Ask the Vet with Dr. Sally DeNotta

Q:  I hear that 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, 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 on people’s hands, grooming tools, and communal surfaces. Horses with flu develop fever (temp > 101.5 F), cough, and crusty nasal discharge.  Some will also show signs of generalize illness, such as reduced appetite and lethargy. Nearly all infected horses will recover from flu, but it can take weeks to months for their respiratory system to fully heal after infection.

Equine influenza is preventable with vaccination and is considered a “Risk-Based Vaccine” by the American Association of Equine Practitioners. This means that horse owners should discuss with their veterinarians whether the flu vaccine is right for their horse.  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 are coming and going.  It is also usually a good idea to vaccinate all young horses for flu, as they tend to be more susceptible to developing more severe signs of illness when infected.

So, what should you do to protect your horse?  First of all, make sure he is up to date on his annual vaccinations.  This is also especially important here in Florida, where mosquito season—  and the spread of diseases such as Eastern equine encephalitis,  and West Nile virus — begins early! If your barn is experiencing an outbreak of flu, talk to your veterinarian about administered 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.  Further information can be found on the Equine Disease Communication Center website:  Equine Influenza Owner Factsheet


Dr. Sally DeNotta is also a clinical assistant professor in large animal internal medicine and the University of Florida’s equine veterinary extension specialist.

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