TRUE OR FALSE? 10 Common Canine Influenza Beliefs Explained


By Sue M. Copeland with Jason Stull, VMD, MPVM, PhD, DACVPM

You’ve heard of the outbreaks: Canine influenza virus (CIV) hits a region or regions; thousands of dogs are infected. Most survive, but there are fatalities.

Misinformation abounds. How do you make the right choices to protect your dog?

To help, we consulted canine infectious disease expert Dr. Jason Stull, Assistant Professor, Department of Veterinary Preventive Medicine at Ohio State University. He recently led a study team to develop recommendations to prevent canine infections, including CIV, in places where dogs gather, such as shows, events, and kennels.

We gave Dr. Stull 10 common CIV beliefs, and asked him to rate them “True” or “False.” Here’s what he had to say.

  1. True or False: As with human influenza, there are multiple strains of CIV.

    TRUE. There are currently two known CIV strains in the United States. The first one is H3N8, which is equine in origin.

    That’s right: The virus morphed, via adaptive evolution, from being an equine influenza virus to a canine-specific one. It originally spread from racehorses to greyhounds at the same Florida racetrack in January 2004. Since then, the strain has been documented in 40 states and Washington, D.C. It appears to be most common in areas of Colorado, Florida, New York, and Pennsylvania.

    The second, more recent strain is H3N2. It originally seemed limited to Korea, China, and Thailand. Then in March 2015, an outbreak occurred in the Chicago area (spreading to other Midwestern states) that was determined to be due to an H3N2 strain. From there, it acted like a typical flu virus: It moved quickly in a short amount of time, and caused a lot of disease in dogs. Since March 2015, outbreaks have occurred in a number of U.S. areas; thousands of dogs have been confirmed positive for the H3N2 virus.

    (Flu trivia: H3N2 is likely avian, meaning bird, in origin. All flu viruses are believed to start in birds.)

  2. True or False: The current vaccines for H3N8 and H3N2 are highly effective.

    TRUE AND FALSE. Unlike some canine vaccines that are highly effective at completely preventing infection and illness (such as for Rabies and Parvovirus), H3N8 and H3N2 vaccines don’t generally completely prevent the disease. Instead, they’re considered tools in a multi-faceted approach to help control CIV’s spread. (See “Flu-Fighting Tips," below.)

    However, they can help reduce CIV’s severity and duration in your dog, which also helps limit its ability to spread.

    My study team recommends that you consider vaccinating your dog for CIV if you live in an area that has flu outbreaks, or are taking your dogs into high-risk settings, such as shows, kennels, or dog parks. Both vaccines consist of an initial dose, followed by annual boosters.

    So far, there doesn’t appear to be cross-protection between the H3N2 and H3N8 vaccines. To find out which one would be appropriate for your dog, consult your local veterinarian. He or she will be able to tell you what strain is occurring in your area, and guide you in choosing the best CIV vaccine(s) for your dog.

    Note: Just recently, it was announced that there is a new vaccine that covers both strains. For more information, go to Dog Influenza.   

  3. True or False: The U.S. has a strong program in place for tracking canine flu outbreaks.

    FALSE. There is no national (nor state) CIV tracking. There is, however, good information available from Cornell University College of Veterinary Medicine, via their Canine Influenza Virus Surveillance Network, which includes outbreak updates and maps, but it is in no way fully comprehensive. 
    As a result, we don’t have complete information about total numbers of dogs affected by CIV, or by which strain.

    Without data to track, it is difficult to quantify a flu outbreak’s breadth and impact. With human flu outbreaks, the Centers for Disease Control and Prevention (CDC) does the tracking. For that to happen in dogs would require state and national action. (Currently, Rabies is the only canine disease that is tracked nationally.)

  1. True or False: All infected dogs show signs of infection (typically coughing, sneezing, fever, lethargy, and nasal discharge).

    FALSE. About 80 percent of infected dogs will show signs of illness. The other 20 percent will carry the virus but show no signs. That doesn’t mean they aren’t contagious!

    If your dog is infected, he will typically shed the most virus (meaning he’s at his most contagious) in the first few days after being exposed to the virus, whether or not he is showing signs.

    However, if your dog has been vaccinated against CIV, regardless of whether he shows any signs of the disease, he may be less infectious, and infectious for a shorter time, than will an unvaccinated dog.

  2. True or False: The flu virus is relatively easy to contain, and to kill with common disinfectants.

    TRUE. CIV is transmitted through respiratory droplets when an infected dog coughs, sneezes, or simply breathes. The droplets typically travel only a few feet, and can live on a surface for about 48 hours.

    That leaves plenty of time and opportunity for CIV to be picked up by your dog and other dogs, either through nose-to-nose contact, or by sniffing or licking an area on which the virus has landed. (That could be shared bowls, crates, beds, grooming tables and equipment, leashes, and toys. Or, your dog could pick up the virus simply by sniffing a spot on the floor on which an infected dog has shed it.)

    We humans can act as conduits for the virus as well. If you touch an infected dog’s nose or mouth, then touch another dog (or toy, or brush, or leash), you can inadvertently spread the virus. That’s why proactive preventive measures are important to help stop the spread of CIV (and other infectious diseases).

    So, wash your hands with soap and water--or use a hand sanitizer--frequently. This is especially important between contact with each of your dogs (or any dog) during an outbreak. Avoid sharing bowls, toys, crates, beds, and grooming equipment. And disinfect shared areas with a product shown to kill CIV, such as a solution of 1-part household bleach to 30-parts water.
  1. True or False: The CIV vaccine can give your dog the flu.

    FALSE. The virus in canine flu vaccines is “killed,” meaning it has been inactivated, so it can’t infect your dog.

    It will, however, fire up his immune system, which is how it serves to protect him. That means he may feel a bit puny for a few days, but he will NOT be shedding the virus. He WILL be developing a level of immunity against it.

  2. True or False: You can’t catch the flu from your dog.

    TRUE. H3N8 does not infect other species (including humans) at this point. However, in March 2016, it was reported that cats in an Indiana animal shelter had been infected with the H3N2 virus, which had spread to them from dogs. Cat-to-cat transmission can then occur. There currently is no flu vaccine for cats.

  3. True or False: CIV can affect dogs of any age or breed.

    TRUE. However, as with any infectious disease, puppies (especially those under 6 months of age), have immature, evolving immune systems, so are more susceptible to CIV. They are also more likely to suffer a severe bout of the disease than are dogs with mature immune systems.

    Conversely, senior dogs, which have waning immune systems, also are more susceptible to CIV and its severe forms than healthy, younger dogs.

    Brachycephalic breeds (those with short, flat faces), such as Boston Terriers, Boxers, Pekingese, Pugs, and Shih Tzus are perhaps more likely to have respiratory complications from CIV and other respiratory diseases, and their recovery may be slower, than other breeds.

    If you are planning to take your puppy or senior dog to a show, kennel, or any event or location in which there will be a large number of dogs, be sure to consult with your veterinarian. It is important to remember that all infectious disease risks (not only CIV) are generally greatest for young and senior dogs.

  4. True or False: CIV is highly fatal.

    FALSE. Generally, fewer than 10 percent of infected dogs will die from CIV or result in complications. (The exact number is hard to quantify because there is no national tracking system.)

    The vast majority of infected dogs, like people with the flu, will have a limited course of the disease. In other words, it may be unpleasant but not fatal. And, as with humans, many dogs recover without a visit to their “doctor.”

    Typically, dogs infected with H3N8 will recover around two weeks after first showing signs, so likely will no longer be shedding virus at that time. Dogs vaccinated against CIV that have been infected generally are sick (and are shedding the virus) for less than two weeks.

    H3N2-infected dogs can shed virus for about 21 days. Therefore, the American Veterinary Medical Association suggests that you isolate an H3N2-infected dog for three weeks. (If you suspect CIV in your dog, but do not know the strain, it would be best to use the three-week-isolation recommendation.)

    A caveat: As with each flu season in humans, there is always a chance that CIV will mutate and change, resulting in a higher mortality rate. That’s why we need more and better data, to help track the disease. (For more information on how you can help track and monitor canine infectious disease, see the “Containing Canine Disease," below.)

  5. True or False: Treating your dog with antibiotics will kill the virus.

    FALSE. CIV is a viral infection. Antibiotics are only effective against bacterial infections. Plus, when you randomly treat a sick dog with antibiotics, without knowing if the illness is viral or bacterial in nature, you risk creating resistance to antibiotics, which can make future infections harder to treat.

    That said, your veterinarian will prescribe antibiotics, if necessary, if your dog develops a secondary bacterial infection due to CIV, such as bacterial pneumonia.



Use these tips to help limit the spread of CIV.

  • Leave any dogs with signs of infection at home. These can include lethargy, coughing, and sneezing.
  • Isolate CIV-infected dogs for 3 weeks. This means keeping these dogs away from all other dogs, and being careful about accidentally moving the virus to other dogs on objects, such as bowls—or your hands or clothing.
  • If you touch dogs in group settings (such as in your kennel, or at shows or other events), frequently wash your hands with soap and water, or use a hand sanitizer.
  • Avoid sharing items such as leashes, bowls, and toys.
  • Minimize unnecessary dog-to-dog contact.
  • Regularly disinfect community surfaces (such as floors, crates, bedding, grooming tables and grooming equipment) with a product effective at killing CIV, such as a solution of 1-part household bleach to 30-parts water.
  • Keep your dog’s vaccines up to date; talk to your veterinarian about the best CIV vaccination program for him, based on his lifestyle.
  • Take care when bringing puppies and seniors to shows, events, dog parks, or any place where lots of dogs congregate. Talk to your veterinarian about the risk of illness (and whether it should outweigh any benefit, such as socialization).



In research supported by the AKC Canine Health Foundation (CHF) and the Orthopedic Foundation For Animals (OFA), Dr. Stull and a team of collaborators reviewed more than 400 academic papers related to halting the spread of canine disease, including CIV.

As a result, the team produced new guidelines intended as tools for those of you in charge of canine group settings, such as dog shows/events, and kennels, as well as for dog owners.

“When you have many dogs in a fairly confined space, the opportunities for disease transmission are everywhere,” says Dr. Stull.

“In veterinary medicine, we’re probably 30 years behind in our infection control and tracking efforts, compared to those in human medicine. But a lot of the risks can be managed with some simple steps,” he continues.

Dr. Stull and his team recommend that kennel staff, and show and event coordinators develop a surveillance program to monitor for infectious diseases, focusing on dogs that develop clinical signs at their particular setting. Doing so allows for early recognition of disease transmission and outbreaks.

The full report, including the study team’s recommendations for disease recognition and response by staff and organizers, as well as a “risk calculator” for infectious disease, plus fact sheets addressing particular canine diseases, is available through the Ohio State University College of Veterinary Medicine.

This article originally appeared in DN Magazine and is reprinted here with permission.

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