Friday, 5 February 2016

All About - African Horse Sickness



What is African Horse Sickness?

So far there has never been an outbreak of this disease in Great Britain.  It cannot be directly spread between horses but it is carried  by midges!  It is a notifiable disease and is highly infectious and deadly.  It affects horses, mules, donkeys and zebra and is generally seen (as the name suggests) in Africa.  




The disease has been seen in the Middle East and India but more recently in Spain and Portugal. There has been increased concern that the midges are moving northwards due to the appearance of Bluetongue (affecting sheep) in Great Britain in  2007 which is also carried by midges!  Continuing climate change could mean this disease could be seen in Great Britain.  There are 3 forms of the virus; the acute lung form, the cardiac or heart form and a mix of both. 


Signs

These may include:

  • Swelling of the eyelids, face, neck or  head (heart form) 
  • Unable to swallow (heart form) 
  • Redness around the conjunctiva of the eyes (lung form) 
  • Discharge and frothing from the nostrils (lung form) 
  • Raised temperature (lung and heart forms) 
  • Difficulty breathing and dilated nostrils (lung and heart forms to differing extent) 
  • Sweating (lung form) 
  • Heave lines because of breathing difficulties (lung form) 
  • Coughing 
  • Depression 
  • Colic (heart form) 
  • Bleeding from membranes of eyes and mouth in latter stages (heart form)



Horses with the mixed form of the virus will show mild respiratory signs and the swellings seen in the heart form.  90% of infected horses with the lung (acute) form will usually die within 24 hours, 50 – 70% of mules will die but only 10% of donkeys.  The heart form has a lower death rate of 50%, the mixed form 70%.


Causes

African Horse Sickness is caused by a virus which is carried by midges – Culicoides imicola.  These midges (similar to those which cause sweet itch) like warm and humid conditions so cold and long winters will usually halt any spread.  The female midge bites a horse and transfers the virus.  Although, the virus cannot be spread directly from horse to horse the midge could bite more than one horse or if it bites an infected horse and then bites another it will transfer the virus. 


Diagnosis

Call the vet.  The signs noted above usually assist the initial diagnosis.  Several tests can be used once a horse has died to confirm the diagnosis.  Unfortunately the immune response is not usually quick enough for the animal to recover.





Treatment

There is no treatment available at the moment.


Prevention

Good biosecurity procedures, for example quarantine measures, hygiene and cleanliness are vital – I wrote a blog about this.  There is a vaccine available for use in Africa but this is not licensed for use in Europe as a whole or Great Britain.  This is because it is a live vaccine and therefore has the chance of causing an outbreak!  Research is ongoing with a dead virus.

 
Obviously, if an outbreak were to occur the same measures which can be used to prevent midges biting and causing sweet itch may reduce the chance of your horse becoming infected.


This disease is horrible and luckily is not seen in this country, hopefully a good vaccine will have been developed before the midges ever get near us! 

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Until next time!
Jo

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