Bladder Stones

The signs of bladder stones closely overlap with other urinary conditions, which is why imaging is required to confirm them:

• Straining to urinate — frequent squatting or posturing with little urine produced
• Blood in the urine — pink, red, or brown discoloration
• Frequent, urgent urination in small amounts
• Urinating in unusual spots — on cool floors, outside the litter box, or in corners
• Crying or vocalizing when urinating
• Licking the genital area persistently
• In cases of urethral obstruction: complete absence of urine, straining without any output, progressive lethargy and vomiting — this is an emergency

Some pets — particularly those with chronic low-grade disease — show minimal signs until a stone grows large enough to cause a problem or shifts into the urethra. Routine urinalysis at annual wellness visits often catches crystals before stones form.

Bladder stones form when urine becomes supersaturated with certain minerals, which then crystallize and aggregate. The main stone types and their risk factors include:

• Struvite (magnesium ammonium phosphate) — most common in dogs; in dogs nearly always associated with bacterial UTI (the bacteria raise urine pH, promoting crystal formation); cats more often form struvite stones without infection
• Calcium oxalate — the most common stone type in cats and increasingly common in dogs; linked to dietary calcium and oxalate, metabolic predispositions, hypercalcemia, and certain breeds; does not respond to dietary dissolution
• Urate — seen in Dalmatians (a breed-specific metabolic abnormality), English Bulldogs, and dogs with liver shunts (portosystemic shunts)
• Cystine — uncommon; a genetic transport defect causes excess cystine in urine; Newfoundlands, Mastiffs, Dachshunds predisposed

Breed predispositions: Miniature Schnauzers, Shih Tzus, Yorkshire Terriers, and Bichon Frises form calcium oxalate stones at higher rates. Low water intake and infrequent urination increase the concentration of all crystal types.

Imaging is essential — urinalysis alone shows crystals but cannot confirm that formed stones are present, nor reveal their size or location. Our diagnostic approach:

• Abdominal radiographs (X-rays) — most struvite and calcium oxalate stones are dense enough to be visible on plain film; done in-house with digital radiography for fast results
• Abdominal ultrasound — detects stones that may not be radio-opaque (like some urate stones), evaluates the kidneys and bladder wall, and identifies stones in the urethra; also allows assessment of stone number and size
• Urinalysis and urine culture — identifies infection (strongly suggesting struvite in dogs), crystal type in the urine, and concurrent kidney involvement
• Blood panel — evaluates kidney function and calcium levels; elevated calcium can drive calcium oxalate formation
• Stone analysis — when stones are retrieved, laboratory analysis of their mineral composition is the definitive guide for prevention planning

Treatment depends critically on the stone type:

• Struvite dissolution diet — prescription diets (such as Hill's s/d or Royal Canin Urinary S/O) acidify urine and restrict the minerals that make up struvite; stones dissolve over 4–12 weeks in most dogs; requires follow-up radiographs every 4 weeks to confirm progress; concurrent antibiotics if infection is present
• Cystotomy (surgical removal) — required for calcium oxalate and other non-dissolvable stones, or for any stone causing an acute obstruction; all retrieved stones are submitted for analysis; Dr. Schulman performs this procedure with experienced anesthetic monitoring by our team
• Voiding urohydropulsion — a non-surgical technique using bladder flushing to expel small, smooth stones in appropriate patients
• Urethral catheterization — for emergency relief of an obstructed urethra, followed by surgical planning
• Long-term prevention — prescription prevention diet, increased water intake (wet food, water fountains), and regular urinalysis monitoring; urate stones in some dogs respond to the medication allopurinol plus a low-purine diet

Any pet straining to urinate, passing blood in the urine, or urinating in unusual places should be evaluated promptly — within the same day if straining with little to no output. A male cat or dog completely unable to urinate is an emergency: call us immediately. For pets with a history of bladder stones, regular recheck urinalysis and radiographs (every 6–12 months) are the best way to catch recurrence before stones reach a problematic size. Our Calabasas team provides in-house imaging and same-day stone-detection so you can often have a plan within a single appointment. Book an appointment today.