You can use rubbing alcohol to take blue kote off. You'll still have to scrub it lot, but it helps to take it off of skin.
Poor old brood mare casted herself in the stall yesterday morning because she was colicly. got the alert on that at 6 in the morning and then it was a long morning of walking her around the arena and holding her for the vet. Good news is that she did just poop when I checked in on her about 12:15 tonight.