This may sound nuts but with my old deaf dog Bob I do a deep bark to him to get his attention. It seems a deep bark gets his attention. He is 12 also & is on Rhimadahl & tried the aspirin but it didn't work. He also sleeps a lot & does not interact that much with the other two dogs. You are a wonderful person to take in an old dog in the winter of his life. God Bless !!!