I have a cat and she stays out of the way all day long and comes back after the last child leaves. However, during interviews she always comes to meet people because she is very nosy. I always ask people during my prescreening if they have any cat allergies and it even states on my website that I have a friendly cat. She's more afraid of the children than they are afraid of her, that's for sure. But in your situation I think telling all the families in your care is sufficient. They can't dictate to you whether or not you can have a pet. As long as there aren't any allergies you shouldn't have any problems.