What is the padlock used for?

[Shift]

Hmm... I noticed this too and I quite agree with Kedjane: It must be for the later episodes. The only other explination is that its some sick joke to get us obsessed with guessing what its for...

An intresting (off-topic) point though, is that at one point in the game, when I put the dog in the cage, closed the door and turned on the steam the dog was still able to tackle the door down and attack me. Strange. Any one else experience this?