We have a lot of mice for some reason. Our cat would always carry it around the house in her mouth until she found either my wife or I and then drop it at our feet.
I trained the cat to follow me with it in her mouth and then drop it in the toilet. (She is an indoor kitty so that's why she can't bring it outside.)
A little inhumane? I guess but it gets the job done! I love my smart kitty!