Check out this waterproof lining. You can put soft bedding inside too to serve as your bed, if you want to DIY it a bit. Plus it makes more room in your storage spaces for dog snacks, says Mort.
Shop Dog Bedding in the Dog department at Tractor Supply Co
If you have some comforters or bedding that you need to store, you can do so inside of the bed protector and make yourself a very inexpensive dog bed that also doubles as storage. The waterproof interior will keep your bedding safe, it will be soft and comfy for your dog, and you can also make a bit of extra space in your linen closet to store other things (dogs vote for more treats).
Snoozer Pet Products Waterproof Rectangle Pet Bed
Introducing our lightest waterproof, dog-proof bedding protector ever. Constructed with two layers of fleece (one backed with a durable coating), this coverlet works hard, looks great, and boasts the same drape and weight as your favorite fleece blanket. Reverses to neutral camel color. Imported.
Snoozer Waterproof Pet Bed & Reviews | Wayfair