This is one of the most common respiratory diseases in the horse. Highly contagious, the virus can be transmitted by aerosol from horse to horse over distances as far as 30 yards; for example, by snorting or coughing.
Signs to watch for are similar to those in a human with a cold; i.e., dry cough, nasal discharge, fever, depression, and loss of appetite. With proper care, most horses recover in about 10 days. Some, however, may show symptoms for weeks, especially if put back to work too soon.
Influenza is not only expensive to treat, but results in a lot of “down time” and indirect financial loss, not to mention discomfort to your horse. Unfortunately, influenza viruses constantly change in an effort to bypass the horse’s immune defense.