Equine Influenza

Equine influenza (EIV) is a virus that occurs sporadically in the horse population worldwide and is one of the most common infectious disease of the respiratory tract of horses. Certain subsets of the horse population are more susceptible to EIV, including young horses 1 to 5 years old and horses that have frequent contact with large numbers of horses.


Vaccination is a key method for controlling​ the spread of EIV. But in the case of unvaccinated horses, both vaccination and biosecurity should be used together. Modified live intranasal vaccines are recommended to achieve protection within 5 days of administration. Isolation of sick horses and extra precautions concerning hand washing and disinfecting of boots and clothing are also prudent. 

Clinic​​al Signs

Some signs that a horse may have EIV​ include:

  • Fever
  • Coughing
  • Nasal discharge
  • Leg swelling​

Diagnosis an​d Treatment

If you suspect that EIV is the cause of illness in your horses, call your veterinarian to have them examined. Definitive diagnosis can be determined using a variety of testing methods including virus isolation, PCR, immunoassay and serology. 

Human​​​ Health

There is no known human health impact caused by EIV.