This highly contagious virus is a newly emerging respiratory pathogen in dogs and causes a clinical syndrome that mimics “kennel cough.” Canine influenza virus infections are frequently mistaken for infections due to the Bordetella bronchiseptica/ parainfluenza virus complex . 

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Recent media attention to canine influenza has alarmed dog owners. As with any emerging disease, new information is learned about canine influenza each day. The University of Illinois College of Veterinary Medicine has assembled these quick facts to address the concerns of area dog owners.
  • A new influenza strain was first reported in January 2004 at a Florida greyhound track.

  • The virus was first identified in the pet population in spring 2005, when the University of Florida College of Veterinary Medicine isolated and identified a strain of the influenza virus as a cause of a serious respiratory illness in dogs in shelters, humane societies, boarding facilities, and veterinary hospitals in that state. 

  • This virus, belonging to the influenza A family, is a mutated strain of an equine influenza virus that has been detected in horses for over 40 years.

  • This specific strain of influenza is not known to infect humans or poultry.

  • As of October 7, 2005, 2:00 p.m., (Eastern) confirmed positive sero samples of canine influenza had been diagnosed in the pet populations in ten states: Florida, New York, California, Oregon, Washington, New Jersey, Connecticut, Massachusetts, Ohio, and Pennsylvania. It had also been diagnosed in Washington, D.C.

  • As of October 7, 2005, there had been no reported cases of canine influenza in the State of Illinois.

Signs and Virulence

  • Canine influenza is a new, contagious respiratory disease that may mirror signs of kennel cough, including sneezing, coughing, and fever. It requires veterinary medical attention.

  • Nearly 100 percent of dogs that come in contact with the virus become infected, regardless of age or vaccination history. Of those infected, 20 percent show no signs of disease.

  • Of the 80 percent that exhibit signs, two forms have been observed:

  • Mild infection. Symptoms include a low-grade fever, nasal discharge, and a persistent cough that could last up to three weeks.

  • Severe infection. Symptoms include a high fever, increased respiratory rates with difficulty breathing, and other indications of pneumonia.

  • Researchers have observed canine influenza to be fatal in fewer than 8 percent of infected patients.

  • Because this virus is new to dogs, most dogs will not have a natural immunity to the influenza.


  • Contact your veterinarian if you believe your dog may have contracted canine influenza. Your veterinarian is best qualified and equipped to make a diagnosis and to provide advice for caring for any symptom-free dogs you may have in your household.

  • Although most dogs will recover from this virus without any treatment, dogs exhibiting symptoms of a mild infection can be treated with antibiotics to prevent secondary bacterial infections.

  • Others with a more severe form of the virus require the same treatment as humans with influenza: fluids and rest, and more severe cases requiring intravenous fluids and antibiotics. Treatment for this population has been successful in about 95 percent of the cases.

Spread of the Virus

  • Canine influenza is thought to be a mainly airborne virus, most likely transmitted by an infected dog sneezing or coughing on another.

  • Symptoms generally appear two to five days after a dog is exposed to the virus.

  • Infected dogs have the ability to spread the virus for seven to ten days from the onset of symptoms.

  • Much the same as human influenza, this virus can be spread through direct contact with a contaminated surface. 

  • Infected dogs may not exhibit signs of infection, but are still able to spread the virus.


  • Although researchers are working on a vaccine to prevent canine influenza, one does not exist at this time.

  • As with any other potentially communicable disease, exercising a few common-sense precautions can help to prevent the spread of canine influenza:

  • Use kennels, grooming facilities, and dog parks that are well known to you.

  • Watch for news of canine influenza outbreaks in your area.

  • Contact facilities in advance to ask about any recent occurrences of respiratory illnesses in dogs.

  • Inquire about steps pet facility operators take to isolate any apparent cases of illness.

  • If your pet is exhibiting symptoms of canine influenza, contact your local veterinarian. Your veterinarian is best qualified and equipped to make a diagnosis.

  • If your pet has a respiratory infection or has recently recovered from one, limit its contact with other dogs for a couple of weeks, allowing for complete recovery and reducing the likelihood of transmission.

  • Assume that the more exposure your dog has to other dogs, the greater the chance of becoming infected.

Transmission to Humans

  • There is no evidence of canine influenza spreading to humans.

  • The equine strain of influenza has been in horses for over 40 years without any reported human infection.

The Bottom Line

"The important thing is that people not panic over this. Canine flu is a new disease, so there is a lot we don't know about it, but the mortality rate is very low, and many dogs don't even get sick from it. It made a huge splash in the press because the molecular genetics part of the story established such a clear cross-species transmission of an influenza virus-not because it is a new, deadly disease of dogs. The virulence of this virus has been greatly exaggerated by some."
-Dr. Tom Graves, University of Illinois College of Veterinary Medicine


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