonly manifested in '''Landrace, Poland-China, Pietrain''' and associated crossbreeds. Historically, because affected pigs often had more developed musculature and therefore larger carcass weights, the genes translating PSS were often favoured when selecting breeding stock. This is now not standard practice in the developed world.

==Clinical Signs==

==Clinical Signs==

Affected pigs undergoing an episode of PSS will be '''hyperthermic, panting, sweating excessively, markedly tachycardic with possible arrhythmias, trembling, hypertonic''', stiff or paretic, lame and sometimes '''cyanotic'''. Muscle atrophy may be evident, usually of large muscle groups around the back and hindlimbs. The skin often becomes '''blotchy, erythematous and cyanotic.  

Pigs may be '''found dead''', particularly after times of stress, e.g. transport.

Haemoglobinuria/myoglobinura''' is a common consequence of muscle damage/lysis.

Before death, affected pigs will have been '''hyperthermic, panting, sweating excessively, markedly tachycardic with possible arrhythmias, trembling, hypertonic''', stiff or paretic, lame and sometimes '''cyanotic'''. Muscle atrophy may be evident, usually of large muscle groups around the back and hindlimbs. The skin often becomes '''blotchy, erythematous and cyanotic.  

Pigs may be '''found dead''', particularly after times of stress, e.g. transport.

'''Haemoglobinuria/myoglobinura''' is a common consequence of muscle damage/lysis.

Early signs of disease may be '''tail tremors''' and fine fasciculations.  

Early signs of disease may be '''tail tremors''' and fine fasciculations.  

PSS pigs will '''develop rigor mortis very rapidly''' after slaughter and there will be significant economic losses from rejected meat.

'''PSE''' will appear as inadequate setting of the carcase after slaughter and significant economic losses from rejected meat.

 

'''Malignant hyperthermia''' will occur during anaesthesia under halothane, and will appear as significant muscle contractions, pyrexia and muscle rigidity.

==Diagnosis==

==Diagnosis==

Testing breeding stock or suspect animals and eliminating them from breeding stock is ideal, but often poorly accepted due to the favourable characteristics of PSS animals.  

Testing breeding stock or suspect animals and eliminating them from breeding stock is ideal, but often poorly accepted due to the favourable characteristics of PSS animals.  

{{Learning

{{Learning

|date =3 July 2011

|date =3 July 2011

}}

}}

<br><br><br>

<br><br>

 

[[Category:CABI Expert Review]] [[Category:Musculoskeletal Diseases - Pig]]

[[Category:CABI Expert Review]] [[Category:Musculoskeletal Diseases - Pig]]

[[Category:Muscles - Developmental Pathology]]

[[Category:Muscles - Developmental Pathology]]