10 years - cat in the blossom of strength:) The problem, if it is, can be more accurately identified by a veterinary doctor. About what you described... The cat may have teeth problems and it hurts to eat dry feed.
Try to look carefully at your pet's mouth if you start to fight hard, maybe he won't let you in until you're gone because he's in pain. Let me see, look at the state of the teeth and the dess if you find something suspicious - to the wind.
I've seen one of my cats. dry feedI'm fine, I'm fine. Look at the package (food mark the same) - another manufacturer. I mean, it's possible that the feed is not exactly the same in different factories, and the cat's food from the other factory just doesn't like it. I bought the feed of the old manufacturer - eats as usual.
It's also possible to check if there's enough water in the fork and fresh water. In the wet feed, more water and if the cat lacks water, it can stop eating dry feed.
Maybe he just decided to change his tastes: Let's hope it is. Big kitty!