Difference between revisions of "Dictyocaulus arnfieldi"

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[[Category:Trichostrongyloidea]][[Category:Horse_Nematodes]]
 
[[Category:Trichostrongyloidea]][[Category:Horse_Nematodes]]
[[Category:To_Do_-_Parasites]]
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[[Category:To_Do_-_Max]]
 
[[Category:Respiratory Parasitic Infections]]
 
[[Category:Respiratory Parasitic Infections]]

Revision as of 19:32, 20 July 2010

Lungworm

DICTYOCAULUS ARNFIELDI

Dictyocaulus arnfieldi from horse faeces - Joaquim Castellà Veterinary Parasitology Universitat Autònoma de Barcelona

General

  • Lungworm of equidae; adult worms found in smaller bronchi. Frequently incriminated as the cause of a chronic cough.

Morphology and Life-Cycle

  • Similar to lungworm in cattle, except:
    • embryonated eggs (80-100µm) passed in fresh faeces; and
    • prepatent period = 12weeks.

Epidemiology

  • Main source of infection = donkeys (remain infected for years) - contaminate horse pasture.
  • Infection can cycle in horses.


Horses Donkeys
Prevalence 10-20% 75%
Adult worms Few Many
Eggs in faeces Often zero Many
Period of patency <8months 5+ years
Clinical signs Sometimes Rarely


NOTE: Clinical signs - chronic cough at rest or during exercise, single animal or group of horses, autumn or early winter.

Pathogenicity

  • Raised areas of over-inflated pulmonary tissue (several cms in diameter) surrounding small bronchus containing worms and mucopurulent exudate.
  • Hyperplastic bronchial epithelium.
  • Peribronchial "cuffing".

Diagnosis

  • Clinical signs.
  • Grazing history (donkey contact or shared grazing).
  • Faecal examination (only detects patent infections = small proportion of lungworm infections in horses):
    • process sample immediately = McMaster method, embryonated eggs
    • process sample later = Baerman technique, larvae with tail spine.
  • Tracheobronchial washings (large eosinophils).
  • Response to anthelmintic treatment (e.g. resolution of clinical signs = retrospective diagnosis).

Control

  • Do not keep horses on pastures grazed by donkeys (potential carriers).
  • Treat donkeys with appropriate anthelmintic in spring if grazed with horses.
  • Found in smaller bronchi
  • Cause of chronic cough
  • Donkeys are a reservoir mostly without any clinical signs
  • Gross pathology:
    • Raised areas of over-inflated pulmonary tissue surrounding small bronchus, containing worms and mucopurulent exudate
    • Hyperplastic bronchial epithelium
    • Coiled worms in small bronchi
    • Peribronchial cuffing
    • In caudal lung lobes
  • Histologically
    • Central coiled parasites and associated chronic catharral bronchitis
    • Goblet cell hyperplasia
    • Lymphoid cell infiltration
  • In horses, the worms usually fail to achieve sexual maturity