Fridge and freezer are ONLY mouse proof if the seal is in good shape and is not easy to open. gfgbro had mice, NOT RATS, that first figured out how to push on the seal and get it to give so he found mouse poop in there. Then one apparently couldn't get out, so they chewed through the seal. It was clearly chewed from the inside out, which is how he knew they were getting in through the seal. It was his second fridge - he has one in the house, running of course, and a second running in the garage and a third that doesn't run but is kept to keep food away from the mice/rats/etc.... The one they got into was the one in the garage that ran. He has also had them gnaw through the siding of his trailer. That was rats, though. For a long time he ran off stray cats - he is allergic to them and hates that cats shed because it is "messy". Now he has figured out that if the neighbor's cats or strays are in his yard, and he is not feeding them, they they are hunting and he needs to let them be.
in my opinion you have more than one mouse. If, by some odd miracle you only have one? It is pregnant and you will have more soon. If your dog won't go after them, put out poison. You may need to try different brands or ones with different types of poison in them. the d-con ones sold at walmart here have warfarin in them. It doesn't seem to work on the ones in our area, which happens after a while. We got some other type from the farm and home store (like tractor supply, called Atwoods here, but same thing). It is a LOT cheaper to get the poison from the farm and home than from walmart. And it works a LOT better.
I have been told to put out dry, uncooked jello, that mice will eat it, then it will swell in their tummies and kill them. It doesn't work. One of the homeschool kids I know wondered about it and did an experiment wtih a mouse he caught. Mouse would have been killed in a trap or with poison anyway, and the plan was to see if it worked and if it turned out to be long and drawn out pain, then they would kill the mouse fast so it wouldn't hurt. The mouse liked the jello, over a couple of days ate an entire package and didn't even show any signs of problems. Bummer, because it would have been a lot cheaper than traps or poison, in my opinion. Around here the homeschool kids, kids in 4H and FFA do a lot of things like this - many of them do projects to try to verify wisdom from their parents or grandparents.
In an old house there ARE things you can do to keep mice away. First, they HATE peppermint. Put cottonballs with peppermint oil on them tucked into areas around the entrance of your home. Also consider planting peppermint and other mints around your home. Mint is very easy to grow and very aggressive. It will force out other plants, so be sure there is a barrier between it and any plants you want to keep. If you don't want to plant mint, put mint leaves around any area that mice might come in. Be sure all doors have draftstoppers - actually the as seen on tv ones that go under the door and have a round piece on either side of the door are great because mice can't push under them the way they can some other kinds. Be sure to put out new mint leaves every week or so, or to reapply peppermint oil. Consider using dr bronner's peppermint soap for many cleaning tasks if you like the smell. It can be used to clean almost anything, goes a long way because you dilute it greatly, is gentle and may be cheaper than buying peppermint essential oil. In a pinch, peppermint extract will work if you find it easier than essential oil.
Any holes, cracks, etc.... that mice might come in through can be filled iwth steel wool if you cannot close them otherwise for some reason (renting, can't nail somethingover it, crack in concrete, etc...) Mice hate steel wool. If they try to chew through it, the particles are like little needles inside them. If you have cracks in concrete, consider getting some of that spray can insulation that expands. Or try fix a flat - that stuff you put into a flat tire so you can continue to drive, pretty much is the insulation I was talking about, just another name and maybe easier to find.
Examine any plastic containers you buy to keep mice out of things. The plastic totes sold at stores often have holes in the handle or the rim. While very small, and maybe a mouse couldn't get in, bugs can. If you have or use those, cover the holes wtih duct tape - one piece on the inside and one on the outside. I do find that plastic totes for files, mine have a rim inside for hanging file folders, are often more airtight than the bigger ones we have.
As for mouse stories? Freckles was our best mouser. But when we lived with my folks she adopted one. She killed it's babies when they left the nest, but she would curl up with the momma and had a fit when we trapped it to get rid of it. Never understood why, but she loved that one mouse. Of course, she later became bff's with a cockatiel and she wore makeup, so she was unique!
Cats either learn to hunt during their first six weeks of life from their mother or they don't learn it. I have known a lot of cats (had a gma that we called 'Kitty Cat Gma", to give some idea of how many have been around) and have known maybe one who was a successful hunter who didn't learn it early on. Those cats born to a momma that didn't mouse? Never did learn. So if you are looking for a mouser, ask around and get a kitten from someone with a cat who is a good mouser, or has lived as a stray for a time and survived and wasn't totally starving when found. My father had a cat who would, when asked, go to the neighbor who lived across a big field from us, go into their home, deal with their mouse/mice, and then come home. All Dad did was ask him to go and "protect". Many of my parents cats would come running from the yard or even one of the nearby fields if we called "Protect momma" or "protect Susiestar". Never a hesitation, would leave other prey and come at a run. Of course, we had a labrador who would share his home with mice, squirrels, birds, etc... so I guess the cats felt they had to make up for her.
I hope you get the mice out. Remember the peppermint - it is a pretty powerful deterrent to mice, best we have found to keep them away.