Turns out his heart is grossly enlarged (should be 30% of cavity, is now at 70%) First question vet asked was what food he was on. When we should him The Diamond Naturals grain free, he explained that he and other vets have seen a large uptick in heart problems and heart enlargement cause by grain free foods and to switch immediately.
https://www.amazon.com/Diamond-Naturals-Recipe-Natural-Caught/dp/B079FHJMMG

