There is a new flu virus going around. It initially looked quite lethal, and caused panic. Now it is clear that it has killed relatively few victims — and many of those have underlying conditions. It is particularly dangerous to be the possessor of a pushed-in nose — that is, to be a Pekingese, a pug or a Shi-Tzu. It is the H3N8 dog flu. The virus, scientists believe, jumped from horses to dogs at least five years ago, but it has never infected a human.