Older dog and appropriate diet-do not believe in the quality of granules.

Hello. I want to ask. In older dogs Jack Russel over 10 years, how often would you combine granules, cooked meat with side dish and vegetables and fruits with something dairy? It came to me as the best combination most often give meat, offal + vegetables and side dish, sometimes the granules themselves and quite rarely need white yoghurt with black fruit. I don't want to feed him just granules, I don't trust them. Thanks for the feedback. PS: when my dog occasionally knock legs but not winter what it can be that muscles weaken ??? Thank you for comments.