Midwest Canine Influenza Outbreak: A New Virus Within the United States

Photo Credit: Steven Turville

If you keep tabs on dog-related news, you’re probably already aware of the recent outbreak of canine influenza in the Midwest. Chicago appears to be at the epicenter of the epidemic.

The first dogs affected by this virus were observed in mid-March of this year. Since then, more than 1,000 known cases have been reported in and around Chicago, and there have even been a few deaths.

New virus within the United States

Until a week ago, the virus responsible for this canine influenza outbreak was thought to be H398, a strain of Influenza A that has been present in the United States for some time. Cornell University (thumbs up to my alma mater) recently reported that scientists there have isolated a brand new influenza virus from affected dogs in the Midwest. This virus, referred to as H3N2, is closely related to strains of influenza affecting dog populations in South Korea and China. H3N2 is now making its debut appearance within the United States. How the virus was introduced here is anyone’s guess.

Dogs living within the United States have no natural protection against H3N2 because their immune systems have never been exposed to it before. For this reason, it will remain highly contagious until canine populations develop immunity, either through natural infection or vaccination.

The contagious stage of canine influenza begins a few days before symptoms arise. In other words, the healthy-appearing pup at the dog park or doggie daycare center may be on the verge of developing viral symptoms. Spread of the disease occurs via respiratory secretions (discharge from nose, mouth, and eyes). Both dogs and cats are susceptible to the H3N2 virus. It is not transmissible to humans.


The symptoms most commonly associated with influenza virus include: high fever, loss of appetite, coughing, nasal discharge, and lethargy. In the best-case scenario, an infected dog may show only mild symptoms or none at all. Worst-case scenario, pneumonia may develop. Pneumonia was the likely cause of death in five dogs who have reportedly succumbed to this disease.


Many infectious bacterial and viral diseases are capable of producing the symptoms described above. Knowing that H3N2 is the culprit requires specialized testing performed on a mouth or nose swab. Cornell reports that the development of a blood test capable of diagnosing this disease is in the works.


Treatment of influenza ideally involves supportive and symptomatic care until the dog’s immune system wins the battle against the virus (requires approximately two weeks for most dogs). Therapy may include supplemental fluids, special diets to entice appetite, anti-inflammatory medications, and cough suppressants. Antibiotics may be prescribed to prevent secondary bacterial infection.

If evidence of pneumonia is present, much more intensive therapy is indicated and may include hospitalization for intravenous fluids and antibiotics, supplemental oxygen, and 24-hour monitoring by a veterinarian.


At this time, it is not known if the vaccine currently available to prevent H3N8 is also protective against the newer H3N2 strain. There may be some cross over protection, but just how much is uncertain. I suspect that updated information about the effectiveness of the current vaccine and/or development of a new vaccine will be forthcoming in the near future. For now, I recommend discussing use of the current influenza vaccine with your veterinarian.

If you live in or around Chicago, or if you learn that influenza cases are beginning to pop up in your neck of the woods, know that the very best protection involves keeping your dog away from popular, public, canine venues such as dog parks, boarding kennels, grooming parlors, pet stores, and doggie daycare facilities.

Please know that there is no cause for panic. The vast majority of dogs affected by this new strain of influenza fully recover. Talk with your veterinarian about the incidence of canine influenza in your locale to help determine the level of concern for your dogs.

Have you had any experience with canine influenza? If you live in the Midwest, are you taking specific measures to protect your dog?

Best wishes,

Nancy Kay, DVM

Diplomate, American College of Veterinary Internal Medicine
Author of Speaking for Spot: Be the Advocate Your Dog Needs to Live a Happy, Healthy, Longer Life
Author of Your Dog’s Best Health: A Dozen Reasonable Things to Expect From Your Vet
Recipient, Leo K. Bustad Companion Animal Veterinarian of the Year Award
Recipient, American Animal Hospital Association Animal Welfare and Humane Ethics Award
Recipient, Dog Writers Association of America Award for Best Blog
Recipient, Eukanuba Canine Health Award
Recipient, AKC Club Publication Excellence Award
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Please visit http://www.speakingforspot.com to read excerpts from Speaking for Spot and Your Dog’s Best Health.   There you will also find “Advocacy Aids”- helpful health forms you can download and use for your own dog, and a collection of published articles on advocating for your pet’s health. Speaking for Spot and Your Dog’s Best Health are available at www.speakingforspot.com, Amazon.com, local bookstores, and your favorite online book seller.


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14 Comments on “Midwest Canine Influenza Outbreak: A New Virus Within the United States

  1. Hi Lisa and Adam. I think that some veterinarians have been recommending the vaccine that has been protective against the H398 version of influenza for one of two reasons. They may not yet be aware that the current influenza outbreak is being caused by a virus that is new to this country. Or, if they do know this, they may be hoping that there is some cross protective immunity (to date, this has not been proven or disproven). I agree that use of the current vaccine may, in part, be fear based. What they may not realize is that the vast majority of dogs who contract influenza make a complete recovery. I would have a hard time recommending the H398 vaccination based on our current knowledge.

  2. Dr Kay,
    We’d love to hear your thoughts on why the current H398 vaccine protocol is being recommended at all in this instance where the H3N2 is a completely different strain of the virus? It seems counterintuitive to engage our dogs’ bodies in dealing with a vaccine at a time when strengthening their immune systems (rather than taxing it) is paramount to handling this new strain if they were to be infected. Concerned the recommendation of a vaccine may be a more fear-based (and possibly revenue-based) than an advisable measure of protection.
    Thank you very much for your article.
    Kindest regard, Lisa and Adam

  3. In defense of HSUS for saving Korean dogs from the meat trade, I’m so thankful these dogs are today playing and not in someone’s toilet. Please note that there are people purchasing from S. Korea. Today, Paris Hilton is on the MSN Celebrity News, which states:
    “She ordered the dog from a Canada-based business that arranges for puppies in South Korea to be shipped to buyers overseas, according to the newspaper The Calgary Sun. The outlet reported on Friday that the seller, Joanne Pauze, did not reveal how much Hilton paid for the dog and added that it was worth $13,000.”

  4. I first heard of this flu outbreak in NYC, a week or 2 before it hit Chicago. As soon as I heard of mortalities we stopped going to the dog park. I have 5 huskies, and couldn’t afford the hospital care without going deeply into debt. So on many levels, I cannot “afford” to take chances with my dogs. We avoid all dog venues, even though as far as I know, it hasn’t hit the West Coast yet.
    “The University of Wisconsin-Madison’s School of Veterinary Medicine says the virus has sickened at least 1,000 dogs in Illinois, Wisconsin, Ohio and Indiana. ”

    This is frightening; I recently signed up to foster dogs rescued from the asian meat trade, through a local rescue group. I assumed they would go through some sort of quarantine?

  5. We’re getting our dogs vaccinated on the advice of our vet. The Goldendoodle goes to the groomer every few weeks, and they’re both going to “camp” at our sitter’s home during an upcoming trip. I used to let them socialize (on leash) at the vet’s office, but not on this trip.
    We’re in St. Louis-only a 5-hour drive from Chicago-so anything that starts there eventually shows up here.

  6. I compete quite regularly at agility trials in Northern Virginia. I called my vet’s office this week and asked if I should stay home. They didn’t consider it to be high risk as the MD/DC/VA area hasn’t been hit yet. I did crate from my car instead of inside the sportsplex, and I never let my dog socialize at a trial anyway.(he’s not always polite!) I have healthy, vigorous dogs so I am not too worried. I will not vaccinate unless the situation get much more grave. (I don’t get the flu vac for myself either.) I do wonder whether the dogs who went on to develop pneumonia/died were compromised by other health issues or were maybe young puppies. The news media cares only about stirring panic and doesn’t report on those kinds of details.

  7. Hi there. Hopefully, by late May, the influenza virus will not have spread significantly from the Midwest. You might want to play it by ear based on reports you are hearing.

  8. Never dealt with flu in my guys, hopefully will not in the future. The upside we live in rural area on Northern Ontario now, so perhaps it doesn’t make its way here at all.

  9. it is likely that this flu strain was brought to America by the international branch of HSUS by importing Korean dogs from the meat trade for resale. Unlike private breeders, these rescue organizations operate without regulation or quarantine.

  10. Dr. Kay, in late May we are supposed to attend a pet blogger conference in Nashville, where many dogs, cats and other animals will be present. Do you feel it’s safe to take our GSD Wyatt to the event? Would it be just as risky to board him? Any thoughts greatly appreciated.

  11. I live a couple hours away from Chicago and we now have had several dogs diagnosed with flu. At this time, they still have not determined which flu virus strain it is, but events at the university veterinary hospital that involved dogs were cancelled for the big spring weekend event in light of the Chicago epidemic. I’m not terribly worried since my dogs don’t like being social and are not exposed to other dogs generally. However, I do have a compromised Cocker Spaniel who will have to go for a pancreatic and kidney recheck in a week and I admit taking her to a vet clinic scares me a little.

  12. My 3 Bernese Mountain Dogs will begin their vac series tomorrow.
    We are in northern lower Michigan, have MANY tourists enjoying our precious picture postcard world here. A boarding facility nearby closed and is awaiting results from blood testing on dogs who became ill while there. I am concerned for my Berners so want to be proactive as possible. Hopefully The vac will give them some immunity. We are NOT going to any Dog Parks or places where dogs frequent. Not even having playtime with dog friends who have traveled or been recently boarded.
    This IS frightening to me!

  13. There have been numerous cases of canine influenza at a shelter (Gwinnett County) in Georgia, with three dying. I do not know which strain was involved.

  14. I’m in central Indiana. I have stopped taking my dogs to the pet store with me unless they need grooming or nails done. Even that worries me. If a vaccine becomes available I’ll be first in line.