I breed bunnies, and find a piece of wet thick carpet in the bottom of the cage is the best way to stop heat stroke. Sometimes the ice bricks themselves can make them go into shock, so should be wrapped in a towel first. I also put ice cubes in the water dish (which is much better than those bottles that hang because they get really hot in summer and freeze in winter). I also dip old towels in water and drape them over the cage with the ends on either side dangling in full buckets of water so the water can wick up and over the towel. I also provide a piece of wet carpet for the dog, so I'm sure it will work for pigs too.