I agree with Marianne about doing a test soak,it will also give you a good idea about the quality of your food. The foods with good ingredients dont tend to swell up at all,,where as the lesser foods tend to swell up to sizes quite a bit larger then when they were dry :(
I did this test with my food,berrimans, and a number of supermarket brands of questionable quality,my dry didnt change shape at ALL,the other brands swelled up considerably! The thing is,most people dont think to soak their dogs food and most people feed these supermarket brands :( I wonder how many cases of bloat and goodness knows what other digestive conditions can be attributed to this?