Cat bladder stones (uroliths) are mineral deposits that form inside the bladder and can cause pain, urinary blockages, and serious health complications. Unlike the more commonly discussed urinary crystals, stones are large enough to cause significant physical obstruction and typically require medical or surgical intervention. Understanding the types, signs, and treatment options helps cat owners act quickly when symptoms appear.
What Are Bladder Stones in Cats?
Bladder stones are solid concretions of minerals that accumulate in the urinary bladder. They form when minerals in the urine become supersaturated and begin to crystallize, gradually building up into stones over weeks to months. Stones vary widely in size — from tiny gravel-like particles to stones several centimeters in diameter.
The two most common types in cats are struvite and calcium oxalate, each with different causes, treatment approaches, and risk profiles. Less commonly, cats develop urate, cystine, or silica stones.
Bladder stones should not be confused with urinary crystals, which are microscopic and detected on urinalysis. Crystals can precede stone formation but don’t always become stones. Stones, once formed, cannot dissolve on their own and cause more dramatic clinical symptoms.
Types of Bladder Stones in Cats
Struvite stones are composed of magnesium ammonium phosphate and are the most common type in cats. They form in alkaline urine and are frequently associated with urinary tract infections (UTIs). Unlike in dogs, where most struvite stones are infection-related, some cats form struvite stones without infection — particularly in cats fed high-magnesium or high-ash diets. The good news: struvite stones can often be dissolved with a prescription dissolution diet over 4–12 weeks, making them the most medically manageable type.
Calcium oxalate stones form in acidic urine and are more common in older, neutered male cats, particularly in certain breeds like Persians, Himalayans, and Burmese. These stones cannot be dissolved with diet and require surgical or non-surgical removal. Once removed, recurrence rates are high — up to 50% within three years — making long-term dietary management essential.
Urate stones are uncommon in cats and typically associated with liver disease or portosystemic shunts, which allow blood to bypass liver processing. Treatment focuses on both stone removal and addressing the underlying liver condition.
Signs and Symptoms
Bladder stones cause inflammation and irritation of the bladder lining (cystitis), leading to a recognizable set of urinary symptoms. In male cats, even small stones can cause life-threatening urethral blockages.
Common symptoms include:
- Straining to urinate: Cats may spend extended time in the litter box with little or no urine produced.
- Frequent, small urinations: Bladder inflammation reduces capacity and increases urgency.
- Blood in urine (hematuria): Urine may appear pink, red, or brown.
- Crying or vocalizing while urinating: Indicates pain during urination.
- Urinating outside the litter box: Cats associate the litter box with pain and seek alternative locations.
- Grooming the genital area excessively: Response to discomfort in the urinary tract.
- Lethargy, vomiting, or loss of appetite: More severe signs suggesting complete obstruction — a veterinary emergency.
A male cat that has not urinated in 24 hours or is vocalizing while straining requires emergency veterinary care. A blocked urethra can cause kidney failure and death within 24–48 hours.
Diagnosis
Veterinarians diagnose bladder stones through a combination of physical examination, urinalysis, and imaging. Abdominal X-rays (radiographs) detect most stones because they are radiopaque — visible on X-ray. Calcium oxalate and struvite stones typically show well on X-ray, though some stones (like cystine or urate) are radiolucent and require ultrasound for detection.
Urinalysis identifies crystals, blood cells, bacteria, and pH — information that helps predict stone type. Urine culture confirms or rules out bacterial infection. Blood panels assess kidney function, which may be compromised if there is chronic urinary obstruction.
Stone type is confirmed definitively only after removal and laboratory analysis (quantitative mineral analysis). This is important because treatment differs substantially between types.
Treatment Options
Dietary dissolution is the least invasive option and works only for struvite stones. Prescription diets (such as Hill’s c/d or Royal Canin Urinary S/O) lower urine pH and magnesium content, creating conditions where struvite stones dissolve. This process typically takes 4–12 weeks, with X-rays every 4 weeks to monitor progress. The cat must eat exclusively the dissolution diet — no treats or other foods.
Surgical cystotomy is the definitive treatment for calcium oxalate stones and for struvite stones that are too large to dissolve quickly or causing acute obstruction. The surgeon opens the bladder under general anesthesia and manually removes all stones. Recovery is typically 10–14 days. Stones removed surgically should be submitted for analysis to guide prevention.
Urohydropropulsion is a non-surgical technique where the bladder is flushed under sedation to push small stones out through the urethra. This works only for very small stones and is more commonly used in male cats after catheterization or in females with wider urethras. It does not work for large or multiple stones.
Lithotripsy uses shock waves to break stones into smaller fragments that can pass or be flushed out. This technique is available at veterinary specialist centers and works best for certain stone types and sizes.
Preventing recurrence is a long-term commitment. For calcium oxalate prevention, increasing water intake through wet food and water fountains, feeding a controlled-mineral prescription diet, and monitoring urine pH every 3–6 months significantly reduces recurrence risk.