Urinary Tract Blockage in Dogs

What Is a Urinary Tract Blockage in Dogs?

A urinary tract blockage, or obstruction, is a medical emergency that causes a dog to have difficulty urinating or to even be unable to urinate. A dog’s urinary tract includes the kidneys, ureters, bladder, and urethra, and an obstruction can be partial or complete. With an obstruction, dogs will strain and produce little to no urine.

This condition can happen in both male and female dogs, although it is more common in males because of the way their anatomy is structured. The urethra is the tube that carries urine from the bladder to be eliminated from the body. In male dogs, the urethra is longer and narrower than in females, which predisposes them to this very serious medical condition.

When dogs’ urinary tracts are obstructed, a rapid buildup of toxins occurs. If left untreated, it will lead to kidney failure and death. A urinary tract obstruction is most often caused by a stone formed in the bladder that gets stuck in the urethra, preventing urine from leaving the bladder.

Symptoms of Urinary Tract Blockage in Dogs

Clinical signs vary depending on the severity of the blockage. Dogs that have only a partial obstruction may:

• Urinate small amounts frequently

• Take a long time to be able to urinate

• Strain to urinate

• Have bloody or dark urine

• Be unable to have a steady stream of urine (urinate in drops)

• Have inappropriate urination

If the urethra is completely blocked, dogs may have:

• Straining to urinate with no urine production

• Lethargy, severe depression

• Loss of appetite

• Vomiting

• Enlargement in abdomen

It is difficult to tell the difference between a urinary tract infection and a partial obstruction, but your veterinarian will be able to determine the problem during an exam.

Both partial and complete urinary obstructions are painful and will cause a dog to vocalize when they try to urinate. They may also be restless and have trouble getting comfortable when lying down or have difficulty getting up once down. Dogs may also appear to be constipated, as straining to urinate and straining to defecate can cause the same postures.

Causes of Urinary Tract Blockage in Dogs

The most common cause of urinary tract obstructions in dogs is bladder stones (calculi) that get stuck in the urethra. Stones can also form in the kidneys and get stuck in the ureters, but this is uncommon.

Other causes of urinary obstructions can be related to muscle spasms in the urethra, inflammation (swelling) of the bladder (cystitis), mucus plugs, prostate disease in males, scar tissue, blood clots, or certain cancers. An obstruction can also occur in male dogs when the os penis (bone within the penis that the urethra passes through) is fractured or broken.

With a complete obstruction, the bladder can get so enlarged that it can rupture and spill urine into the abdomen. Dogs with complete urethral obstruction will die within days if the blockage is not relieved. Your dog should be seen by a veterinarian immediately if they are unable to urinate.

Dogs with certain medical conditions can have an increased risk of developing stones and a possible obstruction. Yorkshire Terriers and Schnauzers with liver shunts will form stones from waste not removed by the liver properly. Dalmatians have a genetic predisposition to form urate crystals. Kidney, bladder, and prostate infections can increase the risk of struvite crystals and stones forming.

How Veterinarians Diagnose Urinary Tract Blockage in Dogs

Either your dog’s veterinarian or an emergency vet will take a complete medical history and perform a full physical examination to include palpation (touching) of the urinary bladder within a dog’s abdomen. Often, a distended (enlarged) bladder and even stones in the bladder will be felt during this exam.

A rectal examination is also important to feel stones in the urethra and, in male dogs, a vet can evaluate the prostate. Full bloodwork, urinalysis, and urine culture must be done to assess the kidneys for evidence of failure and to detect an infection or crystals in the urine.

Imaging of the urinary system is important for checking if a dog has an obstruction. Plain x-rays and x-rays using contrast are very valuable to look for stones within the bladder or urethra. An ultrasound of the abdomen will also be helpful to assess the kidneys for stones or changes such as tumors, clots, or stones that do not show up on x-ray. An ultrasound can also look at the prostate in male dogs to see if it is enlarged or abnormal.

The ultimate sign of a urinary obstruction will be if a urinary catheter cannot be put from the urethra into the bladder. Most, if not all, dogs need to be sedated in order to pass a urinary catheter. Occasionally, the vet will be able to feel the stone (or other cause) with the catheter and figure out if it is a partial or complete obstruction. Your vet can place a special contrast or dye into the catheter while your dog has an x-ray done to look for narrowing of the urethra that can be associated with tumors, clots, or scar tissue.

If there is evidence that the kidneys are not functioning properly and their potassium levels are high, an ECG (electrocardiogram) should be done, as high potassium levels can cause heart problems.

Treatment of Urinary Tract Blockage in Dogs

Urinary obstruction in dogs usually requires medical treatment to stabilize them for surgery and then surgical treatment to release the obstruction. Your dog will be hospitalized with an IV catheter to receive IV fluids and pain medications. Antibiotics are needed if there is evidence of infection, and other medications can be given to help with urethral muscle spasms, inflammation, etc.

Once they are stable, a dog can be sedated and a urinary catheter will be placed into the urethra. In some obstructions caused by bladder stones, the stone can be pushed from the urethra into the bladder to relieve the obstruction. A much less complicated surgery can then be performed to remove the stone from the bladder.

If the stone cannot be passed into the bladder with the catheter or the underlying cause is not a stone, surgical removal/correction of the blockage directly from the urethra will need to be done. If any abnormal tissue is present or if a tumor is causing the obstruction, your vet will be able to take a biopsy at the time of surgery when the obstruction is resolved.

There are many different bladder stones, and some might not need surgery as they can be dissolved with a special prescription dog food diet. A cystoscope can sometimes be used to remove small stones from the bladder instead of doing surgery. 

Recovery and Management of Urinary Tract Blockage in Dogs

Dogs will need several weeks of restricted activity and wearing an Elizabethan collar (cone) after surgery to remove a urinary obstruction. After surgery on the urinary tract, blood in the urine can remain for a few weeks depending on which surgical procedure is performed.

Most urinary tract infections should be treated for a minimum of 10-14 days with antibiotics. Pain and anti-inflammatory medications are also given after the obstruction is cleared. Repeat urinalysis and urine cultures must be done after the medications are finished to be sure the infection was treated properly.

Complications of urinary obstruction include tears in the urethra or bladder, resulting in urine leakage, bladder dysfunction, incontinence, or scarring in the urethra that can cause recurrence of the obstruction.

The prognosis is good for dogs that undergo most surgical or nonsurgical procedures to relieve a urinary blockage if they have not endured significant kidney or toxic damage from a prolonged obstruction.

Prevention of Urinary Tract Blockage in Dogs

Prevention is possible in some cases of bladder stones, depending on their chemical makeup. If the stones were formed because of infection, it’s best to have routine urinalysis and urine cultures done to detect infection before the stone develops and decide if antibiotics should be prescribed. Periodic bladder x-rays or ultrasounds would also be helpful to prevent recurrence of a urinary obstruction. Early detection may allow your veterinarian to adjust your dog's diet or medications before they need surgery.