• Things have been quiet there for a while and this seems to be a nice success story. The two flu clusters that were active in January were contained and nothing new has been seen.


  • Good progress has been made. Few new cases have been identified over the past two weeks.
  • One problematic aspect of H3N2 flu is the shedding period.  Some of the early cases in this cluster are still shedding the virus. This is a major issue because recovered dogs can look perfectly healthy but still be infectious. The duration of shedding that we’re seeing in some dogs poses a significant problem since they can be a source of infection for a long time, and it’s harder to convince people to maintain isolation when their dog looks normal.
  • We’re continuing to test and while I was a bit skeptical initially, this cluster might be controllable.


  • This area is still a concern because of the number and distribution of cases. However, there are some encouraging signs.
  • The number of new cases is decreasing. Further, the limited number of new cases that we’re seeing all have a clear link to a known case or facility. That’s good because cases of unknown origin would mean we have more unknown sources of infection out in the community. Unknown sources are a problem because we’re not able to intervene to help direct infection control measures.
  • This is the cluster that I thought might have signaled the end of any potential “search and contain” approach. However, I think we still have a chance to prevent further spread, so active surveillance is continuing.

The rest of Ontario:

  • We’re still watching.
  • It’s a challenge since there’s always some degree of “background noise” of infectious respiratory tract disease, and clusters of infections occur regularly, even when they’re not caused by flu. Some days it seems like I talk to every vet or owner of a dog in Ontario with a cough, but it’s good that there’s awareness.
  • How to conduct surveillance for a novel virus amongst a background of endemic respiratory disease is a challenge. Testing everyone that’s sick would be ideal, but isn’t possible given the available time and resources. Testing just dogs with known links to cases risks missing new clusters (as highlighted by the Muskoka and Northumberland clusters, that did not have obvious origins at the start).
  • We are continuing to test in other areas of the province, with a focus on clusters of infection, especially where there are high attack rates. For example, if 10/10 dogs in a group get sick, I’m much more concerned it’s flu than if only 2/10 get sick (even though flu would be possible in either case).
  • While we’re still trying to sort things out, testing will continue.