Bladder Stones in Dogs: Types, Symptoms & Treatment

Last reviewed April 2026 · Veterinary reference article

What Are Bladder Stones?

Bladder stones (uroliths) are crystallized mineral deposits that form inside the urinary bladder. They develop when certain minerals in the urine become so concentrated that they precipitate out of solution and aggregate into solid masses. Stones vary enormously — from microscopic grit that passes in the urine to single large stones that fill the bladder and weigh several hundred grams.

Stone type matters enormously for treatment. Two dogs with identical symptoms — blood in the urine, straining, recurrent UTIs — may need completely different treatment plans depending on whether their stones are struvite or calcium oxalate. This is why stone analysis after removal is essential, not optional.

The Five Main Stone Types

Each stone type has a distinct cause, affected population, and treatment approach. Knowing the type is the cornerstone of management.

Struvite Stones: The Infection-Driven Type

Struvite is the most common bladder stone in dogs, and the important distinction from cats is that canine struvite stones are almost always infection-induced. Urease-producing bacteria (most often Staphylococcus pseudintermedius or Proteus mirabilis) break down urea in the urine into ammonia, raising urine pH and creating conditions where struvite crystals precipitate.

Because the underlying driver is infection, treatment must address both the stone and the bacteria. A prescription dissolution diet (very low in magnesium, phosphorus, and protein) acidifies the urine and reduces mineral availability; antibiotics selected via urine culture eliminate the bacteria. Stones dissolve over 4–12 weeks with monthly X-ray monitoring. Recurrence is prevented by resolving all future UTIs promptly.

Calcium Oxalate Stones: Surgery Is Required

Calcium oxalate stones do not dissolve with any dietary or medical protocol — once present, they must be physically removed. They form when urine calcium or oxalate levels are elevated, or when urine is persistently acidic. Risk factors include hypercalcemia (elevated blood calcium from hyperparathyroidism, Addison's disease, or malignancy), certain medications (furosemide, corticosteroids), and genetic factors in predisposed breeds.

Small stones (under ~5mm) in the bladder may be removed via urohydropropulsion — a non-surgical technique where the bladder is filled with saline and the dog is tilted while the vet manually expresses the bladder to flush small stones through the urethra. Larger stones, multiple stones, or stones in male dogs (narrower urethra) typically require surgical cystotomy — opening the bladder under general anesthesia. After removal, ongoing prevention focuses on increasing water intake to dilute urine and feeding a lower-calcium, lower-oxalate diet.

Urate Stones: Genetics and Liver Shunts

Urate stones form from uric acid, a purine breakdown product. In most dogs, uric acid is converted to allantoin in the liver and excreted safely. Dalmatians carry a genetic mutation that bypasses this conversion, leading to high uric acid in urine throughout their lives — making them heavily predisposed to urate stones regardless of diet. In other breeds, urate stones raise suspicion for a portosystemic (liver) shunt, which diverts blood around the liver and impairs uric acid processing. Any non-Dalmatian dog with urate stones should be screened for a liver shunt with bile acids testing or abdominal imaging. Urate stones are radiolucent (invisible on standard X-rays) — ultrasound is required for detection.

Symptoms of Bladder Stones in Dogs

Symptoms are caused by the physical irritation of stones against the bladder wall, secondary infection, and, in severe cases, obstruction of urine flow. Classic signs include:

• Dysuria — straining, squatting repeatedly, crying during urination
• Hematuria — blood in the urine, ranging from pink tinge to frank red blood
• Pollakiuria — abnormally frequent urination in small amounts
• Inappropriate urination — accidents indoors, urinating in unusual spots
• Genital licking — persistent licking at the penis or vulva
• Recurrent UTIs — stones create a surface for bacterial colonization; UTIs keep recurring despite antibiotic treatment until stones are removed
• Reduced urine stream or dribbling — suggests partial obstruction

Some dogs — particularly those with smooth, large stones that fill the bladder without moving into the urethra — are entirely asymptomatic. These are often discovered during routine imaging or workup for an unrelated problem.

Diagnosis

Urinalysis and Urine Culture

The first step is a urinalysis, ideally from a cystocentesis sample (collected directly from the bladder via a needle — avoids contamination from the urethra and skin). Key findings:

• Crystals under microscopy — suggests stone mineral type (but does not confirm stone composition)
• RBCs (red blood cells) — indicates bladder wall irritation
• WBCs (white blood cells) and bacteria — indicates concurrent UTI
• Urine pH — alkaline favors struvite; acidic favors calcium oxalate and urate
• Urine specific gravity — dilute urine reduces stone risk; concentrated urine increases it

Urine culture with antibiotic sensitivity testing is essential for guiding antibiotic selection in struvite cases and for any dog with suspected secondary UTI.

Imaging

Abdominal X-rays (radiographs) detect radiopaque stones — struvite, calcium oxalate, and cystine are all visible on X-ray. X-ray also shows stone number, size, and location, and can identify stones in the kidneys or ureters in addition to the bladder.

Abdominal ultrasound detects radiolucent stones (urate, some cystine) invisible on X-ray, and provides better detail on small stones and mucosal thickening. Some vets use both X-ray and ultrasound together for a complete picture.

Stone Analysis

After stones are removed surgically, passed spontaneously, or retrieved via urohydropropulsion, they should be submitted to a veterinary laboratory for mineral analysis. This is the only way to definitively confirm stone type — urine crystal type may suggest composition but is not reliably accurate. Stone analysis results directly determine prevention strategy.

Treatment by Stone Type

Struvite: Medical Dissolution

Struvite dissolution is one of veterinary medicine's success stories — genuine non-surgical resolution of stones with diet and antibiotics alone:

1. Confirm the stone type via urinalysis/imaging (wait for culture results)
2. Begin culture-guided antibiotic therapy — continued for the full duration of dissolution plus 2 weeks beyond
3. Start a prescription dissolution diet exclusively — no treats, table scraps, or other food during dissolution; these raise urine pH and slow dissolution
4. Recheck urinalysis monthly — urine should become sterile and acidic within 2–4 weeks
5. Recheck abdominal X-rays monthly — stones typically dissolve within 4–12 weeks; treatment continues until stones are no longer visible on imaging

Common dissolution diets: Hill's Prescription Diet s/d (short-term dissolution), Royal Canin Veterinary Diet Urinary SO. These are not appropriate for long-term feeding — after dissolution, switch to a maintenance urinary diet.

Calcium Oxalate: Surgical Cystotomy

Cystotomy (surgical opening of the bladder) is the definitive treatment for calcium oxalate stones. The procedure is performed under general anesthesia: the bladder is opened, stones are removed and submitted for analysis, and the bladder wall is flushed to remove any remaining grit. Recovery is typically 10–14 days. Complication rates are low in experienced hands.

For small calcium oxalate stones (<5mm) in female dogs or larger female dogs where the urethra accommodates flushing, urohydropropulsion can avoid surgery. The vet fills the bladder, positions the dog vertically, and uses abdominal pressure to expel small stones through the urethra. It requires sedation but not general anesthesia. Not appropriate for male dogs due to the narrower urethra.

Prevention after removal focuses on diluting urine: encourage water intake through wet food, water fountains, and adding water to dry food. A prescription urinary maintenance diet (Royal Canin Urinary SO, Hill's u/d) helps moderate calcium and oxalate. Avoid high-oxalate foods (spinach, beets, nuts). Recheck X-rays every 3–6 months — recurrence rates are high (up to 50% within 2–3 years without prevention).

Preventing Recurrence

Bladder stones recur — this is the rule, not the exception. The single most impactful prevention strategy across all stone types is increasing water intake to produce dilute urine (target urine specific gravity below 1.020). Practical ways to achieve this:

• Feed wet/canned food instead of or in addition to dry kibble
• Add warm water or low-sodium broth to dry food
• Use a circulating water fountain — dogs often drink more from moving water
• Place multiple water bowls in different locations around the home
• Feed a prescription urinary maintenance diet appropriate for the stone type
• Treat UTIs promptly and completely (culture-guided, not empirical) — recurrent UTIs drive struvite recurrence
• Schedule regular urinalyses (every 3–6 months) to catch recurrence before stones become large

Frequently Asked Questions