
I've had females go totally off their food sometimes during pregnancy (at around 4 weeks). I realise that your dog is not pregnant, but if you have had her checked, and she is in no way ill, then you might try what I did. I was really worried that my females were not getting enough nourishment (and they were both pregnant!), so I pureed their normal food, made little balls out of it, opened their mouths, put the food in, and held their mouths gently closed until they swallowed. They understood that I was not doing anything unpleasant to them (physically), and so they tolerated it, forgave me and swallowed their food. I made the food fairly wet, that seemed to help it go down. There was nothing badly wrong at all, and eventually they returned to their normal eating habits.
I've done this occasionally with my males, when they have lost their minds (and appetites) because somebody is in heat. It works. It tides everyone over until normalcy returns.