Bladder Stones in Dogs

Kelly Roper
Vet examining a Bulldog

Bladder stones in dogs present just as serious a condition as they do in people. Learn about different types of stones, what causes them and how veterinarians treat them. There are even a few things you can do at home to help prevent your dog from forming certain types of stones.

About Bladder Stones in Dogs

Bladder stones are referred to by several other names, including uroliths and urinary calculi. A stone starts out as a tiny mineral crystal that forms in a dog's urine. In some cases the crystal will dissolve without ever causing an issue. In other cases, a single crystal may become fused with others, solidify and continue to grow even larger. Stone sizes can range from extremely small to several inches in diameter.

Although the majority of stones in dogs are often found in the bladder, they can also be found in a dog's kidneys, ureters or urethra depending on where they were first formed and how far they have traveled in the dog's urinary system before they were detected.

The most common types of stones dogs get are:

  • Struvite stones - These stones are composed of magnesium ammonium phosphate crystals.
  • Calcium oxalate stones - These crystals form when there is a concentration of calcium in the urine.
  • Uric acid stones - Far less common than other types of bladder stones, these stones are primarily found in breeds whose livers have an inability to absorb uric acid.

Causes

Stones form due to a variety of causes which can include:

  • Chronic urinary tract infections - Some of the same bacteria that produce urinary tract infections also produce an enzyme called urease that permits the components of struvite crystals to bond together and form stones.
  • Diet and Urine pH - A dog's diet affects the pH of its urine. Alkaline urine has pH higher than 7.0, and this creates the right environment for struvite crystals to form. Acidic urine with a pH of less than 7.0 creates the right environment for calcium oxalate crystals to form.
  • Mineral concentration in the urine - The type of minerals present depends a lot on a dog's diet and metabolism, but their concentration in the urine depends largely on how much water a dog typically drinks. The lower the water intake, the more concentrated the urine becomes, and the more likely it is that crystals could form and become stones.
  • Genetic factors - Some breeds appear more apt to develop bladder stones. Toy dogs also appear more likely to develop stones than large dogs, although virtually any dog can develop bladder stones when conditions are right.

How Stones Are Diagnosed

Vets have several ways to diagnose a case of urinary tract stone disease (urolithiasis).

Symptoms

Owners typically become aware their dogs have a problem based on the physical symptoms their pets display.

Main symptoms include:

  • Frequent urination
  • Straining to urinate
  • Painful urination
  • Blood in the urine

Additional signs may include:

  • Irritability
  • Loss of appetite
  • Reduced activity
  • General weakness

Diagnostic Procedures

Although the appearance of symptoms may lead a vet to suspect stones, several procedures are used to confirm their presence.

  • Urinalysis - The vet will perform a urinalysis to identify which kind of crystals are present in order to determine the best way to treat the affected dog.
  • X-Rays - Some bladder stones are opaque and readily show up on an x-ray, but it's sometimes necessary to inject dye into the bladder to see stones that are not opaque enough to show up on the film.
  • Ultrasound - An ultrasound can also be useful when the stones aren't easily visible on an x-ray. In some ways, an ultrasound gives a clearer image of the stones and their position.

Treatment

Vets treat bladder stones in dogs in a variety of ways depending on their mineral makeup as well as their location and how much of a threat they pose to the dog. Here are some of the most common treatments used.

  • Diet and medication - In the case of struvite crystals, a change in diet can lower the urine pH and make it more acidic. This helps dissolve the stones as well as discourage new struvites from forming. If the dog also has a urinary tract infection, which is highly likely, the vet will also prescribe antibiotics.
  • Urohydropropulsion - This technique involves a procedure to fill the bladder with fluid, followed by an attempt to apply pressure on the bladder and force the stones out through the urethra. This technique can only be used on stones that are small enough to pass, and this is determined via an x-ray.
  • Catheterization - If a bladder stone enters a male dog's urethra, the vet will anesthetize the animal and use a catheter to push the stone back up into the bladder where it will likely need to be surgically removed. The immediate benefit of catheterization is that it allows the bladder to empty, and this decreases the pain and pressure the dog feels.
  • Surgical removal - This treatment is reserved for stones that cannot be treated or removed in any other way. Although it's usually quite effective, there are always risks associated with any type of surgery, including reactions to anesthesia and post operative infections.

Follow Up Is Necessary

Once a dog has experienced a case of bladder stones, the condition can recur. Even managing the dog's condition through diet doesn't guarantee that new stones won't form at some point in the future, especially if there is a genetic factor in play. The best thing you can do is have your dog checked periodically to see if new stones are forming. Your vet will advise you on how often to bring your dog in and make other recommendations to help you manage your pet's health.

Bladder Stones in Dogs