I never had a specific live-action animal hero that I liked in my childhood, just animated ones like Mighty Mouse and Underdog ("There's no need to fear,Underdog is here.") My daughter's favorite animated animal hero is Sonic the Hedgehog -the blue blur. the fastest thing alive.
As far as live action animal heroes go, I just cry like an idiot when they air those Animal Planet segments about dogs that save human lives by licking a human's face to keep them conscious ,or animals that save other animals ,like the cat that adopted puppies and nursed them when their mother was stolen.