Or H3N8…just not “dog flu”!
(It seems that “dog-flu” could refer to any flu-like illness in dogs due to various causes.)
From Dr. Cynda Crawford, University of Florida:
Like influenza viruses in other species, canine influenza virus causes a flu-like illness consisting of cough, sneezing and nasal discharge (”runny nose”). Fever can also occur, but it is usually transient and rarely noticed by pet owners. There are no clinical signs that distinguish canine influenza from other respiratory infections. That is why diagnostic tests must be performed to determine the cause of respiratory infections in dogs
Transmission of the virus occurs through sneezing and coughing from an infected dog and 80% of all dogs exposed to the virus become infected.
Since canine influenza is a viral infection, treatment consists mainly of supportive care while the virus runs its course, much like for human influenza.
Candidates for the vaccine would be dogs that frequent kennels or dog parks — basically the same group that requires the Bordetella shot. If your animal is a homebody, then there is probably no need for this vaccacine.
More info here.