Frequent mutation is part of the reason the virus could also move to humans. A dog living in close quarters with his owner might have just the one strain of the mutated virus that could take hold in humans. But the flu has another scary quality that may help it make the jump: The flu not only mutates, but can jumble up the order of its genes, like a game of genetic Boggle. “So, hypothetically, you could have a dog with H3N2 [a different strain of canine flu], and the owner of that dog could have H1N1 [which started in swine]. If the owner sneezes on the dog, then the dog could get a dual infection, and out of that could come something truly nasty,” Dubovi says.