I just went back and read your last post because I had missed it. Poor pup! I'm glad she's doing better. When Dexter started having trouble with the stairs, I bought a pack of cheap carpet treads at Home Depot. They were not even remotely pretty, but they were like $10 or $15 and totally did the trick. My plan was if the cheapies worked, I would replace them with FLOR tiles cut to fit, or something a bit nicer looking, but I never got around to it.
ETA: I had to use carpet tape to secure them to the stairs, which I was worried about because we have wood floors too. But it only took four tiny dots of tape, one in each corner, and when we removed them, the adhesive came off without leaving any damage. It took some goo-gone and a bit of careful scraping with a plastic scraper, but the wood was unharmed.
I keep an old yoga mat under our dog's bed because she likes to nest and I don't want her to scratch the hardwood floor. It's not the prettiest solution but does provide good traction and grip. I remove the yoga mats when we have visitors.