As I am currently disabled with my right hand, the tube squeezer that I described at the end of May 2013 and in June 2014 ((C&T tube squeezer, no longer on Migipedia) is also used to squeeze out the cat food bags.
Otherwise, the rest is squeezed out by hand and the bags are washed and disposed of. The squeezed bags are then stored unwashed in an empty bag of chips and later added to the garbage bag.
It's easier than laboriously putting on a glove or changing the bandage, as it is not water-resistant!