Canis ISSN: 2398-2942

Oslerus (Filaroides) osleri

Synonym(s): O.osleri

Contributor(s): Stephen Barr




  • Superfamily: Metastrongyloidea.
  • Genus: Filaroides.

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Clinical Effects



  • Adults in fibrous nodules at bifurcation of the trachea and in adjacent bronchi of dogs, foxes and other Canidae Oslerus osleri tracheal nodules 02.


  • See lifecycle diagram Lifecycle Oslerus osleri - diagram :
    • First stage larva.
    • Adult.


  • Transmission from bitch to pups - L1 in respiratory secretions is carried out of the mouth with partly digested food that is being regurgitated to feed the pups.
  • Transmission to other dogs - L1 passed in the feces or vomitus is fully infective if these are eaten relatively fresh.

Pathological effects

  • Worms reside in cavity of fibrous granuloma, usually less than 1-2 cm in diameter.
  • Nodules (1-2 mm) first seen at 2-3 months and grow slowly over a year or more.
  • Nodules grayish white to pink, usually polypoid or sessile, firmly attached to tracheal wall, occasionally hemorrhagic and wart-like.


Control via animal

  • Anthelmintic treatment not always fully effective.
  • Isolation of infected dogs.
  • Separation of dogs so they have no access to fresh feces or vomitus.
  • Anthelmintic treatment of bitch before whelping and during lactation.
  • Deliver puppies by Cesarian section and rear them in separate kennels to eliminate parasite.

Control via chemotherapies

  • Fenbendazole Fenbendazole licenced use: 50 mg/kg/day for 7 days.
  • Oxyfendazole - 10 mg/kg/day for 14 days.

Control via environment

  • Removal of all feces immediately when passed.
  • Isolation of infected dogs.
  • Desiccation will kill the larvae.


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Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Bourdoiseau G, Cador√© J L, Fournier C et al (1994) Canine oslerosis: update on diagnosis and treatment. Parasite (4), 369-378 VetMedResource.