Kirsten, you are not alone in your fears!!! I do a head count at bedtime for all 8 cats. I have signs on doors to alert people that these are indoor cats and they DO NOT GO OUT despite how they might behave!! We recently had the township tax reassessor at the house. He WAS told about the cats and to close doors quickly. As he was leaving, he was talking with the kitchen door open. and Norton took advantage and flew down the steps to the basement!!! I inform workmen, telephone repairers, EVERYONE that we have cats and if they are in my house doing work, they, too, are responsible for the safety of the cats. Most are cat folk and understand completely! My greatest fear was when we were on vacation on Cape Cod. I was so afraid that one of the cats would get out. We would still be on Cape Cod if that was the case!!!
Sometimes when Barry and I go out, I put treats down for each cat on the floor. They are so busy eating that they do not notice us leaving.
Our fault is we love our cats and would not want anything to happen to them!!!
PS: One fear is that if someone breaks into the house and leaves a door or window open....you know what will happen....All have breakaway collars with ID's and are microchipped(still my mind does not rest easy)...