We have 2 Yorkie Terriers and have had them for approx 4 years now. They are fully house trained - we have a cat-flap in the back door and they come and go as they please, to go outside and do their business whenever they need.
This is fine when we're at home. However, when we're out (we both work full time), one, or poss both of them, pee on the kitchen floor and conservatory floor. This is VERY annoying, as the cat-flap is only a few feet away.
It seems that when we're out, they protest and pee in the house, so now when we go out, they go into a cage - a decent size one with plenty of room for both of them. My missus always comes home at dinner time, so they're never left for more than a few hours at a time.
We've tried several imes of leaving them and letting them have the run of the house downstairs. They might go a few days, then one of them pees on the floor, so back in the cage they go. They NEVER pee in the house when we're home, so we reckon it's a protest at being left alone.
They seem quite happy going into the cage - when the last person is leaving the house they automatically go into the cage, waiting for us to shut the door on them. It might seem a bit cruel, but we got fed up of them peeing on my floor......