Cotton the dog

A week ago I accidentally came across this magazine article which says that dogs can get depression. As to whether it dies I am not sure. I wish that somebody can help me solve this problem. I just don't want Cotton to have depression. It is just that he sometimes lie flat on the marble floor which seem to me his cutest pose. Other times he will just stick close to the house door as though he want to run and escape. Most importantly he doesn't move. I like him in the way he move then I know he is okay.