Canine Influeza: Symptoms, Treatments and Prevention


Canine influenza is a contagious respiratory disease in dogs. Two canine influenza viruses have been identified worldwide: influenza A H3N8 virus and an influenza A H3N2 virus. Previously, canine influenza A H3N8 virus was identified in U.S. dog populations, although testing suggests the virus responsible for the recent Chicago outbreak is H3N2 similar to the Asian H3N2 virus detected in dogs in parts of Asia since 2007.

What are the Signs of Canine Influenza?

Signs of flu infection in dogs include cough, runny nose and fever, but not all dogs will show signs of illness. The severity of illness can range from no signs, to severe illness resulting in pneumonia and sometimes death.

Dogs with mild illness often have nasal discharge and a cough that is typically moist. In most cases, the symptoms last ten to 30 days and usually resolve over time.

Dogs with more severe illness may have a high fever (above 104 degrees Fahrenheit) and often develop signs quickly. Pneumonia, specifically hemorrhagic pneumonia, can develop. The influenza virus affects the lung capillaries, so the dog may cough up blood and have trouble breathing, if there is bleeding into the alveoli (air sacs). Patients may also have a secondary bacterial pneumonia, which can further complicate the situation.

Can I Catch Canine Influenza from My Dog?

No known human infections with either canine influenza virus have ever been reported. There have been some reports in Asia of the H3N2 virus affecting cats.

How Do I Know if My Dog Has Been Infected?

If canine influenza is suspected, your veterinarian will want to perform a physical examination and a complete blood count and clinical chemistry on your dog. Usually, increases are seen in the white blood cells, specifically the neutrophils that are destructive to microorganisms.  Radiographs of the dog’s lungs can characterize the type and severity of pneumonia.

A nasal swab and blood tests can support a canine influenza diagnosis, depending on the stage of disease. In most cases, a blood sample is taken after initial symptoms develop and then again two to three weeks later.

Is it Treatable?

The mild form is usually treated with antibiotics (to address any secondary pneumonia) and sometimes cough suppressants.  Rest and isolation from other dogs is also important.  The severe form needs to be treated aggressively with a broad spectrum of antibiotics, IV fluids, and hospitalization with general supportive care until the dog is stable.  The vast majority of dogs recover within two to three weeks.

How Can I Prevent My Dog from Catching Canine Influenza?

A vaccine for the H3N8canine flu is currently available, but it is not yet known whether it offers any protection against the H3N2 strain.  Whether to vaccinate your dog is a topic to explore with your veterinarian.

To date, the outbreak first seen in Chicago has been limited to mid-western states, so a high degree of worry in our region is probably not warranted.  That being said, the American Veterinary Medical Association provides general guidance:  Dog owners should be aware that any situation that brings dogs together (e.g., dog parks, shows and sporting events, and boarding) increases the risk of spread of communicable illnesses. When boarding, ask kennel managers whether respiratory disease has been a problem, and whether the facility has a plan for isolating dogs that develop respiratory disease and for notifying owners if their dogs are exposed.

Canine influenza virus can be spread via direct contact with respiratory secretions from infected dogs and by contact with contaminated inanimate objects. Therefore, dog exhibiting other symptoms should be isolated, and clothing, equipment, surfaces, and hands should be cleaned and disinfected after exposure to prevent transmission of infection. Clothing can be adequately cleaned by using a detergent at normal laundry temperatures.


Canine influenza is an illness that dog owners should be aware of and educated about, but not one that should cause excessive concern.  If you have additional questions about the illness or your pet, you should contact your veterinarian.

Dr. McCarron is the owner of University Veterinary Hospital & Diagnostic Center in Salt Lake City. She is board certified, specializing in canine and feline practice, and a member of the American Association of Feline Practitioners. Dr. McCarron has enjoyed serving Wasatch Front pets for more than twenty years.