equis - Articles
Lungworm infection
Synonym(s): Dictyocaulus, D. arnfieldi
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.
Presenting signs
- Chronic coughing.
Geographic incidence
- True prevalence unknown.
Pathogenesis
Etiology
- D. arnfieldi Dictyocaulus arnfieldi .
- Donkeys and tapirs are primary definitive hosts.
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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