What is canine influenza (H3N2)?

Canine influenza (H3N2), more commonly known as dog flu, is an avian influenza virus (bird flu) that spread to dogs in Asia in the mid 2000s and more widely in some parts of the region, particularly China and South Korea. It was introduced to the United States in 2015, and has spread to multiple parts of that country. The first known canine influenza case in Canada was reported in early 2018, when two dogs who were imported from Asia to Essex County, Ontario, were diagnosed. As of Spring 2018, there have been clusters of flu outbreak in Windsor-Essex, Muskoka and Northumberland County, with an estimated 200 Canadian dogs infected with the virus as of late March.

As of late April, the clusters above have been inactive and there has been no other known canine influenza activity in Canada. Experts are holding off saying “it’s gone” but based on all the information available at the moment, there’s no evidence of ongoing canine flu activity in Canada, at least for now. However, we presumably haven’t seen the last of canine flu and continued vigilance is warranted.

UPDATE: October 2018 An outbreak of Canine Influenza has occurred in Muskoka. As of now, the outbreak appears to be contained to approximately 20 dogs but is not over. Continued vigilance is required.

UPDATE As of December 3rd 2018: The most recent outbreak is considered over and once again Canada is Canine Influenza free…for now. Continued vigilance is required as always.  

Influenza in dogs has many similarities to influenza in people. Most affected dogs develop typical flu-like signs such as coughing, fever and runny nose or eyes. While most dogs (like most people with human flu) recover uneventfully, a small percentage of dogs can develop serious, and even fatal disease.

How to protect your dog from canine influenza:

• If your dog is sick, keep it away from other dogs.

• If you are out with your dog and see a sick dog, keep your dog away from it.

• If you have contact with a sick dog, wash your hands, and ideally change your clothes, before you touch your dog.

• Most dogs with influenza get over it on their own. As long as they are bright, alert, eating and don’t have yellowish nasal discharge, veterinarians typically do not provide any specific treatments beyond cough suppressants, if coughing is excessive.

• If your dog has signs that could be consistent with influenza (e.g. cough, nasal discharge, fever, runny nose or eyes) and you are taking it to your veterinarian, make sure you call the veterinary hospital first so that they can use measures to prevent exposure of other dogs at the clinic (e.g. admitting your dog directly to an exam room or isolation area).

• If your dog is sick and has been at a kennel, doggy daycare, puppy class or any other event, contact the owner or operator to let them know.

• If your dog is diagnosed with influenza or has signs consistent with influenza, it should be kept away from other dogs for four weeks, even if appears to be healthy before the end of that period. Some dogs can continue to shed the flu virus for a couple of weeks after they recover.

• Canine influenza can infect cats, but the incidence appears to be very low.

• Vaccination is not a guarantee, but it can reduce the likelihood and severity of disease.


What dogs should be consider for vaccination?

·         Dogs that will be travelling to areas in the US where there is canine flu activity (or more broadly, dogs that travel to the US, since canine flu is present in various regions).

·         Dogs that may have contact with dogs imported from Asia. This includes mainly dogs in rescues and kennels that are actively importing dogs, as well as dogs in households of people thinking about adopting a dog from Asia.

·         Dogs that may have contact with dogs imported (or travelling) from the US. The risk here is lower, but if dogs are coming from US shelters, in particular, it’s not a bad idea to vaccinate the dogs that will have contact with them.

·         Dogs at increased risk of exposure: This includes dogs that have frequent contact with lots of other dogs, especially dogs from a wide geographic range, such as those that travel for shows or other similar events. This also includes coming into contact with lots of other dogs of unknown travel or exposure history.

·         Dogs at increased risk of serious consequences. This includes dogs with pre-existing heart disease or lung disease, potential senior dogs, and brachycephalic breeds (i.e. smushy faced dogs like bulldogs).


What about everyone else?

On one hand, it’s easy to say that the risk of exposure is very low, so vaccination is of very low utility (because it’s true). The tricky part is the fact that you never know when (and it’s probably when, not if) canine flu will revisit Canada. It takes two doses of vaccine given a couple of weeks apart for good vaccine effectiveness, so by the time a problem is identified, dogs in the immediate area may already be exposed before vaccination has time to work.

Canine flu could pop up in any given city tomorrow, but it also might not happen for years. At the moment, it’s hard to say that vaccination is broadly indicated in Canadian dogs, but if you are particularly worried about flu, it’s a safe vaccine and there’s no reason not to get it.


If you have any questions about canine influenza or about your pet’s risk of contracting canine influenza, please contact the hospital.