Monday night, July 27, a webinar was held providing the latest news on canine influenza with three expert veterinarians – one from Cornell, one from University of Wisconsin and one from Merck. The webinar started by tracing the history of the latest canine influenza outbreak this spring from the first cases in Chicago in March to Atlanta in late June and now sporadic cases showing up in South and North Carolina, New York, New Jersey, California, Idaho and South Dakota.
The detective work to discover this was the “new” canine influenza of the H3N2 type was a true show of collaboration and some intuitive guesswork by veterinarians from the Animal Health Diagnostic Laboratory at Cornell, the National Animal Disease Center lab at Ames, Iowa and the University of Wisconsin labs. Isolating the virus has required some new methods for sample shipments – cotton swabs with wooden shafts cannot be used. Samples must be on ice and with plastic swabs.
There are similarities between this new influenza virus and the better known version called H3N8. Both cause respiratory illness. Both have high rates of morbidity – meaning virtually all dogs who are exposed will be infected, with upwards of 80 percent showing some signs of illness. Mortality rate is around 8 percent. Outbreaks tend to start with dogs who are out and about. In Atlanta that meant dogs going to doggie daycare. In Chicago, it meant shelters with public dog facilities such as training facilities attached.
The viruses are easy to kill with common disinfectants but also easy to spread. A coughing or sneezing dog can shed the virus and people can spread the virus via their clothes, hands and shoes. Isolation is important to stop the spread of these illnesses. Care is primarily supportive since these are viral diseases.
There are important differences. H3N2 can infect cats as well as dogs. At least two positive cases in felines have been isolated. So far no human cases have been detected. Dogs with this version are more likely to have high fevers and a thick nasal discharge. One of the biggest differences is that dogs can shed the H3N2 virus for up to three weeks after infection. That means isolation must last that long. Some dogs will cough for up to 60 days with a dry, rasping cough.
There is no vaccine presently for the H3N2 version of canine influenza but researchers suspect there may be some slight protection from the H3N8 vaccine. Dogs who have been vaccinated for H3N8 and then get exposed to the H3N2 will have a high spike in their titers. It is important to remember that canine flu vaccines, like human flu vaccines, are not great at totally preventing illness. What they tend to do is reduce the severity of symptoms and the duration of the illness. Researchers stressed that if you decide to use the canine influenza vaccine, dogs will initially need two doses. The second one must be given in two to four weeks to stimulate a proper response.
Canine influenza is clearly here to stay. Eventually many dogs will have been exposed and developed some immunity. If there is an outbreak in your area, isolate your dogs – stop training classes and doggie daycare visits. This is especially important if your dog shows any signs of illness. Discuss vaccination with your veterinarian. While many dogs will get ill, most recover completely.