I think your friend will be tickled pink that you want to make something for her dogs. We have always had dogs and they do become like family. My husband and I joke that now that our human kids are grown, the five four legged animals that share our lives are like our "kids" (3 dogs, 2 cats).
I've made several square boxy style beds that my dogs love. Our pups are getting up there in age so I used what was left of a memory foam bed pad my daughter's dog chewed on and made covers with zippers so they are easily removed and washed.
Our middle pup has adopted the couch (with blanket, of course) as hers. When she was having difficulties with her knee I made her a "floor couch (I think it was a McCalls sewing pattern) so she wouldn't have to jump and they all love it. My oldest will lay on anything that "smells" of us as long as it is near me.
What ever you choose, use sturdy materials and as someone suggested, extra space in the seam allowance. It probably goes without saying the make sure it is easily washable (fabric & size wise). Have fun!