In April and May 2017 there were outbreaks of canine influenza virus in Southern California, Florida, Georgia, Tennessee, North Carolina, Pennsylvania, and Texas. These cases have all been due to the canine influenza (CIV) strain H3N2. This is the same strain responsible for the severe outbreak of canine influenza in Chicago and Atlanta in 2015. In several of the states, H3N2 had not been identified previously. All prior cases of CIV were due to H3N8. CIV has continued to spread around the United States in recent years and this should be a concern to all dog owners.
It appears that many of the recent cases in the Southeast and Texas are related to dogs that were at one of two dog shows in Georgia and Florida, and it demonstrates how rapidly and easily CIV can be carried anywhere and subsequently infect a number of other unprotected local dogs. Currently, veterinarians in these states are treating many dogs that are suspected to have dog flu. Dog owners are advised to protect their dogs against this newer CIV strain through vaccination.
Symptoms of canine influenza often mimic other common upper respiratory infections. The most common symptom is a cough that persists for 10-21 days despite treatment. Dogs may have a soft, moist cough or a dry hacking cough similar to "kennel cough." Discharge from the eyes or nose, sneezing, lethargy, or decrease in appetite may also be seen. Many dogs develop a secondary bacterial infection causing high fever and nasal discharge, or even pneumonia.
We are now recommending that any dog that comes in contact with other dogs be vaccinated against the H3N2 virus. Dogs that go to boarding and day care facilities, groomers, dog parks, etc. should all be vaccinated. We have undertaken this program due to our experience with CIV outbreaks in other parts of the country and feel strongly the best policy is to always prevent diseases to the best of our ability.
In November 2016, the first vaccine that offers protection against both H3N2 and H3N8 became available. Initial vaccination involves a series of two vaccines given two to four weeks apart, and then annually thereafter. The vaccine provides protection against both strains of CIV currently recognized in the US (H3N8 and H3N2). Just as in human medicine, the vaccine may not completely prevent infection, but it will significantly decrease clinical signs, severity of disease, and spread of CIV infection.