Metastrongylus

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Lungworms of Pigs

METASTRONGYLUS species

  • Found in the bronchioles and smaller bronchi.
  • Three species, but these are all very similar.
  • Look like the Dictyocaulus species in ruminants and produce similar pathology.
  • Very pathogenic and can cause severe lung damage.
  • Even low level infections will check growth.
  • Immunity develops quickly.
  • Larvated eggs with a wavy outline passed in faeces.
  • Intermediate host is the earthworm, therefore this only affects outdoor pigs.
  • Becoming more common with the trend towards free-range husbandry.
  • Infection occurs when the earthworm is eaten.
  • Larvae migrate via the mesenteric lymph nodes to the lungs.


  • Found in bronchioles and smaller bronchi
  • Grossly:
    • Small grey nodules, especially along ventral border of caudal lobes
    • Adult worms in bronchi and bronchioles
  • Histologically:
    • Catarrhal and eosinophilic bronchitis and bronchiolitis
    • Possibly atelectasis
  • Rarely becomes extensive
  • May transmit swine influenza