Well, first I have to tell you something. Miniature Schnauzers
were meant for ratting, or to kill rats. Well obviously the rat
will die but your Miniature Schnauzer will be fine.
--- As an addendum to the point above, your Miniature Schnauzer
may not be fine - rats may be rife with bacteria and disease, which
your Schnauzer may not be used to. If your Schnauzer has bit a rat,
it may be an idea to discuss it with your vet, as the bacteria
could cause your Schnauzer to get sick.