Several years ago, I asked my mother-in-law to make me a couple of giant pillow cases (with the interior flap to hold pillows in) that I could stuff old bed pillows in and use for beds for Chewy and Anya. Three years later, we have four of these beds throughout our house and they are the best. All of our babies use them on a daily basis and they are easy to move around and clean.
Awhile back, I noticed that Chewy had begun to experience some old-lady incontinence and that I needed to wash the beds in their crates a lot more frequently. I knew there had to be a better way to do this; washing and drying bed pillows gets old fast. I threw away the old pillows a few weeks ago, cut a twin-size foam egg crate mattress pad into thirds, and purchased a couple of inexpensive waterproof crib mattress covers. When I was brainstorming ways to protect the foam, Kyle actually thought of the crib mattress protectors. Smart man!
Wah-lah! New and improved dog beds with waterproof protection over the interior bed. I used two of the thirds and made a super thick bed for the crate Chewy sleeps in most of the time and the other third for a regular thickness bed for Anya. Now all I have to wash is the fleece case and protective liner. While the crib mattress protector works for big dog beds, I am sure you could use the smaller waterproof crib pads or liners for smaller dog and cat beds. We have to get creative with our special needs babies and this is just another way we handle business in our house. Maybe this will be useful for you too!