Hyenas, wolves, bears, coyotes, foxes and packs of vicious feral dogs. When the apocalypse strikes, you'll have just as much to fear from these predators as you do zombies. They're fast, sometimes ferocious, and when they're ravenous they become bolder and much more willing to attack healthy humans.
So how would these animals react to the sight and smell of the reanimated dead, which are essentially walking bags of meat? In an ecosystem ripped apart by the chaos of a zombie invasion, hunger is sure to be a challenge not just for the remaining humans but also for their animal counterparts. And like humans, those animals will do just about anything to survive, even if it means nibbling at the festering, crawling remains of what's left of someone's loved one.
Animal attacks wouldn't be limited to top-tier predators, either. Smaller animals like rats, raccoons and possums would also happily munch on undead goodies if given the opportunity — such as a legless, armless zombie sprawled in a mud pit, awaiting its final, sorrowful end.