I had one with sore gums in his later years. I had him on the antibiotic off and on for years. It takes awhile before they stop expecting pain when they eat, I think.

It gets hard as they age to keep weight on. Kidney function is always one of the first things to go in my experience. My older cats get warm water on their dry food and when that is absorbed, I stir in canned. It keeps them full longer and I do that at least twice a day. I have two 17 1/2 years olds that are getting that now.