There’s a commercial out, or at least it was fairly recently, for a nifty little item called Iams Savory Sauce. This is a ketchup-style bottle of something that looks a bit like gravy, comes in bacon, chicken, and beef (though they call it Country Chicken and Homestyle Beef… as if the dog is going to know), and it’s meant to be poured over dry dog food at something like a tablespoon per half cup.