According to New Jersey's American Animal Hospital, a dog can go for 8 to 10 hours without urinating. This varies somewhat depending upon the individual dog and the amount of salt and sugar the animal has consumed.
On Cesar's Way, dog trainer Cesar Millan's site, a veterinarian describes other circumstances that affect dogs' urinary output. When dogs have reduced activity, such as on long car trips, or when they are excited or distracted, they urinate less often. Cesar's Way reports that a dog's age, sex, size and health impact the frequency of urination; however, on average, for every pound of body weight, a dog generates 10 to 20 milliliters of urine daily.