Animals that walk on two legs are bipedal. So while you're bipedal, your cat is not.
Bipedal animals include humans, ostriches, and gibbons. Many others are known as optional bipeds, meaning they're bipedal some of the time and walk on all four legs at other times. Apes, kangaroos, and bears are occasionally bipedal — and your little dog might be too, if she's very well trained. This word comes from the roots bi-,"two," and ped, "foot."