Equis ISSN 2398-2977

Triodontophorus spp

Contributor(s): Dwight Bowman, Sheelagh Lloyd, Grace Mulcahy




  • Phylum:Nematoda.
  • Superfamily:Strongyloidea.
  • Family:Strongylidae.
  • Genus:Triodontophorus.
  • Species:serratus,brevicauda,minor,tenuicollis,nipponicus.
  • CraterostomumandEsophagodontusspp also closely related.


  • Triodontophorus: Gk trio three; dontophorus toothed.

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Clinical Effects




  • Egg.
  • 1st stage larva.
  • 2nd stage larva.
  • 3rd stage larva (infective stage).
  • 4th stage larva.
  • Immature and mature adults.


  • By ingestion of infective larvae (L3) on pasture.
  • Infective larvae on pasture may come from eggs deposited in previous or current grazing season.

Pathological effects

  • Triodontophousspp are normally found as part of mixed infections.
  • Response is likely to be a typical response to gastrointestinal helminths involving eosinophils, mast cells, and immediate-type hypersensitivity reactions.
  • Generally pathology is considered as part of the general syndrome of equine strongylosis.
  • Plug-feeding by adult worms causes erosions in the mucosa of the large intestine.
  • Chronically, untreated infections are associated with diarrhea, anemia and possibly colic.
  • Adults ofT. tenuicollisfeed in a synchronized manner in herds in the same region of the mucosa, and hence cause larger erosions than other spp   Triodontophorus: ulcers 01    Triodontophorus: ulcers 02  .

Other Host Effects

  • As with other strongyles of horses, low burdens are not pathogenic.
  • Factors which increase infection pressures, such as high stocking rates, permanent horse pastures, can   →   higher, pathogenic, burdens.


Control via animal

Control via chemotherapies

Control via environment

Pasture management
  • Removal of feces up to twice weekly (weekly can suffice in temperate climates).
  • Avoid high stocking densities.
  • Rotational/mixed grazing.


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Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Molento M B, Antunes J, Bentes R N & Coles G C (2008) Anthelmintic resistant nematodes in Brazilian horses. Vet Rec 162 (12), 384-385 PubMed.
  • Proudman C J (1999) The role in parasites in equine colic. Equine Vet Educ 11 (4), 219-224.
  • Bucknell D G, Gasser R B & Beveridge I (1995) The prevalence and epidemiology of gastrointestinal parasites of horses in Victoria, Australia. Int J Parasitol 25, 711-724 (Provides a useful description of the occurrence of Triodontophorus spp, compared with that of other strongyles, in horses of this region) PubMed.
  • Lichtenfels J R (1975) Helminths of domestic equids. Illustrated keys to genera and species with emphasis on North American forms. Proc Helminthol Soc Washington 42 165-170 VetMedResource (The standard key used by most investigators studying strongyles of horses).

Other sources of information

  • Bowman D D et al (1999) Georgis' Parasitology for Veterinarians. 7th edn. W B Saunders Co, USA. ISBN: 0 7216 7097 0 (a useful set of photographs for identification of equine strongyles).