Canine influenza has only been present in the United States since 2003, meaning many pet owners are unaware that dogs can get the dog flu—the spread of which is exacerbated through social activity among dogs. In 2015, a new strain of canine influenza emerged in the United States—H3N2—which is estimated to produce ten times more virus than previous strains and has already caused outbreaks in half of all U.S. states. According to clinical studies by researchers at the University of Wisconsin, H3N2 may be shed for an extended period of time—up to 24 days, which is far longer than what is seen with H3N8.1 Because the H3N2 strain is relatively new, close to 100 percent of dogs are naïve to the new virus and have no natural immunity to it, meaning virtually all exposed dogs become infected. Prevention is the best approach, and Merck Animal Health offers vaccines to protect against both CIV H3N2 and H3N8.
Common clinical signs of canine influenza include coughing, fever, sneezing, ocular discharge and lethargy. In severe cases, pneumonia can develop, and up to eight percent of critically ill dogs may die from complications.
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