[renegaderuby]

Yes, there are certianly alot of options. Some of which are extremely pricey.
Being that I have a bed shredder, I have seen the "insides" of many orthopedic beds, and I get miffed at how much they charge for whats basically a large peice of foam.
I finally decided that enough was enough and I purchased a ROLL of the foam (has indintations like an egg carton), from walmart, Cut it into the appropriate size, thickness (i use two peices on top of one another because ruby has a bad back)....and put them inside two zippered pillow cases.
Roll of foam : ten bucks.
Pillow case : dollar store purchase.

Wha la!

Has helped her tremendously..and when the bed shredder attacks...I just make her a new one.

PS: being that you have a big dog, I'd do the same above steps, except for instead of pillow case (which wouldnt be large enough)...get some cute print (or solid if you prefer) material off the sale rack at your local store, and just make a cover. It's fairly easy. If you cannot do it yourself...loads of seniors would "love" projects to keep them busy at assisted living facility. Just give them the measurments, and they'd likely enjoy themselves. Your pup would have a "custom" bed. and it would STILL cost half a much less than in stores.
As for washing. I just take the cases off, take it outside, poor some dish liquid on it, rinse it out with the hose, let it dry in the sun, and put the covers in the wash. Then put it back together.
It comes clean, holds no odor , and is so far durrable.