My dog seems to have gone off his dry dog food. He won’t eat it on its own but will usually eat it if mixed with a half a food can/tin of sardines/boiled fish/raw mince. But lately he is just eating around it and having all the fish/ meat/ but leaving the kibble. How can I ensure he gets all the nutrients he needs if he doesn’t eat the kibble? We have tried different brands but he eats them for a week or so and then starts to leave them.