You'll have much better luck landing the cat if you rub the mouse in an attractant such as catnip. They have a hard time letting go of the fly! Make sure you use a beefy leader since they'll tend to wrap you up in some heavy cover, and some of them run BIG! You also have to watch out since sometimes a neighborhood dog will sneak up on you and try to steal your fly. They've also been known to try and steal the cat off the end of the line, just like a shark with a bonefish.
My passion for catching fish is eclipsed only by the fish's passion not to be caught.