Sadly, you'll get mice as long as there is anything for them to eat and that includes the veggies you're growing. You might not want to mention that to her if you're planning on growing more edibles. ;) We had mice even before we had chickens... and no they weren't pets! The rats moved in when the new neighbours got a dog and fed it outdoors. They found nothing to eat in our chicken runs so they ate the cauliflowers and the apricots. We ended up having to bait them in the end as we knew we'd get the blame if they carried on multiplying.