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The prepatent period is 2-3 months.
 
The prepatent period is 2-3 months.
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==== Epidemiology ====
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*Main source of infection = donkeys (remain infected for years) - contaminate horse pasture.
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*Infection can cycle in horses.
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{| style="width:75%; height:200px" border="1"
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!
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!'''Horses'''
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!'''[[Lungworm - Donkey|Donkeys]]'''
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|-
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|'''Prevalence'''
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|10-20% 
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|75%
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|-
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|'''Adult worms'''
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|Few
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|Many
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|-
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|'''Eggs in faeces'''
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|Often zero
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|Many
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|-
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|'''Period of patency'''
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|<8months
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|5+ years
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|-
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|'''Clinical signs'''
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|Sometimes
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|Rarely
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|}
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'''NOTE''': Clinical signs - chronic cough at rest or during exercise, single animal or group of horses, autumn or early winter.
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*''Dictyocaulus arnfieldi'' causes [[Respiratory Parasitic Infections - Pathology#Dictyocaulus arnfieldi|cough in horses]]
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==== Pathogenicity ====
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*Raised areas of over-inflated pulmonary tissue (several cms in diameter) surrounding small bronchus containing worms and mucopurulent exudate.
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*Hyperplastic bronchial epithelium.
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*Peribronchial "cuffing".
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==== Diagnosis ====
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*Clinical signs.
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*Grazing history (donkey contact or shared grazing).
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*Faecal examination (only detects patent infections = small proportion of lungworm infections in horses):
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**process sample immediately = McMaster method, embryonated eggs
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**process sample later = Baerman technique, larvae with tail spine.
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*Tracheobronchial washings (large eosinophils).
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*Response to anthelmintic treatment (e.g. resolution of clinical signs = retrospective diagnosis).
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==== Control ====
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*Do not keep horses on pastures grazed by donkeys (potential carriers).
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*Treat donkeys with appropriate anthelmintic in spring if grazed with horses.
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*Found in smaller [[Bronchi and Bronchioles Inflammatory - Pathology#Infectious causes of bronchitis or bronchiolitis|bronchi]]
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*Cause of chronic cough
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*Donkeys are a reservoir mostly without any clinical signs
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*Gross pathology:
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**Raised areas of over-inflated pulmonary tissue surrounding small bronchus, containing worms and mucopurulent exudate
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**Hyperplastic bronchial epithelium
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**Coiled worms in small bronchi
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**Peribronchial cuffing
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**In caudal lung lobes
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*Histologically
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**Central coiled parasites and associated chronic catharral bronchitis
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**Goblet cell hyperplasia
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**Lymphoid cell infiltration
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*In [[Hindgut Fermenters - Horse - Anatomy & Physiology|horses]], the worms usually fail to achieve sexual maturity
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[[Category:Trichostrongyloidea]][[Category:Horse_Nematodes]]
 
[[Category:Trichostrongyloidea]][[Category:Horse_Nematodes]]
 
[[Category:To_Do_-_Max]]
 
[[Category:To_Do_-_Max]]
 
[[Category:Respiratory Parasitic Infections]]
 
[[Category:Respiratory Parasitic Infections]]
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