I have a cat, he is worthless so far when it comes to mice. We’re still trying to get him out of hiding in the upstairs bedroom.
I was hoping the smell of cat would make the mice leave, no luck there.
You might also have ductwork in your attic and or walls.
Depending on how many mice you think you have and how often you think they’re coming in, you should probably consider trapping them (instead of poisoning them and not knowing where they’ll die). Personally, I’m a big fan of the large plastic (for rats) snap traps. Like this. I step on the back with my foot while baiting it and I learned (from my Orkin guy) that it works best to bait it with something sticky like a Milky Way or Snickers Bar. Using peanut butter butter doesn’t work that well, they can reach in and lick it out, you need something that they have to get in there and gnaw at.
However, with a can roaming around, I’d find something safer, either a homemade type one like the one mentioned above (or one of the million variations of it), a live trap or one of the types where the snap mechanism is internal so it’s safer. These ones will break your foot if you step in it.
On the other hand, I’ve set them in my garage and had mice grab the bait within minutes.
I’ve been using a similar trap, baiting it with pieces of reeses cup. It doesn’t take long to get one.
I set them along the baseboards and put a box in front of them to keep the dog from accidentally stepping on one. He’s so blind and deaf, he never gets into anything. The cat is still hiding most of the time so I’m not worried about him getting into the traps yet. I’m slowly getting him downstairs. I doubt if a peanut butter cup will attract him anyway.
I resisted using sticky traps because they are cruel, but this is war and I don’t care anymore.
KCB I’m going to look into something like that for inside the shed.