The rat very often indicates some people in your life that you do not feel secure being around them. The dream suggests to be aware of this fact. The rat is also something that is scary and appears in disgusting and unpleasant surroundings, so maybe you do not like this phase of your life and you should do something about it. On the positive note, the rat is good omen, because it shows your ability to adapt yourself in various situations.
Read more about dreaming of Rat in other dream meanings interpretations.