African Horse Sickness

What is African Horse Sickness? 

African Horse Sickness is a serious often fatal disease of horses, mules and donkeys. The virus is spread by infected insects and causes fever and respiratory problems in affected horses. Death is common and can occur suddenly in horses that are infected with African Horse Sickness. Currently African Horse Sickness is not endemic in the western hemisphere and is considered a foreign animal disease in the United States.

Clinical Signs: There are four manifestations of African Horse Sickness:

  1. Pulmonary Form
    1. Acute to preacute form of the disease affecting the lungs 
    2. Fever, accompanied with depression, profuse sweating, inflammation of conjunctivae difficulty breathing, coughing copious frothy discharge from the nostrils. 
  2. Cardiac Form 
    1. Subacute form of the disease affecting the heart
    2. Fever, depression, swelling around the eyes, small hemorrhages and conjunctival swelling 
    3. Fluid swelling of the head 
    4. Fluid Swelling extending down the neck towards the chest 
    5. Dysfunction of the upper airways and esophagus 
  3. Mixed Form 
    1. Combination of lunch and cardiac forms of the disease 
    2. Initial evidence of pulmonary involvement followed by face and body swelling 
    3. Acute bouts of coughing
  4. African Horse Fever Sickness 
    1. Mildest form of the disease 
    2. Moderate malaise, fever lasting several days, poor appetite, depression, occasionally mild conjunctivitis, dyspneal and swelling of the supraorbital fossa. 

Diagnosis: In the early febrile phase of African Horse Sickness, it is impossible to distinguish from other diseases causing fever. A presumptive diagnosis is only feasible following development of the characteristics clinical signs. Submission of a blood test for the virus is essential to confirm the disease. 

Treatment: There is no specific treatment for African Horse Sickness, other than supportive care. 

Prevention: Control of the biting midges is best for control. A vaccine is available in endemic areas.