Equis ISSN 2398-2977

Trichostrongylus axei

Contributor(s): Dwight Bowman, Grace Mulcahy

Introduction

Classification

Taxonomy

  • Superfamily:Trichostrongyloidea
  • Family:Trichostrongylidae.
  • Genus:Trichostrongylus
  • Species:axei.

Etymology

  • Gk:Tricho, hair.

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Clinical Effects

Epidemiology

Habitat

  • Environmental requirements of the free-living stages are relatively broad.
  • Found as a parasite of horses in diverse geographical regions.

Lifecycle

  • Egg. 
  • 1st stage larva. 
  • 2nd stage larva. 
  • 3rd stage (infective) larva. 
  • L4 and 5 in the mucosa of the host (may undergo hypobiosis).
  • Adult.

Transmission

  • By ingestion of infective eggs from contaminated pasture.  
  • AsT. axeialso infects ruminants and other animals mixed/rotational grazing with such species will not prevent infection of horses with this parasite, unlike most other nematodes of horses.

Pathological effects

  • Larval migration between the gastric glands is associated with inflammatory changes including hyperemia, eosinophila and mastocytosis.
  • Larval migration between the gastric glands eventually    →   cellular infiltration and hyperplasia, manifested grossly as plaque-like lesions on the gastric mucosa. 
  • These lesions may progress to become pedunculated.
  • Either on their own, or in combination with other gastrointestinal parasites,T. axeican cause protein-losing gastropathy, diarrhea and weight loss in the horse.

Other Host Effects

  • Small numbers ofT. axeiin the equine stomach are tolerated well, but histopathological changes can still be demonstrated in the gastric mucosa.

Control

Control via animal

  • Good management, nutrition and control of other infectious diseases.

Control via chemotherapies

  • All of the anti-nematode drugs licensed for horses are effective againstT. axei
  • Although drug resistance is not a widespread problem with this parasite, horses are likely to be infected with small strongyles also, hence the use of avermectins    Ivermectin   or pyrantel   Pyrantel  is suggested.

Control via environment

  • Good pasture management, ie pasture sweeping/manual removal of feces, is an aid to control. 
  • The lack of host-specificity ofT. axeilimits the effectiveness of this means of control.

Diagnosis

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Proudman C J (1999) The role of 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 (6), 711-724 (good analysis of the prevalence of various small strongyle species) PubMed
  • Callinan A P L (1978) The ecology of the free-living stages of Trichostrongylus axei. Int J Parasitol 8, 453-456.

Other sources of information

  • Soulsby E J L (1982) Helminths, Arthropods and Protozoa of Domesticated Animals. Balliere & Tindall, UK. pp 178-180. ISBN: 0 7020 0820 6 (a general comprehensive reference book).

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