Quote - When my cat Florence was getting in years and couldnt deal as easily with the litter box as she might, my vet recommended something whose name I forget, but it came in a tube. You put a bit of it on your finger, and the cat licks it off -- apparently, to them, it's pretty tasty, and it works as a digestive. I'll dig around in the old vet records and see if I can find what it was. It might help.

Maybe it's the hairball remedy that I mentioned?  It comes in a tube and kitty just licks it off of your finger.  It helps, well, lubricate the insides.    It helps to move the obstruction of the hairball through the intestines so they don't have to throw up instead.  Some of them have petroleum products in them, but I bought one, Natural Defense by Sentry, that doesn't have any of those products in it.