I tried to walk on the ground by some rats in mission two.

never had a problem with rats in low chaos.

I did enough maiming to kill a lot of rats. they just keep respawning it seems. I reloaded, thew a corpse near them so they would be nearer guards, and then I watched this pack of rats kill 5 guards. can't remember which save I eventually went with, but it seemed like near that place in mission two (no spoilers) those rats had infinite respawn.

does that happen in high chaos? because that will definitely effect how I deal with rat packs.