[bryanlarsen]

Only a desperate cat would take on a rat. They're big and mean. Sure, the cat can kill the rat, but the chance of significant injury would be high. And in the wild a significant injury is often a death sentence.

The title really misleads -- cats can be great at urban mouse control. But for urban rat control you need something bigger.

[pseudohadamard]

The methodology is a bit biased, if you have a rat problem you get a farm cat to deal with it, you don't hope some half-starved possibly sick or injured feral happens to turn up and get rid of them.

[bryanlarsen]

My comment was written using personal experience with farm cats.