We have a Cavachon, Cavalier/Bichon cross. We keep being told he is heavy and he shouldn't put on any more weight. He gets a small tub of wet food in the morning and three quarters of a cup of dry food in the afternoon. He is not a greedy dog, he doesn't look for food and he doesn't beg. He weighs about two stone. How can we reduce his weight. We take him to the beach a couple of times a week where he runs free and he gets a long walk in the evening and a shorter walk in the morning.