The trainer I took Jimmy and Misty to recommended fasting your dog one day a week, he said it was good for flushing out their systems. I've never done it though, my dogs would make my life a misery if I did.
Stephen - once you've had Spruce checked out by the vet it might be worth trying Naturediet as recommended by Indiesnan. Prior to neutering Jimmy used to go days at a time without eating and I made the mistake of chopping and changing his food, which as others have said just makes the problem worse. Naturediet was the first food he would consistently eat on a daily basis, he'd never turn his nose up at it. Having said that though, it does seem that some dogs just don't need as much food as others and will not act or look unhealthy for it.
