Louie has figured out how long I will be gone based on my pants. If I put on scrub pants, he goes "no, mommy! Don't go to work!!" He then starts growling and tugging on my pants. Then he goes and sits in front of the door so that I can't open it.
If I or my husband start getting dressed in normal clothes, however, he gets really excited because he's just sure that we must be taking him wherever we are going, then he gets really sad if we don't take him, and goes to lay down on his bed. It's the saddest thing ever.