My 18 month old cocker often only has one wee a day. He used to go out after breakfast but hardly ever wants to now. He saves it until walkies time at about 5 and then has an enormous one! Doesn't want to go out before bed either. This doesn't seem right to me. He doesn't drink very much in the house and he is fed on a mixture of canned food and Fish 4 Dogs. He seems healthy and active so should I be worried?