You can put frozen water bottles in their cage, or if it's really hot, ice cubes or blocks. I also put the fan on, like myspoiltpiggies said. One other thing, you can buy ceramic tiles at a store like Home Depot, or a craft store, and put it their cage. The tiles get cool easily, and the pigs like to lay on them to cool down. My Queenie is so funny. She stretches out and lays on her back in the middle of the tile, her arms and legs up in the air. They really enjoy them!