Urinary problems occur more frequently in male dogs. If your dog is not urinating, there may be a serious underlying condition:
Urinary Stones
Urinary stones may be found in the kidneys, ureters (the tubes that carry urine from the kidneys to the bladder), urethra (the tube from the bladder to where the urine exits the body), and the bladder (the organ that holds urine). In canines, stones are usually found in the bladder. Bladder stones can get as big as 3 to 4 inches. Bladder stones are made up of different mineral compositions. Urate stones are more common in Bulldogs, Black Russian Terriers and Dalmatians. Struvite bladder stones are most commonly found in Miniature Schnauzers, Bichon Frise, Cocker Spaniels, and Miniature Poodles.
Urinary Tract Infection
Canine urinary tract infections in dogs are more common in older females and diabetic dogs. The infection causes spasms in the urethra, which then narrows the opening where urine exits the body. Urinary tract infections that are left untreated can progress into the kidneys, which can cause kidney failure and/or sepsis.
Tumor on the Urinary Tract or Bladder
A tumor is the abnormal growth of tissue creating a mass. Tumors can be benign or malignant (cancerous). A tumor on the urinary tract or bladder can cause an obstruction, which causes the inability to urinate.
Trauma
Trauma caused by vehicular contact or a fall can cause uroabdomen. The damage may cause the urine to leak into the abdomen. A canine may be unable to urinate because of the trauma to his abdominal area.
Prostate Hyperplasia
Older uncastrated males are prone to this condition. Symptoms can include blood in the urine, difficulty passing faces and difficulty passing urine.
Neurological Disease
Certain neurological diseases can mean it is hard (if not impossible) to pass urine. Passing urine requires both the relaxation and contraction of muscles.