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July Sneak Peek

Canine Influenza – Don’t Let the Hype Take Your Breath Away

By Dr. Luke Peterson, DVM

The media quickly locked onto the canine influenza outbreak that began in early April in the Chicago area and other nearby Midwestern states. The flu always seems to get their attention and for good reason. Historically, influenza viruses have been responsible for millions of deaths of humans, swine, poultry and other domestic animals. Luckily for us, this magnitude does not occur in dogs with influenza but that could change in the future if the virus mutates. There are always three important questions scientists seek to answer when dealing with influenza isolated from animals:

Is it zoonotic (can it infect people)?

Can it infect other species?

From where did it originate (both geographically and host species – for example, did it come from swine in Asia or poultry in California)?

Canine Influenza Background

Canine influenza in general has a relatively young existence in the United States. The most common strain H3N8 was first isolated in 2004 in racing Greyhounds. This flu strain originated in horses and has now adapted to dogs as a unique canine strain and has no evidence of being infectious to humans. The strain that has caused the most recent outbreak has been identified as H3N2 and has been reported in Alabama, California, Texas, Massachusetts, New York, Wisconsin, Michigan, New Jersey, Iowa, Indiana, and Georgia. This strain appears to be more contagious than the H3N8 strain. A recent genetic analysis shows this strain has very low potential for infecting humans. (As a side note, there is a human H3N2 influenza strain but it is not the same virus as the Canine influenza H3N2 strain.) A canine H3N2 strain was identified in Asia in 2007 originating from avian influenza and some have speculated the current US outbreak was introduced by infected dogs imported from Asia; however there is currently no evidence to support or deny this speculation.

Don’t miss the rest of this article. It’s on page 16 of our July issue!