Actinobacillosis is caused by a systemic bacteria that affects many farms that have high health issues causing arthritis, pneumonia, or skin discoloration in animals of all ages.

Alternative names: Actinobacillus suis, Actinobacillus equuli


It is mainly caused by the bacterium called Actinobacillus suis and in rare occasions by Actinobacillus equuli. The first of these is present in most farms and lives in the tonsils of older pigs, especially in sows.




  • Skin discoloration.
  • Abortion. 
  • Pneumonia.
  • Septicemia.

Lactating piglets

  • Sudden death.
  • High fever.
  • Pneumonia.
  • Skin discoloration.
  • Skin lesions (not to be confused with erysipelas).
  • Arthritis.
  • Lameness.
  • Septicemia.

Weaners and growers

  • Rarely seen.
  • The same as in piglets.


Causes / Contributing Factors

  • It can be triggered by PRRS.
  • It can infect the pig through the respiratory system or through cuts or abrasions.
  • It gets multiplied in blood (occasionally) and it can be found in various parts of the body, especially in lungs and joints; multiple small abscesses are produced here. 



Laboratory and post-mortem tests to demonstrate characteristic lesions and the presence of the organism.



  • The organism is sensitive to antibiotics but most particularly to amoxicillin or ampicillin.
  • In persistent outbreaks, when it is possible to predict its occurrence, you should take preventative measures such as injecting long-lasting antibiotics to all litters or add medication to the water.
  • In problematic cases, give penicillin via feed to sows during the first 3 weeks after birth; this has demonstrated to be useful.

Atlas of pathology

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