Take a look at this place: k9ballistics.com/ This place advertises as having a chew proof bed. You could look into it and see if there is a guarantee. You can also look up ballistic or high denier nylon and make a slip cover for you bed. You can order the raw material. I can attest to the strength of this type of material. I have water proof horse blankets that are either 1200 or 1600 denier and they run through the woods and hit stubs with them, lay on them, and they pull on each others. These have held up extremely well with little damage. I think it's really worth a try.
Like another poster said, though, your dogs nails are probably too long. This can happen even trimming them every week if you aren't aggressive enough. It's a fine line, but as the nail grow out, so does the quick. If you trim the nails back to near the quick, it'll die back and you can trim it back further. I have a Jack Russell and she used to be so active I only had to trim her nails a couple of times a year. Almost a year ago, I noticed that they'd grown out, because she was slowing with age and were actually turning her toes slightly. I started right away, trimming them back to near the quick every week. It took several months, but I finally got them to where she's silent when she walks across the floors. I would have noticed sooner, but she's mostly an outside dog so I don't hear it. You have to get near the quick without hitting it. Like I said, it's a slow process. It took me months to work the quick back less than a quarter of an inch.
It's worth it, though. If your dogs nails are long enough that you hear them walk, then they're putting stress on the toes. This causes the dog to rock back on their heels, stressing the leg and causing discomfort, pain, and arthritis. I noticed a definite change in how she runs around from when they were too long to when I got them cut back to a reasonable length. Now that they're where I want them, I use a dremel sander to keep them there. That is more comfortable for her as well as rounding them nicely so that they don't scratch the floors. Good luck.