I am afraid I'm causing a gender and species identity crisis in two miniature poodles. I have two male cats, but I dogsit for two female poodles. I often catch myself saying to the dogs "Are you being good kitties today?" Or "C'mon boys, time to go outside".
They always seem happy no matter what, so perhaps the damage is minimal!

I never get my cats confused with the dogs, however. Of course, my cats seldom answer to anything I say - after all, they are cats!