I need help identifying a science fiction short story about a space ship landing on a planet. The astronauts turn out to be cats and the planet is earth. They are unable to communicate with the natives (humans), who just want to pet them and take care of them. That's how we got domesticated cats.
You may be thinking of Some Are Born Cats, by Terry and Carol Carr. First published in 1973 and included in the popular Magicats! anthology in 1984.
After getting in injection of sodium pentathol (truth serum) at the vet's, the cat Gilgamesh confesses that he was sent to Earth to capture George, another cat, who is an escaped criminal. Both cats are really shapeshifting aliens.
“Not really, of course, because really he’s an alien shape-changing amoeba from Procyon. And worse than that, remember what Gilgamesh said, he’s a runaway. He’s a dropout from interstellar society. Who knows, maybe he even uses drugs!”
Alyson rested a level gaze on Freddie, a patient, forgiving look. “Freddie,” she said softly, “some of us are born cats, and some of us achieve catness.”
“Well, look, if you were an amoeba from Procyon and you were sent off to the work camps, wouldn’t you rather come to Earth and be a cat and lie around all day sunning yourself and getting scratched behind the ears? I mean, it just makes sense. It proves George is sane!”
“It proves he’s lazy,” Freddie muttered.