Bladder Stones

Bladder Stones in Cats.


Bladder stones are an uncommon cause of cystitis in cats. Unlike dogs, bladder stones in cats are usually not associated with an infection.


Discussing cystitis in cats is confusing. This is because words are used differently by different people. This is a list of our use of the words. Beware that other sources may use other definitions.

Bladder Stone: A concretion of minerals and other materials that forms within the bladder.Crystaluria: Crystals in the urine. 

Cystitis: Inflammation of the urinary bladder regardless of cause. Less than 10% of cats with cystitis have a bladder stone.

Dysuria: Difficult or painful urination. This may manifest as squatting to urinate for long periods, making frequent trips to the litter box, urinating outside of the litter box, howling, or a number of other ways.

HematuriaBlood in the urine. Sometimes the urine still looks yellow and the blood can only be detected microscopically or with chemical tests. Sometimes it looks like pure blood.

House soiling: Urinating or defecating in the house, outside of the litter box. Some veterinarians use the term periuria or inappropriate urination.

Stranguria: Straining to urinate. Since cats don't usually make a face or an odd noise when they strain, a lot of times humans don't recognize what they are doing to be straining.

Stress: Psychological stress. This is an internal reaction to usually external stimuli. Anything that causes a cat to become upset, including medicating them, can cause stress.

Urethral Spasm: Inappropriate and painful contraction of the muscle of the bladder / urethral sphincter. Urethral spasms can prevent a cat from being able to urinate or they may cause an unsteady or intermittent stream of urine.

Urinary Obstruction: Anything that obstructs a cat's urethra so that they can't urinate. This is sometimes a "plug" of debris (crystals, blood, etc.) and it is sometimes a urethral spasm. Urinary obstructions are life threatening.  

UTI: Urinary Tract Infection. Infection anywhere in the urinary tract including kidneys, ureters, bladder, or urethra. If it is in the bladder, it usually causes bladder inflammation (bacterial cystitis). 

Causes of Bladder Stones in Cats.

Diets high in certain minerals and low in water (dry food) can predispose a cat to bladder stones. The pH of the urine can be a factor. A lot of times we don't really know why one cat gets a stone, and another doesn't.

Ash in the Diet

"Ash" is the component of food that is left over when the food is burned (i.e., it is the same as ashes).  It is composed of minerals, such as phosphorus and calcium. We used to try to limit ash in the diet because it may be associated with crystals. Ash is a normal part of food and considering its percentage in a given food is usually not helpful.

Signs of Bladder Stones

The signs of bladder stones are the same as the the signs of bladder infection and idiopathic cystitis. 


Cats show pain in a number of ways including hiding, not eating, and vocalizing. Frequently the signs of pain are subtle and humans don't know that their cat is in pain.

Frequent Urination:

With cystitis from bladder stones, the nerve endings in the bladder are stimulated, making it feel to the cat as though they have to urinate, even when the bladder is empty of urine. Humans will see the cat squatting as though to urinate with nothing coming out. This is problematic in that the exact same thing is seen when a cat has a urinary obstruction. They squat to urinate and no urine comes out.

House Soiling:

For reasons that are variable and not fully understood, some cats will urinate outside the litter box when they have a bladder stone.

Complications of Bladder Stones

Urinary Obstruction:

Urinary obstruction can occur directly from a bladder stone independent of any cystitis.

If your cat is squatting to urinate and no urine is coming out, you should consider it a life-threatening emergency. It cannot wait until morning.

Pain and Discomfort:

Cats with cystitis from stones are in pain, even though it may not be obvious to people.

It is important to realize that if your cat is going in and out of the litter box, trying to urinate frequently with little success, they are in pain.

Treatments for Bladder Stones

Dietary modification. Some stones can be "dissolved" with dietary therapy.  Unlike dogs, cats rarely have infection associated with the stones so antibiotics aren't usually used.

Hydropropulsion. If the stones are small enough, they can sometimes be forced out of the bladder while the cat is under anesthesia by a technique called voiding urohydroprpulsion. If unsuccessful, with the cat still under anesthesia, we go straight to surgery.

Surgery. Some stones can only be resolved with removal.

Preventing Bladder Stones

Bladder stones will often recur if nothing is done to prevent it. The treatment to prevent recurrence will depend on the type of stone and other underlying conditions. A lot of times putting the cat on a canned diet and adding water at each meal is all that is needed.

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