To dream of rats denotes that you will be deceived and injured by your neighbors. Quarrels with your companions is also foreboded.
To catch rats means you will scorn the baseness of others and worthily outstrip your enemies.
To kill one denotes your victory in any contest.
Non - threatening: Indicates that something doesn't make sense, is deceptive, is wrong or amiss, isn't fair.
Threatening or attacking you: you are in the midst of a situation that involves the previously mentioned meanings. May represent disease if the dream is one about health or well being.
A rat, or rats, in your dream points up the fact that someone is very jealous of you and/or your accomplishments and will work against you in any way possible, it is a dream of warning to be on the alert for enemy attack, (the backbiting kind). If you see a white rat it means the same but you will have help from unknown forces. To hear rats running, or gnawing in the walls, shows that you have been wasting your time and should move on to greener pastures.
Sickness of an epidemic nature is foretold by a dream of rats. It is a warning to avoid crowds and to guard your health.