Ok. The normal urination frequency in dogs varies with age and gender. A healthy dog should urinate in an interval of 5 to 8 hours. The reasons for urinary retention are many but most common are less intake of water and presence of crystals. If it's been more than 20 hours, try to feed him more water and If he still doesn't pass urine, plz get him checked thoroughly by booking a home consultation with a veterinarian.
