So I have an old laser mouse that I use when I have the laptop out.
The other night a cat puked stomach contents all over it... nice and juicy. It sat for about half a day before I noticed it.
Took the mouse and ran it under the reverse-osmosis-filtered-water tap for about 5 minutes, periodically shaking the water around inside the mouse to (hopefully) wash all the cat puke particles off of any electronics or circuit boards.
I let it air dry for 3 days.
Plugged it in and it works fine.