Equine Flu Season Steps for Horse Owners

Here’s how to protect your horse from this highly contagious respiratory virus.
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Nasal swab test for influenza
PCR testing of nasal swabs is the recommended method for diagnosing equine influenza. | Courtesy University of Florida

Q. I hear that the equine flu is going around right now. Should I be worried? How can I protect my horses?

A. Great question! And, yes, it is indeed flu season for horses. Equine influenza (EI), or “flu,” is a highly contagious respiratory virus that can affect horses of all ages. Similar to flu in people, transmission occurs through direct contact (especially nose to nose) and inhalation of aerosolized respiratory droplets from coughing horses. It can also be transmitted via people’s hands, grooming tools, and contact with communal surfaces. Horses with flu develop fever (a temperature of at least 101.5 degrees F), cough, and crusty nasal discharge. Some also show signs of generalized illness (e.g., reduced appetite, lethargy). Nearly all infected horses recover from flu, but it can take weeks to months for their respiratory systems to fully heal after infection.

Equine influenza is preventable with a vaccination that’s considered a risk-based vaccine by the American Association of Equine Practitioners (AAEP). This means horse owners should discuss with their veterinarians whether the flu vaccine is right for their horses. It is generally recommended for any horse coming into contact with new horses—whether that be through travel on and off the property or by living in a barn where other horses come and go. It is also usually a good idea to vaccinate all young horses for flu, as they tend to be more susceptible to developing severe signs of illness when infected.

So, what should you do to protect your horse? First, make sure he is up to date on his annual vaccinations. This is especially important here where I’m located in Florida, where mosquito season—and the spread of diseases such as Eastern equine encephalomyelitis (EEE) and West Nile virus (WNV)—begins early. If your barn is experiencing an outbreak of flu, talk to your veterinarian about administering an intranasal flu booster to the horses that have not yet shown any signs of illness. This vaccine can provide immunity in as little as five days and is one of the few vaccines recommended for use in the face of an outbreak. Finally, whenever traveling with your horse, take his temperature twice daily and watch closely for signs of coughing, reduced appetite, or general illness. As always, report any abnormal observations to your veterinarian.


Written by:

SallyAnne L. DeNotta, DVM, PhD, Dipl. ACVIM, is a clinical assistant professor and equine veterinary extension specialist at the University of Florida’s College of Veterinary Medicine, in Gainesville.

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