In March 2017, H3N2 canine influenza was identified in dogs in Los Angeles (LA) County. Most of the dogs were imported from Asia and seen by a veterinarian upon arrival into LA County. The dogs showed signs consistent with influenza such as coughing, sneezing, fever and nasal discharge. A total of 27 dogs were sick with the disease and treated with supportive care. Final testing of two dogs revealed a strain of canine influenza (H3N2) commonly found in Asia, further testing is pending. Most of the dogs have recovered.
H3N2 canine influenza usually causes mild disease in dogs and on rare occasions can also infect cats. This strain of canine influenza was first found in the US in 2015 when it caused a large outbreak in the Chicago area that spread to other parts of the country. Infected dogs start shedding the the virus 2 days before the start of clinical signs (meaning the virus was "available" to other dogs if exposed), and for 21 days or longer afterward. Transmission of influenza usually occurs through contact with infected respiratory secretions (e.g. coughing, sneezing) as well as from contamination of the environment (e.g. bedding, floors, bowls, collars, leashes).
So, what does this mean for you and your pet? The closest confirmed outbreak area that we are currently aware of is Monroe, La. As with the previous outbreaks of flu, the disease is most severe in sight hounds (Greyhounds, Whippets, Saluki, Borzois, Italian Greyhounds, Afghans etc). In these breeds it can be deadly. We recommend immunization with the new H3N2 vaccine in all these breeds as a precautionary measure.
What about in other breeds?
Flu in dogs, just like in people, tends to be exposure related. We recommend immunization for any dogs that routinely travel into endemic areas. Truck drivers, for example, who's canine companions log the same hours in the cab as they do have to stop in areas that frequently may have been exposed without their knowledge. Dogs that are shown extensively (I'm sure by now you all know our local AKC show was canceled due to this virus) need immunization protection as well. Being most careful would dictate that any geriatric patients that tend to travel would be high risk especially if they have preexisting respiratory problems (chronic tracheal collapse, congestive heart failure etc). Also hunting companions being sent to a trainer would likely benefit from immunization. Any other situation where a dog might be exposed to other dogs from parts of the country where Flu is endemic (Los Angeles, Chicago, Monroe, La, Houston, Tx, and several locations in Florida).
Currently we do not require immunization for H3N2 in order to board, have bath/dip or be groomed at our hospital. Presently we do advise immunization for dogs routinely receiving these services simply out of precaution. This is the same position we took several years ago when H3N8 was the cause of the outbreak. Eventually, that outbreak became severe enough that if clients chose to board without immunization protection, they were required to sign a release stating that they were aware of the risks were choosing not to have the vaccine.
For those of you who have participated in immunization against H3N8 in the past and have continued that practice, this vaccine does not protect against H3N2. Just like in humans, there is significant "drift and shift" in the flu virus so that vaccination against one does not protect against the other. This is the reason we were waiting to see when the bivalent vaccine from Merck would be available but currently, since no H3N8 has been isolated, we are going with just the H3N2. The protocol dictates that patients be vaccinated and then give a booster in 3 weeks.
To date, there is no evidence humans can be infected with H3N2.
We hope this helps you understand a little more clearly about the current Flu issue. We don't view this as a deadly outbreak at all! Being prudent if you have at-risk patients, however, is always the best preventive practice.
Please feel free to call our hospital with any questions you may have.
Dr. Murray, Dr. Burns, & Dr. Morgan
Westridge Animal Hospital Veterinarians
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