What It Is


What is Safe for your pet continues with Canine influenza, or dog flu,  which is extremely contagious and is caused by the influenza A virus. There have been identified 2 different strains of influenza, H3N8 and H3N2. Until March of 2015, H3N2 appeared to be limited to China, Korea and Thailand when an outbreak was identified in the Chicago area. Originally emerging in 2006-2007 in Asia, dogs were suffering from respiratory disease. It is believed that this strain evolved from direct transfer of the avian influenza virus circulating in live bird markets to dogs. This new virus was responsible for a large outbreak in South Korea and China and in 2012 in Thailand. H3N8 was first noted in January of 2004 in racing Greyhounds in Florida. Six Max2states reported outbreaks affecting 14 racing tracks between June and August of that year. Outbreaks continued in 2005 with reports of outbreaks at 20 racing tracks in 11 states between January and May. The H3N8 strain went on to be documented in 41 states. When the H3N2 stain first occured in Chicago, outbreaks have been seen throughout the United States and more than 2,000 dogs have tested positive.

What It Does

Outbreaks are seen in situations where susceptible dogs are in close contact with each other. This would include dog day care facilities, boarding facilities, kennels and shelters. The virus is transmitted through:

  • Respiratory secretions from coughing, barking and sneezing
  • Objects that have been contaminated such as food and water bowls, collars and leashes
  • People that have moved between infected and uninfected dogs


The virus is able to infect for up to 48 hours on surfaces, on clothing for 24 hours and on hands for 12 hours. Generally the incubation period is 2 to 4 days from the time of exposure to the appearance of symptoms. Dogs are most contagious during the incubation period, and the chance of spreading the virus  greatly decreases during the first 4 days of illness, but may continue up to 10 in some dogs. It does not depend on age or breed, all dogs are able to become infected since there is no known immunity. While most dogs that become infected will have a mild form of canine influenza, some dogs will develop severe pneumonia. It is estimated that approximately 20-25% of dogs that become infected will show no symptoms but can still spread the virus. Infections are not seasonal and can occur year-round.

The most common symptom is a cough that can last for up to 21 days even if treatment includes antibiotics. Nasal and eye discharge, sneezing, lethargy, fever and decreased appetite can also be noted.  Your veterinarian can diagnose canine influenza a thorough physical examination and by running a series of tests.  The virus cannot be passed from dogs to humans.  As with any virus, the best course of action includes supportive measures and good nutrition to support your dog’s immune system. If a secondary bacterial infection would occur, it would require specific medications.

Preventative Measures

Common disinfectants go a long way to kill the influenza virus in boarding and shelter facilities and veterinary offices. Each facility should have a standard in place to ensure that surfaces are thoroughly cleaned and that all employees are washing their hands frequently. Isolation protocols must be established and strictly followed to prevent further spread of the virus.


A vaccine for the H3N8 virus has been available since May 2009 and acts to control the disease by limiting the severity and duration of illness. As of November 23, 2015 a vaccine is available for the H3N2 virus. The manufacture of the virus advises that researchers have determined that this strain is contagious for a far longer period of time, up to 24 days and it has been estimated that this strain produces up to 10 times needle-syringe-1198924more virus than the H3N8 strain. Due to this, it is highly recommended that dogs be vaccinated that are at greatest risk for exposure to the virus. Healthy dogs as young as 6 weeks can receive the vaccine. Merck Animal Health offers more information regarding Canine Influenza at doginfluenza.com.

4 comments on “Canine Influenza – What You Need To Know To Protect Your Dog

  • Loved the post, thank you for the great insight. A lot of information that I didn’t even know about pet safety. Definitely going to come back to this post when my dog start acting up. Loved how the post is laid out, it really helps me follow your points and get the information easy. Thanks for the informing post!

  • This was pretty scary to me when I first heard about it. We had gotten a notice from our dog walking group that they were temporarily discontinuing our walks at the dog park, so for awhile we stopped bringing our dog there. Better safe than sorry! From reading this article it sounds pretty contagious, and with the way dogs are all over each other during play I suppose it’s a good thing we held off. I’m happy to hear that a vaccine is available as I really haven’t checked into all this. Thanks for the info!

    • Hi Carol,

      That would be scary to know that your dog is at risk by hanging out with other dogs. I’m glad you got the notice so you were able to take action to protect your dog.

      Take Care,


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