we used rat poison blocks, blue in colour. We haven't seen a rat in nearly 2 yrs so it must have done the trick.
If you have dogs you have to make sure to put the poison in a safe place. The trick with rat poison is put loads of blocks down for them and wait to see what happens. Too little amount of blocks and the rats become immune to the poison, too many and you'll have to go around picking the leftover blocks up. Hope this helps
Thanks