On Monday morning, one of the water bowls in a cat room at the shelter contained charcoal- gray water. There were dark gray streaks all over the commercial-grade vinyl floor of the room, and a little tabby's front paws were stained. The culprit was a black toy mouse that had been "drowned" in the water bowl, then batted around the room. Shampooing hasn't removed the stains on the cat's paws; fortunately she apparently didn't pick up the mouse in her mouth or chew on it, as there was no discoloration around her mouth or on her tongue. The streaks on the floor didn't come off with all-purpose cleaner or scouring powder. We didn't find any packaging in the trash, and nobody has owned up to giving the cats the mouse, so we have no idea what brand it was or where it was made. What if it was toxic? Just another thing to worry about.