i was having the same problem with one of my babies...she would be excited about a food for about.....10 seconds

... tried so many kinds, tried adding canned to it, tried adding low sodium broth to it, tried adding yogurt, tried adding cottage cheese, etc etc etc...she is just a BOOGER!
now i have her back on raw and she will eat it everytime...sometimes i think she holds out for a few seconds for a different flavor

but within a minute, she eats it all...it is challenging finding something that our picky kids will eat, but keep plugging away...and remember, dogs WILL eat when they get hungry enough...i just think they are too smart for their own good and try and hold out so mommy or daddy will feel bad for them and give in