Difference between revisions of "Dictyocaulosis - Horse"

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==== Epidemiology ====
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== Introduction  ==
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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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''[[Dictyocaulus arnfieldi]]'' is the lungworm of horses. The main source of infection are donkeys as these remain infected for years and contaminate horses' pasture. Infection can cycle in horses.
 
  
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The prevalence of lungworm in horses is around 10-20% whereas in donkeys it is 75%. There are very few adult worms or eggs in the faeces in horses, whereas in donkeys there are many of both present. In horses, the period of patency is around 8 months or less, whereas in donkeys it is around 5 years, hence such a problem occurs when donkeys share pasture with horses. Also, clinical signs are rarely seen in donkeys, unlike horses where signs can be much more severe.
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{| style="width:75%; height:200px" border="1"
  
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== Clinical Signs  ==
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!
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!'''Horses'''
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!'''[[Lungworm - Donkey|Donkeys]]'''
  
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Clinical signs vary from none to chronic and include a chronic cough at rest or during exercise in a single animal or in a group of horses. This is most prevalent in autumn or early winter.
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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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== Diagnosis  ==
 
  
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Clinical signs and time of year can be indicative of the disease. History is very important and information such as has co-grazing with donkeys is very important.  
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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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Faecal examination can be used but this only detects patent infections, which account for only a small proportion of lungworm infections in horses. The sample must be processed immediately using the McMaster method to search for embryonated eggs. OR the sample can be processed at a later date and the Baerman technique can be used to detect larvae with tail spine.
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*''Dictyocaulus arnfieldi'' causes [[Respiratory Parasitic Infections - Pathology#Dictyocaulus arnfieldi|cough in horses]]
  
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Tracheobronchial washings can be useful and will show large eosinophil count.  
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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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Response to anthelmintic treatment by resolution of clinical signs will provide a retrospective diagnosis.  
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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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== Treatment and Control ==
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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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Do not keep horses on pastures grazed by donkeys as these are potential carriers. Treat donkeys with appropriate anthelmintic in spring if grazed with horses. If horses are found to have the disease then treatment with an appropriate anthelmintic is required. If the condition is very severe then supportive treatment with brochodilators may be required.
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*Found in smaller [[Bronchitis#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 [[Equine Alimentary System  - Anatomy & Physiology|horses]], the worms usually fail to achieve sexual maturity
  
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== References ==
 
  
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Bertone, J. (2006) '''Equine Geriatric Medicine and Surgery,''''' Elsevier''
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[[Category:Respiratory Diseases - Horse]]
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[[Category:Respiratory Parasitic Infections]]
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Blood, D.C. and Studdert, V. P. (1999) '''Saunders Comprehensive Veterinary Dictionary '''(2nd Edition) ''Elsevier Science''
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[[Category:Bronchi and Bronchioles - Pathology]]
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[[Category:To Do - Clinical]]
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Brown, C.M, Bertone, J.J. (2002) '''The 5-Minute Veterinary Consult- Equine''''', Lippincott, Williams & Wilkins ''
 
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Cowart, R.P. and Casteel, S.W. (2001) '''An Outline of Swine diseases: a handbook '''''Wiley-Blackwell''
 
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Merck & Co (2008) '''The Merck Veterinary Manual '''(Eighth Edition) ''Merial''
 
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Reed, S.M, Bayly, W.M. and Sellon, D.C (2010) '''Equine Internal Medicine '''(Third Edition), ''Saunders. ''
 
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{{review}}
 
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{{OpenPages}}
 
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[[Category:Respiratory_Diseases_-_Horse]] [[Category:Respiratory_Parasitic_Infections]] [[Category:Bronchi_and_Bronchioles_-_Pathology]] [[Category:Expert_Review - Horse]]
 

Revision as of 16:31, 19 February 2011

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
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