Bladder Stones in Cats: Understanding the Causes, Symptoms & Treatment

Bladder stones are formed from minerals and organic compounds that are normally found in urine. When a cat’s urine has high concentrations of magnesium, phosphorus, calcium, and protein, these substances can come together and form solid objects that resemble stones.

Bladder stones can be as small as a grain of sand all the way up to several inches in diameter. Some are smooth and some have a spikey surface.

Other terms for cat bladder stones

• Urolith
• Urocystolith
• Cystic urolith
• Cystic calculi
• Urinary stone

Are stones the same thing as bladder crystals?

Bladder crystals are tiny mineral structures that form in a cat’s urine. They are too small to be seen without a microscope. In some cases, it is normal for cats to have a few crystals in their urine.

When a cat has a lot of these crystals, they can clump together and form tiny bladder stones. Bladder stones may increase in size over time if they are not treated. 

Which cats have a higher risk?

Below is a table that shows risk factors for different types of cat uroliths. By far, the most common types of feline bladder stones are calcium oxalate and struvite stones. 

According to Cornell University veterinary specialists, other risk factors for cats to develop bladder stones include being spayed or neutered, being overweight and living strictly indoors. Male cats are much more likely to develop urethral obstructions from uroliths than females. (1)

How common is the condition?

Bladder stones are a common issue among cats. In 2017, Healthy Paws reported that urinary tract problems were the second most common insurance claim. (4) Studies show that up to 25% of cats with lower urinary tract diseases have bladder stones. (5) 

How does it affect my cat’s body?

Bladder stones can cause discomfort, pain, and potentially life-threatening complications in cats. They can irritate the bladder lining, cause urinary obstruction, increase the risk of infections, and damage the bladder wall.

It’s not fully understood what causes bladder stones in cats. It’s believed that a high mineral concentration in cat urine may increase the risk of forming stones. However, normal cat urine can have a high mineral concentration without ever developing bladder stones.

Other conditions that cause the formation of bladder stones

• Eating diets high in magnesium, phosphorus, calcium, chloride and fiber
• Bladder infection (struvite)
• Increased urine pH (struvite)
• High blood calcium levels (calcium oxalate)
• Liver circulation abnormalities (urate)
• Kidney abnormalities (cystine)

What are the symptoms?

Some bladder stones don’t cause any symptoms at all. When they do cause symptoms, they’re very similar to those seen with other lower urinary tract diseases, including Feline Idiopathic Cystitis (FIC). 

Symptoms of cat bladder stones include

• Urinating outside the litterbox
• Vocalizing while urinating
• Straining to urinate
• Frequent urination
• Bloody urine
• Foul urine odor
• Inability to pass urine, vomiting and lethargy (with an obstruction)

Testing is required to diagnose a cat with bladder stones since the symptoms are the same as those seen with other bladder problems.

Is the condition contagious?

Cat bladder stones are not contagious to other cats, humans or other animals. 

Diagnosing a cat with bladder stones typically requires testing, although in some cases, a tiny stone may be passed or larger stones may be felt during a physical exam by a veterinarian.

Abdominal radiographs are effective at detecting bladder stones larger than 3 mm, but they can’t identify the type of stone. Abdominal ultrasound imaging is useful for showing stones and assessing the bladder’s soft tissue.

Urinalysis is an essential test that checks for blood, crystals, and abnormal pH levels. A urine culture can identify bacterial infections and help guide the selection of antibiotics.

Your veterinarian may order an analysis of bladder stones passed by the cat or retrieved surgically. Identifying the type of stone can help prevent future occurrences.

Basic blood chemistry and cell count tests are performed to rule out underlying liver, kidney, or endocrine diseases.

Non-Surgical Treatment

The treatment of feline bladder stones depends on their size and type. 

Small struvite stones can be dissolved over a few weeks with special food that changes the pH of the urine. 

For non-struvite stones that are smaller than 5 mm, non-surgical voiding hydro propulsion can be performed using sterile saline to flush the stones out of the bladder. Laser lithotripsy and cystoscopic removal of cat uroliths are non-surgical treatments offered by some veterinary specialists.

In the non-surgical emergency treatment of urethral obstruction, a urethral catheter is typically used to push the lodged stone back into the bladder. Some cats may require surgery later to remove the stone from the bladder. 

Surgical Treatment

To treat larger bladder stones in cats, the most common method is through a surgery called a cystotomy. This procedure involves a veterinary surgically opening the cat’s abdomen and bladder to remove the stones. 

After the procedure, cats are often hospitalized for a day or two to make sure they can urinate normally before going home. Most cats recover completely from the surgery within a couple of weeks. 

Special Therapeutic Diets

Special diets for urinary health can dissolve some bladder stones and prevent the recurrence of others.

• Struvite bladder stones can be dissolved by feeding a prescription diet over a period of weeks to months. The food changes the pH of the cat’s urine to be more acidic, causing the struvite stones to break apart and pass in the urine.
• Calcium oxalate stones cannot be dissolved by a special diet, but prescription cat foods can help prevent their recurrence.
• Cats with urate bladder stones may benefit from eating wet-form prescription kidney diets.

Tufts University Veterinary School’s clinical nutrition service has a good article on dietary treatment of feline uroliths.

Medications

Medications depend on the type of stone your cat has or is suspected of having. Underlying conditions and pain assessment also influence prescription choice. A few of the more common meds prescribed are listed below.

Prognosis

Prevention

If your cat has been treated for bladder stones, you can take steps to prevent them from recurring. Follow your vet’s recommendations for specific dietary changes, medications and lifestyle changes. 

Simple strategies for preventing bladder stones in cats include feeding high-quality food and preventing obesity. Increase your cat’s water intake by feeding them moist food and providing fresh flowing water. 

By following your vet’s recommendations and making some simple changes, you can help keep your cat healthy and prevent future episodes of bladder stones.

When should my cat see a veterinarian?

If you notice changes in your cat’s urination habits, it’s important to consult your veterinarian as soon as possible. Early treatment of bladder issues can help your cat recover quickly. Ignoring the problem could lead to serious complications such as kidney failure or urethral obstruction.

What questions should I ask the veterinarian?

• What kind of stone does my cat have?
• Does my cat have an infection?
• Does my cat need surgery?
• Should my cat take pain medicine?
• Should my cat eat prescription food?
• When should I bring my cat in for a recheck exam?