Thieves have been known to enter homes through dog and cat doors. It's amazing what they can do. At any rate, my current dogs are used to me being home. I usually leave them outside in our backyard. They love it. As I said before, though, my other dogs in the past were often left to roam the entire house anytime we left, especially when it was raining.
A number of years ago I did sometimes leave my dog with access to the (well fenced) garden, it worked fine except for two occasions, once when the neighbour had workmen up ladders at the back of the house and it made the dog bar and once when I came home to find her stuck outside wearing the dog flap - it had broken and got stuck around her body. As I did not want her to get hurt or to be a pain to others I stopped allowing her access to the garden when I was out.
I have a litter box for my Yorkie. She loves it, and goes there, when I am not at home, or if it rains or snows.
I watch her a few times with a surveillance camera. When I leave the house, she goes in her bed and sleeps, and rests,
to be ready, when I come home. Then she is full of energy when I return tired from work ;-)