Equis ISSN 2398-2977

Lungworm infection

Synonym(s): Dictyocaulus, D. arnfieldi

Contributor(s): Sheelagh Lloyd, Timothy Mair, Vetstream Ltd

Introduction

  • Cause:Dictyocaulus arnfieldi  Dictyocaulus arnfieldi  - occasional cause of parasitic bronchitis in horses co-grazing with donkeys.
  • Signs: chronic cough especially during exercise; poor condition.
  • Rarely causes clinical signs in donkeys.
  • Diagnosis: recovery ofD. arnfieldilarvae from feces   Feces: parasitology  or endoscopy   Respiratory: endoscopy  /tracheal wash   Trachea: tracheal wash  .
  • Treatment:
    • USA: ivermectin, mebendazole.
    • UK: ivermectin, menbendazole, thiabendazole, fenbendazole, levamisole.
  • Prognosis: good.
Print off the Owner factsheet on Respiratory problems in your horse to give to your clients.

Pathogenesis

Etiology

Predisposing factors

General
  • Shared grazing with donkeys.
  • Horses, particularly young horses, can occasionally produce patent infections and pass the infection themselves.
  • Poor parasite control program   Parasite control programs  .

Pathophysiology

  • Sharing of pasture between donkeys and horses.
  • Infection at pasture (larvae ingested)    →   larvae infiltrate alveoli   →   lymphoid cell cuffing around airways   →   low grade inflammation   →   bronchitis.
  • Infection withD. arnfieldi  →   adult worms in bronchi   →   bronchial epithelial hyperplasia and increase in size and number of goblet cells.
  • Wide cuffs of lymphoid cells around the airways seen microscopically.
  • Eosinophilic response and exudate.

Timecourse

  • Prepatent period minimum 2 months.

Epidemiology

  • Lifecycle similar toD. viviparusin cattle.
  • Adult worms in small bronchi.
  • Larvae in eggs passed in feces hatch almost immediately to first stage larvae.
  • Develops to L3 in summer months.
  • Larvae can survive on pasture for 6-7 weeks under suitable conditions (damp/shade).
  • Pre-patent period minimum 2 months.
  • Infections in older horses rarely become patent - larval development usually becomes arrested and egg-laying adults do not arise.

Diagnosis

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Treatment

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Prevention

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Outcomes

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Further Reading

Publications

Refereed papers


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