Happy to hear that Millie is eating better. I think food tends to take around twelve hours to go through my dogs system. I am going by when it is obvious what food in, equals stools out. EG stools contains some corn or other less digestible things. However I think that, if there is a adverse reaction, the body can take less time to get the offending food out. I sure it can vary. My dog has taken in too much sea water before and it was expelled within 10 minutes!