Canine Influenza Outbreak in the Midwest

As you have likely heard there has been an outbreak of the canine influenza which started in Chicago a few weeks ago.  Throughout the Midwest more than 1,000 dogs have been infected with the virus and there have been 6 documented deaths secondary to the disease.  As with the seasonal flu that afflicts humans – it is now known that there are more than one strain of the canine flu.

The initial strain of the canine flu that was seen in the US back in 2004 was from the H3N8 strain and actually jumped directly from horses to dogs.  The outbreak in 2004 was first seen in racing tracks in Florida (then unfortunately travelled to surrounding tracts with the dogs).  The same strain later caused an outbreak in shelters in and around NYC.  Since this time it has become endemic in Colorado, Florida, New York and Pennsylvania.  A few cases have been reported in Massachusetts in the past few years including a cluster of dogs in Essex County in 2014.

The outbreak in Chicago was initially presumed to be caused by the H3N8 strain, but recent testing has concluded that it is actually the H3N2 strain.  The H3N2 strain has not previously been documented in dogs in the United States but rather had been confirmed in dogs in Asia (including Southern China and South Korea).

Unfortunately the current Canine Influenza vaccine that is commercially available is for the H3N8 strain and it is unknown if it provides cross protection for the H3N2.  This begs the question – should my dog be vaccinated for the Influenza virus?  Although this discussion is best had with your veterinarian – if your dog frequents areas of high dog traffic such as doggie day car, grooming, boarding and dog parks they may benefit from the vaccine.

Luckily similar to other upper respiratory infections seen in dogs (such as Bordetella/Kennel Cough and Parainfluenza) clinical signs if exhibited are often self-limiting and treated with medications.  Common clinical signs include persistent cough of 1-3 week duration, ocular or nasal discharge, fever, lethargy, anorexia and general malaise.  In a small percentage of dogs a more serious form of the disease has been seen which includes pneumonia, high grade fever or other respiratory issues.  In the initial outbreak among the racing greyhound population sudden death was seen – but this has not been documented in outbreaks among pet dogs.

Please feel free to stop by or make an appointment for your dog at Medfield Veterinary Clinic or Westwood Veterinary Care to discuss the risk of Canine Influenza for your dog.  If your pet has not previously been vaccinated and does spend time in high dog traffic areas starting the vaccine series might be indicated.

-Dr. Sara Buckley

Medfield Veterinary Clinic and Westwood Veterinary Care are proudly serving the communities of Westwood, Norwood, Walpole, Dover, Dedham, Canton, Sherborn, Millis and Medfield.


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