Recap and Thoughts on Next Steps
Canine influenza, a reportable disease in Michigan, continues to be a topic of interest for Michigan companion animal veterinarians though the incidence of cases has substantially decreased since the July/August peak. As of August 31, 2018, the Michigan Department of Agriculture and Rural Development (MDARD) reported 147 confirmed cases in 12 counties. As of September 10, the case count was slightly up at 151. Most cases are in Oakland, Macomb and Kent Counties. Anecdotally, boarding kennels have been particularly hard hit. The majority of cases with strain type results have been H3N2. MDARD posts case numbers online and updates numbers periodically. You can track reported confirmed cases of canine influenza in Michigan (tracking is by number and county) on MDARD’s website.
There are a variety of educational resources available for veterinarians on canine influenza:
Overall, there is good medical information available about canine influenza. Starting with the information above can get you up to speed on the basics of disease spread, disease prevention and education for your clients. This is one of those diseases, though, where veterinarians may also benefit from thinking about population health in addition to thinking about individual patients. This is especially true when dealing with dogs that board, get groomed, attend doggy daycare and otherwise congregate and comingle, as so many of your canine patients probably do. Plus, do not forget about the triad of agent-host-environment when you look at the tools you have available to prevent and mitigate disease spread. Here are some thoughts to consider:
- Agent: Canine H3N2 is highly contagious. We should expect canine H3N2 to continue to spread in the United States with outbreaks occurring in dogs until mitigation practices become widespread and there is more widespread immunity in the dog population. Fortunately, this virus is not zoonotic; it has, though, been found in cats. The other canine influenza virus, H3N8, tends to be less contagious. H3N8 has a history of being an outbreak problem at race tracks.
- Host: “Social distancing” of dogs and vaccination are tools to protect dogs. Obviously, when dogs congregate, the virus has more opportunity to move from one dog to another. As with certain other diseases, widespread vaccination can be a major factor leading to population immunity. As noted in the recent Merck webinar, Get the Dog Flu Facts, though, vaccinating in the face of an outbreak is not particularly effective. This is because there is not enough time for a dog to complete the series of vaccinations and develop a full immune response. When deciding whether or not to routinely vaccinate a canine patient, current recommendations to evaluate the lifestyle of a pet (including opportunities for indirect contact such as dog parks or stores that allow pet visits) and vaccinate before there is an outbreak in the are reasonable. The other thing to remember about vaccination for this disease is that it does not stop infection, but it is thought to reduce shedding and result in milder clinical signs.
- Environment: The theme here is minimizing the number of virus particles and their opportunity to spread. This means preventing virus introduction, taking steps to minimize virus movement (think fomites), and cleaning and disinfecting to eliminate virus particles.
Now that the Michigan canine H3N2 outbreak appears to be diminishing, you may have some time to consider how you will deal with this disease in the future. Are there new or updated steps you can take in your practice to mitigate canine H3N2? Think about factors related to the virus, your canine patients, and the places you manage that house dogs. Veterinarians have been an integral part of curbing the recent H3N2 outbreak in Michigan and you can be even more prepared for future canine H3N2 incursions.
Nancy Frank, DVM
MVMA Staff Veterinarian