I work and have my cars in a huge old barn. Mice are a constant problem. But then so are squirrels and dirt daubers. I do the best that I can to keep the mouse population down, but it is a constant battle. The cat thing is a non starter for us. They just kill anything and everything that they come across. When they bring the crippled baby bunnies up to the house, or kill a chipmunk, my wife cries. It is just too much for her in order for me to control the mice in the barn. So, I have to eliminate the cats and control the mice. The cats are a larger target, so they are not a problem. The wife feeds the little colored birds, and chipmunks, and bunnies. We even have flying squirrels now that the cars are gone. All that and mice, too. But no cats.