How would you get Polyurethane off of a kitten?

My brother was sealing up a hole under his counter and his kitten ran under the counter when he was trying to seal it up and got covered by the Polyurethane. Now the poor thing is like in a total body cast and he's tried everything from Dawn Soap to Gasoline to get it off. We're at a loss and he doesn't want it to suffer. So it's either figure a way to get this crap off or take him out in the desert and shoot the poor baby. So, do you have any life saving advice? :(