A little late to the conversation

our approach has always been, if he eats it let them they will eat what they feel they need to. When our big guy Timber was sick, we gave them anything he was interested in. They know more about what they need than we do.
Years ago, i picked up this very skinny cat, Leo, who after I purchased him found out he only had 4 teeth. For the first few months we had him, he ate wet cat food and slept. And that was it. I remember we had just gone out to buy 20 something packages for him. He walked up to the hard cat food and started eating it. He completely stopped eating the wet food, which we had to take back :)
We did the samething with our dog. She would only eat meatballs (homemade) meatloaf and ginger snaps. So that's what she got!
Good luck!