I have the same issue with a neighbours cats...They come in through the dog door in the early hours of the morning to eat my dogs biscuits. I remove the biscuits at night now, but this doesn't stop them from coming in, snooping about, and whizzing all over my beautiful rugs.I am sure if my Jack Russell's had free reign on her property whenever they wanted my neighbour would most certainly have something to say about it. My Jacls have taken them on late at night a few times...but invariably come off second best with sore scratched noses.