Equine Influenza Reported Nasal discharge is one symptom of Equine Influenza.

Equine Influenza Reported in Oregon Horses after Show

Samples from three Oregon horses that were among a group of ailing equines confirm the affected are positive for Equine Influenza A Virus. The horses were at the Far West Championship Show at the Deschutes County Fairgrounds where the illness first became apparent.
Veterinarians from Bend Equine Medical Center were involved with treating and diagnosing the outbreak at the horse show that started with 15 affected horses. Symptoms included fevers, coughing, nasal discharge, and lethargy. All of the horses are recovering with symptomatic treatment, although the number of cases has risen to more than 20, at last count.
The horses’ samples were negative for Equine Herpes Virus (EHV-1), EHV-4 and for Equine Viral Arteritis.
Veterinarians state the Equine Influenza Virus can persist in the environment and on inanimate objects for about two to three days. Infected horses should be quarantined for 21 days and any exposed, but non-symptomatic horses can be quarantined for 14 days. The virus is very contagious and can travel up to 50 yards through the air.
Infected horses should be rested from work for one week for every day of fever they experience. Not doing so poses a risk of cardiac muscle damage, according to vets.
Intranasal vaccines will provide the most rapid protection, usually by day 5, against influenza. Intramuscular influenza vaccines are effective as well, but take about two weeks to provide protection.
Ask your veterinarian if the vaccine they give carries the more recent strains (A2/Clade 1/North American).