On a cat, why not? Cats have the sass to pull that kind of wacky thing off :P
But I do think it'd be nicer if she had a full name (
Leopoldine, or
Leontine, or
Leonie or something) which had
Leo as a nn. In fact, I think that's kind of cute in a GP-fashion on a
person, so if I saw it on a cat I'd probably have kittens... metaphorical ones, of course.