There is no such thing as ONE rat. And, rats WILL get into your house if they decide to do so.

Years ago, I talked to a "rat guy" who told me a number of stories. One awed me. Next to the hole through the 200mm thick concrete wall were several hundred rat carcasses. He said they died gnawing the wall to get into a large cattle barn. Wore their teeth down and bled to death, all for the common goal.

He told the owner to keep all the cattle in the pasture for four nights in a row. On the fourth night, he plugged the hole an hour before dawn. He had reversed a vent fan and hooked up an exhaust hose to his truck tailpipe. It took two days to remove over 5000 rats from the barn.

Terminate the rodent with extreme predjudice.