Editor’s note: This article has been updated to correct a factual error where ponies were incorrectly identified as horses. 

Eleven ponies at WSU contracted equine influenza, which is an airborne virus spread through infected droplets.

The ponies first started showing symptoms Aug. 21, including cough and fever. The animals have been symptom-free since Aug. 27, but the herd will be quarantined for two weeks after symptoms stopped as a precautionary measure, said Nina Woodford, director of WSU’s Office of the Campus Veterinarian. 

All 11 ponies are part of a U.S. Department of Agriculture research herd being used to study tick-borne diseases, Woodford said. The herd is in a closed facility, so they have not been exposed to other animals since May. No members of the general public have been exposed to the herd. 

The illness should not impact the herd’s ability to return to research, Woodford said. 

Horses can contract equine influenza from droplets on water buckets, feed racks, halters and people, she said. This makes it difficult to identify how the herd became infected. 

Woodford said the ponies were vaccinated for the virus in May. However, like human influenza, equine influenza can mutate rapidly and immunity from the vaccination can be relatively short-lived. Other horses at WSU were not exposed or infected.

Equine influenza is caused by a class of RNA-virus called an orthomyxovirus, which is unrelated to coronaviruses, according to a WSU press release. Equine influenza is not known to infect humans. 

Most horses recuperate quickly within about 21 days, according to the press release. 

This is the second outbreak of equine influenza in Whitman County in the last two weeks, Woodford said. The first outbreak was at a boarding facility, which is also quarantined.