Yeah, even though dog food companies say that's when a dog becomes a senior, I don't really agree. Is your pom still active and healthy? If so, you probably really don't need to have him on a senior food. All senior foods usually do is reduce the calories, fat, and protein levels because they want us to believe for whatever reason that senior dogs don't need as many nutrients as younger dogs. This, however, is entirely false. In fact senior dogs need just as much if not more nutrition as they age, I believe that's actually the concept on which Innova Senior Plus was actually founded. They seem to have done a decent job of doing so, however it still appears as though many of their protein sources come from grains.
However, if you'd like to continue with a senior food for your dog, Innova Senior Plus is a pretty decent one. Orijen is a fantastic food. You could also do the Innova Evo reduced fat if you're worried about his metabolism. Oh and the Wellness Core is a pretty good one too. All of these foods still have some glucosamine and chondroitin in them to help maintain your pom's joints as he ages. There isn't a lot in there though, so I'm not sure how much good it will do him or if he even needs it. But it's there in case you wanted it to be.
As RFD said, you only have to worry about your protein levels when they're coming from plant-based sources. On foods like these where most of the protein comes from animal sources, dogs are made to digest those so it's not hard on their kidneys. With foods where most of the protein comes from plant sources, that's when it gets harder on their kidneys to digest it.
Good luck!
