Nutritional Support for Dogs with Bladder Stones

My dog had bladder stones removed, and they were sent for analysis to determine their composition. Once we know their makeup, how can we prevent them from coming back?

Bladder stones (also called uroliths or urolithiasis) are common in dogs. They are the result of one or more underlying abnormalities, making stone analysis a critical step in the diagnostic process. It is also important to evaluate a dog’s food and water intake before the bladder stone diagnosis, and then analyze blood and urine for clues as to how nutrition may help reduce the risk of another bladder stone forming.

Bladder stones set the stage for infection in the urinary tract, and struvite stones grow more quickly if the dog already has a urinary tract infection. Consequently, urinary tract infection and bladder stones commonly occur together. Therefore, your veterinarian may recommend long-term antibiotics to kill bacteria on an ongoing basis while the bladder heals from surgery and the bladder lining returns to normal. Controlling or eliminating an infection in the bladder is one important way to prevent recurrence of bladder stones.

Is there any chance that bladder stones can be dissolved rather than resorting to surgery?

The opportunity to dissolve bladder stones in dogs, called dissolution, depends on the composition of the stones. Unfortunately, the most effective way to determine the composition of a canine bladder stone is to remove one and have it analyzed.

"The most effective way to determine the composition of a canine bladder stone is to remove one and have it analyzed."

That said, it may be possible to draw some conclusions about the composition of a bladder stone based on crystals identified during urinalysis. Also, it may be possible to retrieve a small bladder stone for analysis via a urethral catheter.

Your veterinarian can advise if medical dissolution is a reasonable option for your dog. In most cases, surgical removal of bladder stones is the treatment of choice. Surgery provides the following benefits:

• Prevents blockage of urine outflow, which is a true emergency.
• Relieves the dog of the discomfort of stones in the bladder.
• Allows bladder healing to begin.
• Allows for definitive analysis of the stone, which provides the best opportunity to prevent recurrence.

How will I know what to feed my dog to prevent his bladder stones from recurring?

The nutritional focus for a particular dog will depend on their specific diagnosis, and your veterinarian is a key partner in creating an overall plan that best fits your dog's bladder stone composition. There are, however, some general statements that can be made about the nutritional management of bladder stones that occur in dogs.

Struvite Stones

Dissolution of struvite stones may be possible by resolving an existing urinary tract infection and using an appropriate nutrient profile. Veterinary therapeutic diets marketed to dissolve struvite stones contain reduced magnesium and phosphorus, and are designed to lower the urine pH (below 6.5). Products include Hill’s Prescription Diet® c/d® or s/d®, Purina® Pro Plan® Veterinary UR Urinary™, Rayne Clinical Nutrition Adult Health-RSS™, and Royal Canin Urinary SO™. 

The complete prevention plan will depend on the individual dog, but dietary management generally focuses on increasing daily water intake and creating a slightly acidic urine in the bladder environment. An appropriate nutrient profile for dissolution will increase the dog’s thirst and create a more dilute urine (to reduce the chance of crystals forming into a stone). Some therapeutic diets may be higher in total fat content, creating a concern about pancreatitis, which means close monitoring is necessary. Using dietary therapy to dissolve struvite stones can take a few weeks or up to three months.

Oxalate Stones

Dissolution of calcium oxalate stones is not possible, so the nutritional focus is on preventing recurrence once the stone has been removed. The nutrient of greatest interest is water. Pet owners can help their dog increase water intake by offering wet food or soaking dry food in water before each meal. 

Veterinary therapeutic diets marketed to reduce the recurrence of calcium oxalate stones contain modified amounts of calcium to reduce the calcium excreted in urine. These products also attempt to lower oxalic acid in the urine. Human foods or table scraps may be a problem for dogs who’ve formed stones, so treats should be limited to the therapeutic diet recommended by the veterinarian to keep the dog’s risk of recurrence as low as possible.

Purine Stones

Dissolution of purine stones may be possible with protein-restricted therapeutic nutrition combined with additional measures (increasing water intake and urine production; creating an alkaline urine pH; eliminating any existing urinary tract infection; and giving a medication called allopurinol). This plan is the same as that used to reduce purine stone recurrence once the stones have been removed or dissolved.

Calcium Phosphate Stones

Dissolution of calcium phosphate stones has not proven to be effective. Prevention is complicated, because these stones are uncommon and may result from several underlying causes at once. Nutritional prevention of recurrence involves feeding wet versus dry food, limiting sodium intake, and managing urine pH (depending on the dog's metabolic profile). There are no specific diet recommendations. The dog may also need additional medication.

Cystine Stones

Dissolution of cystine stones may be possible using a protein-restricted therapeutic food with a controlled sodium level, and one that supports an alkaline urine pH (examples include Hill's Prescription Diet® u/d® or Royal Canin® UC Low Purine). Any existing urinary tract infection must be resolved. This nutrient profile would also be used following surgery. Your veterinarian may prescribe potassium citrate (brand names NutriVed, Urocit-K®) to alkalinize the urine. Tiopronin (brand name Thiola®) may be used to bind to excess cystine and remove it from the body.

Silica Stones

Silica stones are rare and dissolution has not been documented. Post-surgery, there is limited data to provide a clear path to prevention. General guidelines include feeding a nutrient profile with reduced vegetable protein and other plant-based ingredients, higher animal protein, feeding moist food versus dry, and feeding a food that supports an alkaline urine pH. A urine alkalinizing agent (such as potassium citrate) may also be needed.

Regardless of the ultimate treatment of canine bladder stones, whether surgical removal or dissolution, nutrition will play a role in preventing recurrence. Once a nutritional profile has been chosen, it is important to feed only what has been prescribed, so speak to your veterinarian before offering any additional food or treats. The add-ons may undermine the effectiveness of the prescribed nutrient profile at preventing the recurrence of bladder stones.