[StriperSS]

I've used instant mashed potato flakes with good results. Put them down in little piles, and just leave them. The mice think it's great that you're feeding them, and you are. Their problems start when they need a drink. They swell up and die, as they are unable to regurgitate.
It does work. I had a packrat in the shed, and he ate some of what I provided. He's definitely gone.
Dogs and cats aren't affected.