Pet Columns, Office of Public Engagement, College of Veterinary Medicine at the University of Illinois at Urbana-Champaign

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Horse with Flu Feels Same as You

Pet Column for the week of November 27, 2000

Office of Public Engagement
2001 S. Lincoln Ave.
Urbana, Illinois 61802
Phone: 217/333-2907
By Carrie Gustavson
Information Specialist

"A horse with the flu will look and feel the same as a person with the flu," says Dr. Jonathan Foreman, equine veterinarian at the University of Illinois Veterinary Teaching Hospital in Urbana. Horses experience the same high fever, achy joints, stiff muscles, runny nose, cough, and lack of appetite that people do.

The culprit is the equine influenza virus -- a single-stranded RNA virus that probably came over from Europe in the 1940s. It's not contagious for humans, or any other species besides the horse. Virtually every species has its own species-specific flu virus.

Not only does the horse flu cause the same symptoms as the people flu, but it spreads in a similar fashion. "A cough can carry the virus 35 feet. So equine influenza will spread quickly through barns, especially if they are poorly ventilated," says Dr. Foreman. Horses that congregate at racetracks, shows, sales, or even veterinary hospitals are most likely to be exposed to the equine flu virus.

In the body, equine influenza infects the ciliated cells that line the respiratory tract. Cilia are the little arms coming out of a cell. Dust, debris, mucus, and bacteria that are breathed in are carried out of the respiratory tract and up to the throat by cilia -- kind of the way a crowd-surfer at a concert is moved along by the arms of fellow concertgoers. When viruses destroy the ciliated cells, it's easy for bacteria to take up residence there. "Without cilia, bacteria and mucus build up in the airways. That can allow bacteria to set in and multiply, leading to pneumonia," he says.

So if your horse has the flu, will chicken soup and bed-rest do the trick? "The key is rest," says Dr. Foreman. "Trainers don't like it, but it will take three weeks to repair the cilia. If a horse goes back to work before that, he can have additional problems." Besides complete stall rest for three weeks, your veterinarian may also prescribe a non-steroidal anti-inflammatory drug (NSAID) to make the horse feel better, reduce any fever, and keep his appetite up. Antibiotics won't help the horse get rid of a viral infection, but they may help if a secondary bacterial infection develops.

Equine influenza vaccines and human flu vaccines are subject to the same problems. The virus is a master of change, alternating the way it "looks" to the body so that, unlike the chicken pox, we can keep getting the flu year after year. For horses and for people, a completely effective vaccine is not available due to the rapidly changing nature of the virus. So for horses that have contact with other horses, Dr. Foreman recommends influenza vaccination every 60 to 90 days.

For more information about equine respiratory diseases and vaccinations, contact your local equine veterinarian.