We had this big hound that had to wear a cone for a while (see my avatar). My daughter taped a Cherio the the inside edge juuuussst out of reach. We had to mop up the drool puddles, but it was funny.
Our little Jack was in the early stages of renal failure when he passed. Special food kept his pretty much in check until the cancer got him. Good luck with Rosie.
Hoping the change in food helps her out, vet sent us home with Royal Canin Renal formula. She's acting 100% normal, walk every day, chases the ball, doesn't act like she's suffering at all just backed right off on eating and has lost some weight.