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Dog Flu / Canine Influenza

Dog Flu or Canine Influenza can be caused by two different and unrelated canine influenza viruses (H3N2 and H3N8). Canine influenza virus H3N8 was first reported in Flroida during 2003, and canine influenza virus H3N2 emerged in Chicago during March 2015. Due to the fact that dogs have no natural immunity to these viruses as they are relatively new, in less than 6 months, the H3N2 strain spread to nearly half of the continental states. 

canine influenza dog flu how long contagiousDog Flu is a highly contagious respiratory disease. Unless a dog has already had the illness and recovered or has been vaccinated, almost every dog exposed to the virus will become infected. The clinical signs of canine influenza virus infection usually begin less than 5 days after infection. Approximately 80% of dogs, exposed to canine influenza develop clinical disease, with most of these having a mild disease course of disease. A subset of about 10 to 20% of dogs develop subclinical infection, but can still shed the virus and transmit disease to other dogs. Up to 5-8% of dogs may progress to a more severe form of the condition – including fatalities; puppies and older dogs were at higher risk of more severe disease.  The symptoms of Dog Flu or Canine Influenza are very similar to those of other canine infectious respiratory disease pathogens and thus cannot be distinguished from these other causes of acute respiratory disease based on clinical signs alone. Testing can be performed to confirm a diagnosis of CIV infection; however, samples must be sent to a lab, so this diagnostic test does not help acute management.

There is no specific treatment for Dog Flu and treatment is generally supportive therapy. Intravenous fluids and and/or antibiotics may be indicated.

In October 2016, Merck Animal Health developed and licensed the first bivalent flu vaccine against H3N2 and H3N8. This vaccine aids in the control of disease associated with Canine Influenza Virus H3N8 and H3N2 infection.

Similarities Between the H3N2 and H3N8 Viruses

  • Highly infectious
  • Spread by direct contact with infectious respiratory secretions or by indirect contact with fomites (kennel surfaces, bowls, etc.) or people carrying the virus on hands and clothes.
  • Can result in hemorrhagic pneumonia
  • High morbidity, relative low mortality

Why the Dog Flu Outbreak During March of 2015 in Chicago was Unprecedented and Devastating

  • Dogs have no natural immunity to Dog Flu because it is a newer virus.
  • This virus is easily spread by mobile dogs, like rescue dogs or ones that travel and move with their owners. This is how Dog Flu has spread from state to state.
  • Many dogs are boarded, go to daycare, dog parks,  or visit grooming facilities where close contact to other dogs puts them at high risk.
  • Chicago is a dense and very dog friendly city.  Most dogs pass other dogs in the hallway of highrises, while out for walks and in elevators. 
  • It is easily spread between dogs:
    • Direct contact: when dogs kiss, lick or nuzzle each other
    • Through the air: from a cough or sneeze
    • Contaminated objects: doggie bowls, toys, doorknobs or clothing, walls, plants etc
    • Human touch

Signs Your Dog May Have the Flu

  • Lethargy (tiredness)
  • Decreased or Loss of appetite
  • Cough, which may be dry and honking or may bring up sputum. Clients often worry their pet is choking.  The cough is often, but not always, noticed at night. 
  • Runny nose with clear secretions, that may change to a thick and yellow and/or pink-tinged color
  • Increased breathing rate or effort
  • High fever(103°F)

Take this Quiz to Determine How at Risk Your Dog is of Catching Canine Influenza. 

Up-to-Date Outbreak Map

Links to Further Information:

Dog Flu History

How Can My Dog Catch the Dog Flu?

Symptoms of Dog Flu

How is Canine Influenza or Dog Flu Diagnosed?

Treatment of Canine Influenza or Dog Flu

How Can I Prevent My Dog from Catching the Flu?


Contact Us Today To Protect Your Dog From the Flu Or If You Are Concerned Your Dog Has the Flu!



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