Canine Flu

An acknowledgement up front–I am a compensated speaker for Intervet Schering Plough Animal Health, makers of the canine influenza vaccine currently on the market (there may be others on the way).  But my interest in canine flu preceded Intervet having a product on the market.  My interest began in the intake facility in Philadelphia’s animal control facility, where part of my world of shelter medicine took place for several years.  Canine infectious respiratory disease complex, overly-reduced to “kennel cough”, troubles every shelter from time to time.  In very high volume shelters, it is more or less persistent.  There isn’t much control over the intake numbers of dogs, and given the strain on the facilities, upper respiratory disease (sneezing, nasal discharge, spontaneous cough) is pretty common, and the risk increases with each successive day in the shelter.  Such was the environment in 2007.  And then, the number of dogs increased dramatically, and the persistence and severity of the cough changed, too.

Flashback to Florida, 2004.  An outbreak of severe Canine Infectious Respiratory Disease Complex was under investigation in a Greyhound kennel in Florida.  An influenza virus was isolated, related to equine influenza, but now established infectious agent of dogs, complete with dog-to-dog transmission.  This was the first description of influenza jumping from horses to dogs and staying to dogs.  The lead investigator,

Cynda Crawford, is in the Maddies’ Shelter Medicine program at the University of Florida.  What she found was that influenza of horses somehow got transmitted to these Greyhounds and then changed-mutated, and became a stable infectious influenza of dogs.  Since that initial description in a Florida Greyhound kennel, the virus has been confirmed in 30 states, and is considered endemic (common) in Pennsylvania, New Jersey, New York, Colorado, and Florida.

With consultative assistance from the ASPCA, canine influenza was confirmed in Philadelphia.  At the Vet School at Penn, we also saw cases coming in from the shelter, and did develop some experience in treating these patients as part of our student surgery program and from cases seen through the Ryan Hospital.

Canine Influenza Virus is highly contagious from dog to dog, and since most dogs are not vaccinated and are considered immunologically naive (no prior “street” virus exposure), most dogs are susceptible.  There is no breed, age, or sex predeliction

Michael Moyer and Cynda Crawford

, and vaccination statue (apart from influenza vaccination status) is not important.  Dogs vaccinated for Bordetella and parainfluenza are still highly susceptible to canine influenza virus.

In my mind, I always thought of respiratory flu as primarily an upper respiratory (cough, sneezing) problem, until I saw the pathology wrought by canine influenza in the lungs of affected dogs.  This is a profound lower respiratory disease, and can easily result in pneumonia. When I saw the lung pathology images, it was no surprise that these dogs cough and will not typically respond to cough suppression–huge amounts of goo and damage lung bits means lots of coughing for a long time.  With luck and support, most dogs will survive, but a very small unlucky few will decline in their breathing to a point where ventilatory support is needed.

So, is Dr. Moyer recommending vaccination across the board for all dogs?  No, but if you think that your dog’s risk for plain old Bordetella was worth the vaccination, you should probably add Canine Influenza Virus vaccination to your “To Do” list for Fido.  Dogs that kennel, go to doggie day care, high traffic dog parks in at risk communities (it isn’t in every community, but it is certainly in and around Philadelphia).  I pose some mild risk to my own dog, because I see the students’ pets at the Vet School, many of which are rescued from very high risk environments.  Please note–it is not a disease of shelters, but one that is more likely diagnosed and detected in shelters, owing to their constant intake and turnover.  But it is a disease of the community of dogs in an area, and other dogs are also at risk.

For my clients’ dogs, I recommend consideration if the dog kennels or is going to doggie day care facilities.  Some grooming facilities are requiring it, as are many boarding kennels. Oh, and I’d make sure the Bordetella and parainfluenza was updated by the intranasal spray vaccine, too.  Canine flu is new;  not every vet has experience with it yet, and the jury is still out on how widely this thing will spread.  Virologists familiar with influenza are watching this one carefully;  it isn’t behaving quite as aggressively as other flu viruses–if it changes, it may become more “successful” at infecting dogs.  Until then, though, it looks as though it has restricted itself to a handful of states, with Pennsylvania being one of those lucky few.

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