Many years ago, I saw an episode of a show that I don't remember the name of, the episode was about a family that was dealing with a giant rat. The rat lived in the walls and beneath their house, it killed their cat. The family called in an expert, and then afterwards the expert tried to tell them about a family of large rats, but the husband cuts him off, saying if its rats then they can handle it. Does this ring a bell with anyone.

Possibly the fourth segment from the movie Nighmares, Night of the Rat. Nightmares (http://en.wikipedia.org/wiki/Nightmares_%281983_film%29)