Equine Influenza Influenza in the horse is a highly contagious viral disease that has many different strains, just as does the human flu. Usually younger horses are more seriously affected before they build up immunity. Influenza appears suddenly with a quick temperature rise, nasal and eye discharge, loss of appetite and dry coughing. The horses are usually depressed. A watery nasal discharge will later change to a thick yellowish type.
Fatalities are rare, but bacterial infections can follow.
Control must be primarily through isolation of new horses and a planned immunization program. An initial series of two doses about four weeks apart is needed to establish maximal immunization. Young race horses and show horses should be vaccinated every eight weeks for maximal protection against respiratory diseases. In horses that are not shown, an annual booster is likely sufficient. The resulting disease is an infection similar to the common cold in humans.