Bladder Stones in Dogs: Types, Symptoms and Treatment Options

Bladder stones (uroliths or calculi) are rock-like mineral deposits that form in the urinary bladder. They develop when dissolved minerals in urine become supersaturated — meaning there are more minerals than the urine can keep dissolved — and begin to crystallise. Over time, these microscopic crystals aggregate into stones that can range from sand-grain sized to several centimetres in diameter.

"Bladder stones are not all the same — and treating them as if they are is one of the biggest mistakes I see. A struvite stone and a calcium oxalate stone look identical on an X-ray, but they form for completely different reasons, respond to different diets, and may need different surgical approaches. Knowing the stone type changes everything about how we manage the case." — Dr. Sarah Chen, DVM

Several factors influence stone formation:

• Urine pH — some minerals crystallise in alkaline urine (struvite), while others form in acidic urine (calcium oxalate). Diet significantly influences urine pH
• Mineral concentration — diets high in certain minerals, combined with concentrated urine from inadequate water intake, create ideal conditions for crystal formation
• Urinary tract infection — certain bacteria (especially Staphylococcus and Proteus) produce urease, an enzyme that makes urine alkaline and promotes struvite stone formation. UTIs and stones often occur together — for more information, see our guide to UTIs in dogs
• Genetic predisposition — breed-specific metabolic traits make certain dogs prone to particular stone types
• Reduced water intake — concentrated urine is the enemy; dilute urine makes it harder for minerals to reach the saturation point needed for crystal formation

Dogs can have a single large stone, multiple small stones, or a combination. Some dogs develop bladder sand (very fine crystalline material) rather than discrete stones. The location matters too — while most stones form in the bladder, they can also develop in the kidneys, ureters, or urethra.

Identifying the stone type is crucial because it determines treatment. The two most common types account for approximately 85% of all canine bladder stones.

Struvite Stones (Magnesium Ammonium Phosphate)

Struvite stones make up roughly 40–45% of canine bladder stones. In dogs (unlike cats), they are almost always infection-induced — urease-producing bacteria create an alkaline environment where struvite crystals form rapidly around a nidus of bacteria and inflammatory debris.

• Predisposed breeds: Miniature Schnauzers, Bichon Frises, Cocker Spaniels, Shih Tzus
• Sex predilection: more common in females (who are more prone to UTIs)
• Key feature: they can often be dissolved with a combination of antibiotics (to clear the underlying infection) and a prescription dissolution diet

Calcium Oxalate Stones

Calcium oxalate stones account for approximately 40–45% of canine bladder stones and have been increasing in prevalence over recent decades. Unlike struvite stones, they are not associated with infection and form in acidic to neutral urine.

• Predisposed breeds: Miniature Schnauzers, Lhasa Apsos, Yorkshire Terriers, Bichon Frises, Miniature Poodles
• Sex predilection: more common in males
• Key feature: cannot be dissolved — they must be physically removed. They also have a high recurrence rate (approximately 30–50% within 2 years)

Less Common Stone Types

• Urate stones — associated with liver disease (portosystemic shunts) and specific breeds, particularly Dalmatians and English Bulldogs, who have a genetic defect in uric acid metabolism
• Cystine stones — caused by a genetic defect in amino acid reabsorption; seen most often in male Newfoundlands, English Bulldogs, and Dachshunds
• Silica stones — linked to diets high in plant-based ingredients; more common in German Shepherds, Golden Retrievers, and Labrador Retrievers

Stone analysis after removal is essential. Your vet will send any stones or fragments to a laboratory for mineral composition analysis, which guides the prevention plan.

Bladder stone symptoms often overlap with those of a urinary tract infection, which makes sense given that the two conditions frequently coexist. Some dogs with small stones may show no symptoms at all — the stones are discovered incidentally during imaging for another reason.

Symptoms to Watch For

• Blood in the urine (haematuria) — stones irritate and abrade the bladder lining, causing bleeding. Urine may appear pink, red, or brown. See our guide on blood in dog urine for a complete overview of possible causes
• Frequent urination — stones irritate the bladder wall, creating a persistent sensation of needing to urinate even when the bladder is nearly empty
• Straining to urinate — particularly concerning if your dog produces only dribbles or appears to be in pain
• Recurrent UTIs — if your dog has been treated for multiple UTIs that keep returning, bladder stones may be the underlying cause, providing a surface for bacteria to adhere to and evade antibiotics
• Urinary accidents — a previously house-trained dog may begin having indoor accidents due to urgency and irritation
• Inability to urinate — a stone lodged in the urethra can cause a complete blockage. This is a medical emergency requiring immediate veterinary attention

Diagnostic Approach

Your vet will typically use a combination of:

• Urinalysis — checks for crystals, blood, bacteria, and urine pH, all of which provide clues about stone type
• Urine culture — identifies any concurrent bacterial infection, which is essential for treating struvite stones
• Abdominal X-rays — most bladder stones are radioopaque (visible on X-ray). Multiple small stones often appear as a cluster of white densities within the bladder silhouette
• Abdominal ultrasound — detects stones that may not be visible on X-ray and provides additional information about bladder wall changes, kidney involvement, and stone size

Your vet may also recommend blood work to check kidney function and screen for conditions like diabetes or Cushing's disease that can contribute to stone formation.

Treatment for bladder stones depends on the stone type, size, number, and whether the dog is showing symptoms or has a urethral obstruction.

Medical Dissolution (Struvite Stones)

Because struvite stones in dogs are infection-induced, treatment targets both the stones and the bacteria:

• Antibiotics — culture-based antibiotic therapy must continue for the entire dissolution period (often 8–12 weeks) and for at least 2 weeks after the stones are no longer visible on X-ray
• Prescription dissolution diet — these diets are restricted in magnesium, phosphorus, and protein, and produce acidic urine that dissolves struvite. Popular options include Royal Canin Urinary S/O and Hill's c/d Multicare
• Monitoring — X-rays are taken every 4–6 weeks to track stone size. If stones are not shrinking, they may be a different composition than expected and require surgical removal

Surgical Removal (Cystotomy)

Surgery is the treatment of choice for calcium oxalate, urate, cystine, and silica stones, as well as struvite stones that do not respond to dissolution therapy. The procedure involves:

• General anaesthesia and an incision into the abdomen and bladder wall
• Removal of all visible stones, followed by thorough flushing of the bladder to retrieve any fragments or sand
• Post-operative X-ray to confirm no stones remain — even small fragments can serve as a nidus for new stone growth
• Recovery typically takes 10–14 days, with exercise restriction and a protective collar to prevent incision licking

Less Invasive Alternatives

• Voiding urohydropropulsion — small stones (under 5 mm) can sometimes be flushed from the bladder under anaesthesia by filling the bladder with saline and applying gentle pressure. This avoids surgical incision but only works for small, smooth stones
• Laser lithotripsy — available at veterinary referral centres, this technique uses a laser fibre inserted via cystoscope to fragment stones, which are then flushed out. It is minimally invasive but not suitable for all stone types or sizes

All removed stones should be submitted for laboratory analysis to confirm their mineral composition and guide the long-term prevention plan.

Prevention is just as important as treatment, because bladder stones have a significant recurrence rate. Calcium oxalate stones recur in 30–50% of dogs within 2 years without preventive measures, while struvite stones will return if the underlying infection is not fully resolved.

Dietary Management

Diet is the cornerstone of stone prevention, and the approach differs by stone type:

• Struvite prevention: a diet that maintains mildly acidic urine and limits magnesium and phosphorus. Preventing UTIs is equally important — address any anatomical or hormonal factors that predispose to infection
• Calcium oxalate prevention: a diet that avoids excessive acidification, maintains moderate calcium levels, and is not excessively restricted in protein. Contrary to intuition, very low-calcium diets can actually increase calcium oxalate risk by promoting calcium absorption from the gut
• Urate prevention: a low-purine diet (avoiding organ meats, certain fish, and legumes) combined with allopurinol medication in many cases

Understanding food labels is important when managing urinary health — our guide to reading pet food labels can help you make informed dietary choices for your dog.

Hydration Is Key

Regardless of stone type, keeping urine dilute is one of the most effective prevention strategies. Dilute urine means minerals are less likely to reach saturation and crystallise. Strategies to increase water intake include:

• Adding water or low-sodium broth to meals
• Feeding wet food instead of or alongside dry kibble
• Providing multiple water bowls in different locations
• Using a pet water fountain

Monitoring Schedule

Dogs with a history of bladder stones should have regular monitoring to catch recurrence early, before stones become large enough to cause symptoms:

• Urinalysis — every 3–6 months to check for crystals, pH changes, and infection
• Urine culture — every 3–6 months for dogs with a history of struvite stones
• Abdominal imaging — X-rays or ultrasound every 6–12 months, or sooner if urinary symptoms recur

Early detection of recurrence allows for intervention when stones are small — potentially treatable with dietary adjustment alone rather than requiring repeat surgery. Consistent follow-up with your vet and adherence to the recommended diet are the best insurance against bladder stone recurrence.