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Actinobacillus Pleuropneumonia (App)

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The bacterium Actinobacillus pleuropneumoniae (App) consists of at least twelve different serotypes, some of which produce no disease but others cause severe disease. Serotypes vary in different countries. Types 1, 5, 9, 11 and 12 are usually highly virulent and strains 3 and 6 are mild. App is carried in the tonsils and upper respiratory tract. It is transmitted short distances by droplet infection and only survives outside the pig for a few days.

The organism may affect the pig from weaning through to slaughter but usually the age is from 8 to 16 weeks. The incubation period is very short, as little as 12 hours. Toxins produce severe damage to the lungs.

App is uncommon in sows unless they are naive or disease is triggered by PRRS or flu.


All Pigs
  • Unusual in adult and very young pigs unless a naive herd.
  • Sudden death/mortality may be low or high - only sign a bloody discharge from the nose.
  • Sudden death/mortality - no symptoms and more than 1 % of such deaths. Post mortems required.
  • A short cough perhaps 1 to 3 coughs at a time - different from the prolonged coughing of EP.
  • Severe heavy breathing difficulties.
  • Blueing of the ears.
  • Badly affected pigs are:
      - Severely depressed.
      - Off feed.
      - Body temperatures are high.
  • Pleurisy.
  • Haemorrhage from the nose.
  • Lameness - occassionally.
  • Pale pigs.
  • Pneumonia.
  • Poor pigs - wasting and hairy.

Causes / Contributing factors

  • Contaminated or carrier incoming pigs.
  • Can be spread mechanically by equipment and visitors.
  • Water deprivation.
  • Low temperature and low humidity predisposes.
  • Stress / movement.
  • Nutritional changes.
  • Continual production.
  • High stocking densities.


This is based on herd history, clinical signs, post-mortem examinations including slaughter house checks and culture of the organism in the laboratory. The lesions in the lung are very characteristic. Serology can be used to identify different serotypes but the interpretation can be difficult because of cross reactions between serotypes.

App must be differentiated from enzootic pneumonia, PRRS, flu, and Salmonella choleraesuis pneumonia.

Further Reading

Click on the links below to find out more about this disease, including treatment, management control and prevention information. The top link is the main article on this disease.