He came through the garage door while we were parking our car... And BAM, instant friends! It's just too cute. We went to walk him out to try to find if he was lost, but he was full of fleas and we found out later he had no microchip so it's just a regular abandoned dog.
We brought him inside, gave him a bath and here he is in the veterinary for the anti-flea treatment. They'll keep him for 24h, so we need to find an owner quickly, because having two cats in a small apartment leaves no space for a little cute dog...