With bowel incontinence, the bowels usually eventually move… but not with urine which a dog can retain. It is therefore important that your dog eliminate as much urine as possible from the bladder on a regular basis or he/she will risk getting a urinary infection which could, if left untreated, become a kidney infection.
You can learn to express your dogs bladder and help your pet get on a regular program for long term health. The bladder in the dog is very small so be gentle in palpating for it. The urine will flow down through the penis on a male dog so you would position your hands on either side of the flanks and start gently massaging from the top town into the direction of the proposed flow. For a female dog, the direction will be toward the back as the urine passes through the opening below the anus, therefore your intention with your gentle massage will be from the top and back toward this opening. Please ask for help from your veterinarian
See also: Bowel Expression.