Canine Influenza Virus 2015: the Midwest Outbreak

Wow, doesn’t that title sound dramatic?  I have a lot of media outlets to compete with!  Okay, seriously, though: the reason I started this page is to be able to inform concerned pet owners in an efficient manner when something comes up that people are worried about.  Right now I am fielding a TON of questions about the canine influenza virus (CIV) outbreak in Chicago.

First of all, for those who don’t know me, I’m from central Wisconsin, about four hours north of Chicago.  What I say and recommend is not coming from the front line, where the disease is active, and I have never seen a case of CIV that I know of.  Second, what I’m posting here is a copy of the handout I created to distribute to the pet owners who come to the veterinary clinic I work at.  That means my target audience is pretty limited, and may not pertain to every reader.

I will do my best to keep this information up-to-date, but with two jobs and two very busy sons, I often run out of time before I run out of errands.


There are currently two types of canine influenza virus known to infect dogs in the United States.  The first is H3N8, which made headlines about ten years ago when it caused illness and death in racing greyhounds, primarily in Florida.  I call it “the Florida strain”.  The second is H3N2, which was diagnosed in dogs in the Chicago area in March and April of 2015.  This is being referred to as “the Midwest strain”.

  • Both viruses are spread the same way, cause the same symptoms, and are treated the same way.
  • Neither one affects people, as far as we know, but the Midwest strain may cause symptoms in cats.
  • As of April 13, 2015, there is no vaccine available specifically for the Midwest strain.  However, the vaccine that has been used for the Florida strain is considered safe and may be effective in helping to control the Midwest strain.


Nearly 100% of dogs that are exposed to CIV will become infected.  Of those, roughly 20% will not show symptoms, even though they are still spreading the virus.  Eighty percent will become ill, but less than ten percent of those are expected to become so sick that they require hospitalization.

The virus destroys the lining of the airways, which allows other viruses and bacteria to cause secondary infections.  CIV itself only causes mild symptoms (cough, fever, maybe runny  nose) that last no more than three days.  However, the secondary infections cause more severe and longer-lasting symptoms, and can allow the CIV to hang around longer.  This is very similar to what we see with Kennel Cough, which is also a combination infection.  Just like Kennel Cough, we expect the symptoms of CIV to last up to a month.

Common symptoms include:

  • coughing
  • sneezing or runny nose
  • fever
  • decreased energy level and appetite
  • increased respiratory rate or panting
  • in severe cases, difficulty breathing, blue lips or tongue, and collapse


To me, testing is not really necessary from an individual pet’s standpoint, as it is not likely to change the course of treatment or the expected outcome.  However, from an epidemiological standpoint, testing is important because it allows us to track and better characterize viral outbreaks.  This allows the veterinary, medical, and research communities to know where to focus our efforts in regards to preventing and treating diseases.

Testing is a bit tricky, though:

  • For the Florida strain, something called a PCR test is the best, as it identifies actual genetic material from the virus.  False positives just don’t happen: if the test says the virus is there, then it’s there.  On the other hand, false negatives DO happen: if the pet has had symptoms for more than four days, the number of virus particles present may be too low to get a positive test result.  Also, if the pet  has the Midwest strain, the test for the Florida strain will be negative.  Apparently a test for Influenza A will detect the Midwest strain, but I’m not sure yet that such a test will be widely available to regular veterinarians.
  • There is another test called a serology test that is considered accurate, but does not do much to direct the therapy for an individual patient.  It is very helpful for communities, however, because it does help identify and track outbreaks.  Serology testing involves collecting a blood sample from a pet within the first week of it showing symptoms.  That sample is frozen and stored for two weeks, when a second sample is collected from the patient.  Both samples are sent to the same laboratory at the same time, and tested for the presence of antibodies against the virus.  The antibodies are produced by the pet as he or she is fighting off the virus.  If the second sample has higher levels than the first, it means the pet did have an active CIV infection.  However, since you don’t know this until about three weeks after the pet has become ill, you have to treat and quarantine while you wait for the results.  That means that a positive result helps the community to know that the virus is active in the area, but it doesn’t help that individual pet.


Treatment is aimed at supporting the immune system, managing symptoms, and treating secondary bacterial infections.

Supporting the immune system can include:

  • providing good quality food and clean water in a stress-free living environment
  • giving antioxidants, omega fatty acids, and probiotics
  • alternative therapies such as acupuncture, chiropractic care, herbal remedies, or homeopathic treatments.  Make sure you find a certified specialist in each of these areas!  Although these modalities are considered “alternative”, that doesn’t mean that just anyone can practice them SAFELY.  Keep your pet’s safety in mind and choose ALL health care providers wisely.

Managing symptoms may include:

  • cough suppressants
  • appetite stimulants and/or anti-nausea medications
  • fever reducers (remember that fevers are part of the healing process, though, so don’t be surprised if your veterinarian doesn’t want to treat them!)
  • medications to decrease nasal discharge or open up the airways

Treating secondary bacterial infections requires antibiotics.  In some cases a culture and sensitivity test will be run to help choose the correct antibiotic.


The virus is spread the same way that the human cold virus is: through aerosolized secretions that contain viral particles.  In English, that means that the snot and spit that an infected pet coughs and sneezes into the world sends little drops of fluid flying around.  Those drops have living virus in them.

I know: GROSS.

Anywhere those droplets land, there will be virus that could cause an infection.  That means the viral particles can be breathed in, land on flat surfaces, clothing, people, other animals….You get the idea.  The virus can survive for up to 24 hours on clothing/skin/fur, and up to two days in the environment (building, inside of a vehicle, on a fire hydrant, whatever).

Pets have the largest number of virus particles in their snot/spit within the first seven days of becoming infected.  For the first three days, they probably aren’t showing symptoms.  That means that by the time your dog’s best friend starts coughing, your dog has already been exposed.  Viral shedding drops off four days after the symptoms began, but pets are considered contagious until all of their symptoms are gone, partly because we don’t know what secondary infections they have and how long THOSE organisms are shed.


The vaccine that is currently on the market does not prevent infection.  It decreases the severity of symptoms, may decrease the length of time that a pet has symptoms, and can decrease the amount of virus that an infected pet sheds.

In order to be effective, two vaccinations must be given two or three weeks apart.  The pet is not considered immunized (meaning it doesn’t have a high level of antibodies to fight off the virus) until at least two weeks after the second vaccination was administered.  That means that from start to finish it takes a minimum of four weeks for a pet to be immunized against CIV.

Other things to keep in mind when considering whether or not to get your pet vaccinated against CIV:

  • the vaccine that is being marketed right now is for the Florida strain. It may or may not help with the Midwest strain.
  • vaccination is recommend for AT RISK dogs, not EVERY dog.

Which dogs should be vaccinated?  Basically, if you live in or are travelling to an area where there is a CIV outbreak, you have at least a month to get the vaccines working before your pet’s potential exposure, AND your pet will be mingling with other dogs (i.e. is in a situation where your vet would recommend the Kennel Cough vaccine), your pet falls into the “at risk for exposure” group and vaccination may be beneficial.  If you live far from a big city or anywhere that an outbreak is occurring and your pet is a homebody, the risk of exposure is low, and the vaccination is considered unnecessary.

So how do I protect my dog?  The best way to prevent infection is to prevent exposure.  That means that WHEN THERE IS AN OUTBREAK IN YOUR AREA, you should keep your pet away from other animals: no boarding, grooming, showing/competitions, training, or trips to the dog park.  Minimize trips to the veterinary office, too!  Ask your veterinarian if things like nail trims, anal gland expression, or even some vaccinations can be delayed until the outbreak ends.  If there is an outbreak in another area of the country, avoid travelling there with your pet or allowing your pet to come into contact with animals that have been in that area around the time of the outbreak.

What should I do if my dog is coughing or has a runny nose?

  • First, quarantine it and any other pets that live in your household.  They can go outside on a leash to go to the bathroom, then come right back inside.  If you REALLY want to be careful, you’ll wash your hands and change your clothes before you leave the house, and keep your shoes in the garage or car so they don’t pick up virus particles.
  • Second, call your veterinarian as soon as possible.  Pets that are started on antibiotics early stand a better chance of avoiding a hospital stay later.
  • Third, be sure to follow your isolation protocol until your pet is symptom-free, and has been for at least three days.

The Midwest strain of CIV is what the experts like to call an “emerging disease”, meaning one that is fairly new to the disease-causing scene but is making itself famous quickly.  We expect to learn a lot about this virus in the coming weeks, so keep your eyes peeled for updates.

Remember, as always, that your own veterinarian is the best source of information about your pet, because medicine isn’t just science, and all patients don’t respond the same way to things!