Another, bigger, zombie apocalypse. ALL dead creatures revive to eat the living. I don't see any happy endings here.
The zombie apocalypse has, as far as I know, mostly been confined to human corpses reviving. I've heard of one novel, and a video game or two, that had zombie dogs. But why should revival occur in just man and pooch? Why not all animals with a central nervous system? Zombie dogs, zombie cats, zombie cows, zombie salmon, zombie sharks, zombie sparrows, zombie hawks, zombie rats, zombie alligators, zombie snakes, zombie bats. Humanity would be so screwed.
God help us if ALL animals came back from the dead. How do you rekill a zombie cockroach?
(Suggested by Daniel Peace)