Equine adenovirus infection (EAI)

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  • Widespread infection caused by Equine adenovirus (EAV)    .
  • Incidence : subclinical: widespread in normal foals; acute: immunodeficient foals (especially Arabian).
  • Signs : usually subclinical; mild upper respiratory tract (URT) disease in normal foals; immunodeficiency    may   →   severe interstitial pneumonia   →   death.
  • Diagnosis : virus isolation.
  • Treatment : usually unnecessary; symptomatic.
  • Prognosis : good except in Arabian foals with SCID syndrome  [Immunology: combined immunodeficiency]  when grave.
    Print-off Owner factsheet on Respiratory problems in your horse - not a good wheeze! to give to your client   


Differential diagnosis


Clinical signs

Most horses
  • Mild URT infection.
  • Cough.
  • Conjunctivitis.
  • Fever - mild and transient.
  • Diarrhea.
  • Mild bilateral nasal discharge.

Arab foals
  • Severe interstitial and bronchopneumonia with muffled normal airway sounds and extensive adventitious noises.
  • Cough.
  • Ocular/nasal discharge.
  • Fever.
  • Ulcerated oral mucosa.
  • Diarrhea.



  • Generally: good.
  • Arab foals with SCID: grave.
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