Water-repellent fabrics such as ripstop nylon, polyester, softshell as well as waterproof fabrics such as polyester with PVC coating or nylon with PU coating are best for a dog cover for outdoor.
When sewing a dog blanket, it is important that the chosen fabric is easy to clean and durable. Pay attention to the washing instructions of the fabric and choose one that is machine washable to make cleaning easier. You can also use waterproof materials or a water-repellent coating if needed to ensure the blanket is waterproof.