Thanks for the information. The reason I'm asking is because I'm hoping we can put some kind of cover on the couch to protect it from dirty dog feet and it would be nice if it stayed in place over the back. I know it's normally pretty tight behind the couch though.
What worked out best for us was a thick comforter that we had no attachment to. We just bought it for the dog, wet feet and all and because it's thick nothing gets through to the sofa ( at least not yet) and she's still cleaner than the grandkids.
We're using an old blanket on our sofa also. We looked for a cover but couldn't find one reasonable. The blanket stays put for the most part until the dog covers herself with it if she can.