Porcine Stress Syndrome By Rushda Khan

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Porcine Stress SyndromeBy Rushda Khan

• By Rushda Khan

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Introduction

• Malignant hyperthermia
• Hypermetabolic syndrome
• Pig highly susceptible to stress
• Pietrain, Poland China, Duroc, Large White
• Consequences for meat quality

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Across species summary

• Humans, pigs, cats, dogs and horses.
• Dramatic rise in body temperature
• Various symptoms
• Volatile anaesthetics

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Species summary and History

• Transport or social stress
• Hot weather
• PSE meat
• Humans Unexplained anaesthetic deaths
• First case in Australia in 1962 in humans

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Clinical summary

• Muscular stiffness
• Tachycardia and tachypnea
• Cardiotoxic serum potassium levels
• Blanching and erythema
• Elevated core body temperature

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Generalized oedema and frothy exudates from
trachea
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Red skin (rash)

• Modern hybrid pigs
• Show lesions of erythema when restrained.
• Could die if not released quickly
• Associated with stress susceptibility and PSS

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Back Muscle Necrosis

• Special manifestation in animals gt 50 kgs.
• Curvature of the body towards affected side

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Pathology summary

• Ryanodine receptor floods myoplasm of skeletal
  muscle with calcium
• Muscle contracture and hypermetabolism
• ATP depleted
• Increased aerobic and anaerobic metabolism
• Co2 and lactic acid produced
• Rhabdomyolysis
• Death occurs due to an increase in serum
  potassium
• Cardiac dysrhythmia and arrest

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Prevalence and Inheritance

• Greater than 90
• Higher in lean, heavily muscled breeds
• Mortality around 3.2
• Autosomal recessive gene with variable penetrance
• Mutation in ryanodine receptor

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Molecular genetics

• At least 70 mutations in ryanodine receptor have
  been described
• Long arm of 19th chromosome (19q13.1)
• MH1 and 2 N-terminus
• MH3 C-terminus

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Genotype test and control

• Use of halothane
• DNA based assays
• Select against trait
• Economic consequences
• Some breeds extinct
• Good animal husbandry and management practices

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Treatment

• Dantrolene sodium
• Fluid therapy
• Management of acidosis
• Oxygen enrichment
• Treatment of cardiac dysrhythmias
• Unexplained anaesthetic or transport deaths

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Consequences for meat quality

• Unusually high rate of PM glycolysis
• PSE meat
• (Pale, soft, exudative)
• Poor quality

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References

• The Encyclopaedia of Animal Science
• The Merck Veterinary Manual (9th edition)
• Pig Production
• A Colour Atlas on Diseases and Disorders of the
  Pig