Jimmy Fallon just mentioned an outbreak of the dog flu (canine influenza virus) in New York City. He says, "You can avoid it by having your dogs drink from the toilet."
Not sure of that Jimmy - but a vaccine works.
There are outbreaks of this very contagious around the country. If you're traveling, find out (ask your veterinarian), if the canine influenza is 'hot' wherever you're going. If so, the vaccine (which includes a booster - so plan in advance) may be a very good idea. For example, the virus is has been rampant this year in and around Hartford, CT and San Antonio, TX. Here's a recent story I wrote about the canine influenza virus.