Do dogs know when their full?

Dogs normally stop eating when they have had enough. My dog gets his bowl put down twice a day - breakfast and dinner. Some times he just sniffs it and walks away and sometimes he tucks in! but as soon as he's walked away from the bowl i i tidy it away - so that he can't just help himself whenever he feels like it! its supposed to be good for training too - the fact that you're the 'master' and you decide when to give him his food hope that helps! k http://www.terrierdogs.co.uk