There are some double knit quilts here on QB that are really great. See if you can find them with the search feature. I would think that would make good pet blankets. Even just 2 large squares sewn pillowcase style and machine quilted would do great for the animal shelters. There is a link to a great pet bed on QB that uses fleece circles. It might work for double knits too. I used double knit to make chair cushions that I stuffed. They can be cut into strips for crocheted floor rugs.